Slotted antenna device

Abstract

Slotted antenna device, comprising: a first electrically conductive component (110) with a first electrically conductive surface (110b) on a front side and a second electrically conductive surface (110a) on a back side and with at least one slot (112) extending from the first electrically conductive surface (110b) to the second electrically conductive surface (110a); a second electrically conductive component (120) on the back side of the first electrically conductive component (110), wherein the second electrically conductive component (120) has a third electrically conductive surface (120a) on the front side, the third electrically conductive surface (120a) being opposite to the second electrically conductive surface (110a); a rib-shaped waveguide element (122) on the second electrically conductive surface (110a) of the first electrically conductive element (110), wherein the waveguide element (122) has an electrically conductive waveguide surface (122a) that is opposite to the third electrically conductive surface (120a) and extends along the third electrically conductive surface (120a); and an artificial magnetic conductor on at least either the second electrically conductive surface (110a) or the third electrically conductive surface (120a), wherein the artificial magnetic conductor extends on both sides of the waveguide element (122), wherein the third electrically conductive surface (120a), the waveguide surface (122a) and the artificial magnetic conductor define a waveguide in an intermediate space extending between the third electrically conductive surface (120a) and the waveguide surface (122a); the waveguide element (122) has a first rib (122A) and a second rib (122B); one end of the first rib (122A) and one end of the second rib (122B) are opposite each other; viewed from a direction perpendicular to the waveguide surface (122a), at least one slot (112) is arranged between one end of the first rib (122A) and one end of the second rib (122B); which has at least one slot (112) through the first electrically conductive surface (110b) open to an external space and at least either a distance between the third electrically conductive surface (120a) and the waveguide surface (122a) or a width of the waveguide surface (122a) varies along a direction in which the waveguide element (122) extends.

Description

TECHNICAL AREA

[0001] The present disclosure relates to a slotted antenna device. STATE OF THE ART

[0002] An antenna device, in which one or more beam elements (hereinafter also referred to as "antenna elements") are arranged in an array on a line or plane, is used in various applications, e.g., in radar and communication systems. To radiate electromagnetic waves from an antenna device, it is necessary to supply each antenna element with electromagnetic waves (e.g., high-frequency signal waves) from a circuit that generates electromagnetic waves ("feed"). Such feed with electromagnetic waves is achieved via a waveguide. A waveguide is also used to transmit electromagnetic waves received at the antenna elements to a receiving circuit.

[0003] Traditionally, array antennas are fed using one or more microstrip lines. However, when the frequency of an electromagnetic wave to be transmitted or received by an array antenna is a high frequency above 30 gigahertz (GHz), as in the millimeter band, a microstrip line is subject to high dielectric loss, thus reducing the antenna's efficiency. Therefore, in such high-frequency regions, an alternative waveguide is needed to replace a microstrip line.

[0004] As alternative waveguide structures to the microstrip line, patent documents 1 to 3 and non-patent documents 1 and 2 disclose structures that guide electromagnetic waves using an artificial magnetic conductor (AMC) extending on both sides of a rib-type waveguide. Patent document 1 and non-patent document 1 disclose slot array antennas that utilize such a waveguide structure. LIST OF CITED PRINTED PUBLICATIONS Patent Literature [PTL 1] Specification of US Patent No. US 8 779 995 B2 [PTL 2] Specification of US Patent No. US 8 803 638 B2 [PTL 3] Specification of the European patent application, publication no. EP 1331688A1 [Non-patent literature] [NPL 1] Kirino et al., "A 76 GHz Multi-Layered Phased Array Antenna using a Non-Metal Contact Metamaterial Waveguide," IEEE Transaction on Antennas and Propagation, Vol. 60, No. 2, February 2012, pp. 840-853 [NPL 2] Kildal et al., “Local Metamaterial-Based Waveguides in Gaps Between Parallel Metal Plates,” IEEE Antennas and Wireless Propagation Letters, Vol. 8, 2009, pp. 84-87 SUMMARY OF THE INVENTION Technical Task

[0005] The present disclosure provides an antenna device based on a principle that differs from the conventional one. Solution to the task

[0006] A slot antenna device according to an implementation of the present disclosure is a slot antenna device comprising: a first electrically conductive component with a first electrically conductive surface on a front side and a second electrically conductive surface on a rear side, and with at least one slot extending from the first electrically conductive surface to the second electrically conductive surface; a second electrically conductive component on the rear side of the first electrically conductive component, wherein the second electrically conductive component has a third electrically conductive surface on the front side, the third electrically conductive surface being opposite to the second electrically conductive surface; a rib-shaped waveguide component on the second electrically conductive surface of the first electrically conductive component.wherein the waveguide element has an electrically conductive waveguide surface that is opposite to and extends along the third electrically conductive surface; and an artificial magnetic conductor on at least either the second electrically conductive surface or the third electrically conductive surface, the artificial magnetic conductor extending on both sides of the waveguide element. The third electrically conductive surface, the waveguide surface, and the artificial magnetic conductor define a waveguide in a space extending between the third electrically conductive surface and the waveguide surface. The waveguide element has a first rib and a second rib. One end of the first rib and one end of the second rib are opposite to each other. Viewed from a direction perpendicular to the waveguide surface,At least one slot is arranged between one end of the first rib and one end of the second rib. This slot is open through the first electrically conductive surface to an external space. At least one spacing between the waveguide surface and the third electrically conductive surface, or the width of the waveguide surface, is varied along a direction in which the waveguide element extends. ADVANTAGEOUS EFFECTS OF THE INVENTION

[0007] According to one embodiment of the present disclosure, a low-loss antenna device can be realized based on a principle that differs from the conventional one. BRIEF DESCRIPTION OF THE DRAWINGS [ Fig. 1] Fig. Figure 1 is a perspective view that schematically shows a non-restrictive example of the basic construction of a waveguide device. [ Fig. 2A] Fig. Figure 2A is a diagram that schematically shows a cross-sectional construction of a waveguide device 100, taken parallel to the XZ plane. [ Fig. 2B] Fig. Figure 2B is a diagram that schematically shows another cross-sectional construction of the waveguide device 100, taken parallel to the XZ plane. [ Fig. 3] Fig. Figure 3 is a perspective view that schematically shows the waveguide device 100, which is illustrated in such a way that the spacing between a conductive component 110 and a conductive component 120 is exaggerated for easier understanding. [ Fig. 4] Fig. 4 is a diagram showing an example dimensional range of each component in the Fig. The structure shown in 2A is shown. [ Fig. 5A] Fig. Figure 5A is a diagram that schematically shows an electromagnetic wave propagating in a narrow space, i.e., a gap between a waveguide surface 122a of a waveguide element 122 and a conductive surface 110a of a conductive element 110. [ Fig. 5B] Fig. 5B is a diagram that schematically shows a cross-section of a hollow waveguide 130. [ Fig. 5C] Fig. Figure 5C is a cross-sectional view showing an implementation in which two waveguide elements 122 are provided on the conductive element 120. [ Fig. 5D] Fig. 5D is a diagram that schematically shows a cross-section of a waveguide device in which two hollow waveguides 130 are arranged side by side. [ Fig. 6A] Fig. Figure 6A is a perspective view that schematically shows a partial construction of a slot array antenna 200 (comparative example) using a WRG structure. [ Fig. 6B] Fig. Figure 6B is a diagram schematically showing a partial cross-section passing through the centers of two slots 112 of a slot array antenna 200 arranged along the X direction, with the cross-section taken parallel to the XZ plane. [ Fig. 7A] Fig. Figure 7A is a perspective view schematically showing a partial construction of an antenna device 300 according to an illustrative embodiment of the present disclosure. [ Fig. 7B] Fig. Figure 7B is a diagram that schematically shows the positioning of a first conductive component 110 and a waveguide component 122, as well as a plurality of conductive rods 124 on it. [ Fig. 7C] Fig. 7C is a diagram that schematically shows a cross-section obtained by cutting the in Fig. The antenna device 300 shown in 7A is created on a plane which passes through the center of a slot 112 and is parallel to the XZ plane. [ Fig. 7D] Fig. 7D is a diagram schematically showing a cross-section obtained by cutting the antenna device 300 at a plane passing through the center of a slot 112 and parallel to the YZ plane. [ Fig. 8A] Fig. Figure 8A is a perspective view showing an example where a waveguide element 122 has a plurality of recesses 122d on the waveguide surface 122a. [ Fig. 8B] Fig. Figure 8B is a diagram showing a cross-section of a slotted antenna device 300 passing through the center of the slot 112 and parallel to the YZ plane. [ Fig. 9A] Fig. Figure 9A is a cross-sectional view schematically showing the structure of a slot array antenna according to a further embodiment of the present disclosure. [ Fig. 9B] Fig. Figure 9B is a cross-sectional view showing a slotted antenna device according to yet another embodiment. [ Fig. 9C] Fig. Figure 9C is a cross-sectional view that schematically shows the structure of a slot array antenna according to yet another embodiment of the present disclosure. [ Fig. 9D] Fig. Figure 9D is a cross-sectional view that schematically shows the structure of a slot array antenna according to yet another embodiment of the present disclosure. [ Fig. 9E] Fig. Figure 9E is a cross-sectional view that schematically shows the structure of a slot array antenna according to yet another embodiment of the present disclosure. [ Fig. 9F] Fig. Figure 9F is a cross-sectional view that schematically shows the structure of a slot array antenna according to yet another embodiment of the present disclosure. [ Fig. 10] Fig. Figure 10 is a graph showing the dependence of the waveguide's capacitance in the Fig. The construction shown in Figure 9C is from the Y-direction. [ Fig. 11] Fig. Figure 11 is a graph showing the dependence of the waveguide's capacitance in the Fig. The construction shown in Figure 9F schematically illustrates the Y-direction. [ Fig. 12] Fig. Figure 12 is a cross-sectional view which schematically shows yet another embodiment of the present disclosure. [ Fig. 13A] Fig. Figure 13A is a cross-sectional view which schematically shows yet another embodiment of the present disclosure. [ Fig. 13B] Fig. Figure 13B is a cross-sectional view which schematically shows yet another embodiment of the present disclosure. [ Fig. 13C] Fig. Figure 13C is a cross-sectional view which schematically shows yet another embodiment of the present disclosure. [ Fig. 13D] Fig. Figure 13D is a cross-sectional view that schematically shows yet another embodiment of the present disclosure. [ Fig. 14A] Fig. Figure 14A is a diagram showing yet another structure for the waveguide component 122. [ Fig. 14B] Fig. Figure 14B is a diagram showing yet another structure for the waveguide component 122. [ Fig. 15A] Fig. Figure 15A is a top view schematically showing a partial construction of an antenna device 300 according to a first embodiment of the present disclosure. [ Fig. 15B] Fig. Figure 15B is a perspective view showing more specifically the structure of a first conductive component 110 of the antenna device 300 and a waveguide component 122 on it. [ Fig. 15C] Fig. Figure 15C is a diagram schematically showing a cross-sectional structure of the antenna device 300, taken from a cross-section passing through the centers of a plurality of slots 112 and parallel to the YZ plane. [ Fig. 15D] Fig. Figure 15D is a perspective view showing two adjacent beam elements from the plurality of beam elements in embodiment 1. [ Fig. 16A] Fig. Figure 16A is a top view showing a partial construction of an antenna device 300 according to embodiment 2. [ Fig. 16B] Fig. 16B is a perspective view showing two of four beam elements. [ Fig. 17] Fig. Figure 17 is a perspective view showing two beam elements according to a variant of embodiment 2. [ Fig. 18A] Fig. Figure 18A is a perspective view showing a beam element according to a further variant of embodiment 2. [ Fig. 18B] Fig. Figure 18B is a perspective view showing the interior of a beam element according to a further variant of embodiment 2. [ Fig. 19] Fig. Figure 19 is a diagram showing a first conductive component 110 of a slotted antenna device 300, in which a plurality of horns 114 are each provided around a plurality of H-shaped slots 112, seen from the rear. [ Fig. 20] Fig. 20 is a cross-sectional view along line BB in Fig. 19. [ Fig. 21A] Fig. Figure 21A is a cross-sectional view that schematically shows the construction of an antenna device 300 according to embodiment 3. [ Fig. 21B] Fig. Figure 21B is a cross-sectional view showing a first variant of embodiment 3. [ Fig. 21C] Fig. Figure 21C is a cross-sectional view showing another variant of embodiment 3. [ Fig. 22] Fig. Figure 22 is a perspective view showing an example antenna device 300 with a plurality of waveguide components 122. [ Fig. 23] Fig. Figure 23 is a diagram for a more specific description of examples of cross-sectional shapes of a port 145 or of slots 111, 112. [ Fig. 24A] Fig. Figure 24A is a cross-sectional view showing an example structure in which only a waveguide surface 122a, which defines an upper surface of the waveguide element 122, is electrically conductive, while any other section of the waveguide element 122 other than the waveguide surface 122a is not electrically conductive. [ Fig. 24B] Fig. 24B is a diagram showing a variant in which the waveguide element 122 is not formed on the conductive element 120. [ Fig. 24C] Fig. Figure 24C is a diagram showing an example structure in which the conductive element 120, the waveguide element 122 and each of the plurality of conductive rods 124 are formed from a dielectric surface coated with an electrically conductive material such as a metal. [ Fig. 24D] Fig. Figure 24D is a diagram showing an example structure in which dielectric layers 110c and 120c are provided on the outermost surfaces of conductive components 110 and 120, a waveguide component 122 and conductive rods 124. [ Fig. 24E] Fig. Figure 24E is a diagram showing another example structure in which dielectric layers 110c and 120c are provided on the outermost surfaces of conductive components 110 and 120, a waveguide component 122 and conductive rods 124. [ Fig. 24F] Fig. 24F is a diagram showing an example where the height of the waveguide element 122 is lower than the height of the conducting rods 124 and a section of a conducting surface 110a of the conducting element 110, opposite to the waveguide surface 122a, protrudes towards the waveguide element 122. [ Fig. 24G] Fig. 24G is a diagram showing an example where the structure continues to consist of Fig. 24F Sections of the conductive surface 110a, which are opposite to the conductive bars 124, protrude in the direction of the conductive bars 124. [ Fig. 25A] Fig. Figure 25A is a diagram showing an example where a conductive surface 110a of the conductive component 110 is shaped as a curved surface. [ Fig. 25B] Fig. Figure 25B is a diagram showing an example where a conductive surface 120a of the conductive component 120 is also shaped as a curved surface. [ Fig. 26] Fig. Figure 26 is a diagram showing a vehicle 500 and a vehicle 502 ahead of it on the same lane as the vehicle 500. [ Fig. 27] Fig. Figure 27 is a diagram showing an on-board radar system 510 of the own vehicle 500. [ Fig. 28A] Fig. Figure 28A is a diagram showing a relationship between an array antenna AA of the 510 onboard radar system and several incoming waves k. [ Fig. 28B] Fig. Figure 28B is a diagram showing the array antenna AA receiving the k-th arriving wave. [ Fig. 29] Fig. Figure 29 is a block diagram showing an example basic construction of a vehicle driving control device 600 according to the present disclosure. [ Fig. 30] Fig. Figure 30 is a block diagram showing another example construction for the vehicle driving control unit 600. [ Fig. 31] Fig. Figure 31 is a block diagram showing an example of a more specific construction of the vehicle driving control unit 600. [ Fig. 32] Fig. Figure 32 is a block diagram showing a more detailed example construction of the radar system 510 according to this application example. [ Fig. 33] Fig. Figure 33 is a diagram showing the change in frequency of a transmit signal modulated on the basis of the signal generated by a triangle wave generation circuit 581. [ Fig. 34] Fig. Figure 34 is a diagram showing a beat frequency fu in a “rising” period and a beat frequency fd in a “falling” period. [ Fig. 35] Fig. Figure 35 is a diagram showing an example implementation where a signal processing circuit 560 is implemented in hardware with a processor PR and a storage device MD. [ Fig. 36] Fig. Figure 36 is a diagram showing a relationship between three frequencies f1, f2 and f3. [ Fig. 37] Fig. Figure 37 is a diagram showing a ratio between synthetic spectra F1 to F3 on a complex plane. [ Fig. 38] Fig. Figure 38 is a flowchart showing the procedure of a determination process for relative velocity and distance. [ Fig. 39] Fig. Figure 39 is a diagram of a combined installation containing a radar system 510 with a slotted array antenna and an onboard camera system 700. [ Fig. 40] Fig. Figure 40 is a diagram illustrating how placing a millimeter wave radar 510 and a camera in essentially the same position in the vehicle space can enable them to capture an identical field of view and line of sight, thus facilitating a matching process. [ Fig. 41] Fig. Figure 41 is a diagram showing an example design for a 1500-series surveillance system based on millimeter wave radar. [ Fig. 42] Fig. Figure 42 is a block diagram showing a design for a digital communication system 800A. [ Fig. 43] Fig. Figure 43 is a block diagram showing an example communication system 800B with a transmitter 810B that is capable of changing its radio wave emission pattern. [ Fig. 44] Fig. Figure 44 is a block diagram showing an example communication system 800C which implements a MIMO function. DESCRIPTION OF EXECUTION FORMS

[0008] Before describing embodiments of the present disclosure, a description of findings that form the basis of the present disclosure is given.

[0009] A ribbed waveguide, disclosed in the aforementioned patent documents 1 to 3 and non-patent documents 1 and 2, is provided in a waffle-iron structure capable of functioning as an artificial magnetic conductor. A ribbed waveguide utilizing such an artificial magnetic conductor based on the present disclosure (hereinafter also referred to as WRG, waffle-iron ribbed waveguide) is capable of realizing a low-loss antenna feed network in the microwave or millimeter-wave band. Furthermore, the use of such a ribbed waveguide allows for the arrangement of high-density antenna elements. An example of a basic design and operation of such a waveguide structure is described below.

[0010] An artificial magnetic conductor is a structure that artificially replicates the properties of a perfect magnetic conductor (PMC), which does not occur in nature. One property of a perfect magnetic conductor is that "a magnetic field on its surface has a tangential component of zero." This property is the opposite of the property of a perfect electrical conductor (PEC), namely that "an electric field on its surface has a tangential component of zero." Although a perfect magnetic conductor does not occur in nature, it can be created using an artificial structure, such as a multitude of electrically conductive rods. An artificial magnetic conductor functions as a perfect magnetic conductor within a specific frequency band defined by its structure.An artificial magnetic conductor restricts or prevents the propagation of an electromagnetic wave of any frequency contained within a specific frequency band (propagation-restricted band) along its surface. Therefore, the surface of an artificial magnetic conductor can be described as a high-impedance surface.

[0011] In the waveguide devices disclosed in patent documents 1 to 3 and non-patent documents 1 and 2, an artificial magnetic conductor is realized by a plurality of electrically conductive rods arranged in an array along row and column directions. Such rods are projections that may also be referred to as pillars or pins. Each of these waveguide devices comprises a pair of opposing electrically conductive plates. One conductive plate has a rib projecting toward the other conductive plate and extensions of an artificial magnetic conductor extending on both sides of the rib. An upper surface of the rib (i.e., its electrically conductive surface) faces across a gap toward an electrically conductive surface of the other conductive plate.An electromagnetic wave (signal wave) with a wavelength contained within the propagation-restricted band of the artificial magnetic conductor propagates along the rib in the space (interspace) between this conductive surface and the upper surface of the rib.

[0012] Fig. Figure 1 is a perspective view that schematically shows a non-restrictive example of a basic construction of such a waveguide device. Fig. Figure 1 shows XYZ coordinates along the X, Y, and Z directions, which are orthogonal to each other. The waveguide device 100 shown in the figure has a plate-like electrically conductive component 110 and a plate-shaped (plate-like) electrically conductive component 120, which are located in opposite and parallel positions. A plurality of electrically conductive rods 124 are arranged in an array on the conductive component 120.

[0013] It is noted that each structure depicted in a figure of the present application is shown in an orientation chosen for the sake of simplicity, which is not intended to restrict its orientation in any way when actually carrying out an embodiment of the present disclosure. Furthermore, the shape and size of any whole or part of any structure shown in a figure are not intended to restrict its actual shape and size.

[0014] Fig. 2A is a diagram showing the structure of a cross-section of the waveguide device 100 in Fig. 1, taken parallel to the XZ plane, schematically shows. As in Fig. As shown in Figure 2A, the conductive element 110 has an electrically conductive surface 110a on the side facing the conductive element 120. The conductive surface 110a has a two-dimensional extent along a plane that is orthogonal to the axial direction (i.e., the Z-direction) of the conductive rods 124 (i.e., a plane parallel to the XY-plane). Although the conductive surface 110a is shown as a smooth plane in this example, it need not be a plane, as will be described later.

[0015] Fig. Figure 3 is a perspective view schematically showing the construction of the waveguide device 100, illustrated in such a way that the spacing between the conducting element 110 and the conducting element 120 is exaggerated for easier understanding. In an actual waveguide device 100, as in Fig. 1 and Fig. As shown in 2A, the spacing between the conducting member 110 and the conducting member 120 is narrow, with the conducting member 110 covering all the conducting bars 124 on the conducting member 120.

[0016] Fig. 1 to Fig. Figure 3 shows only sections of the waveguide device 100. In fact, the conductive elements 110 and 120, the waveguide elements 122, and the plurality of conductive bars 124 extend beyond the sections illustrated in the figures. At one end of the waveguide element 122, as described below, a choke structure is provided to prevent electromagnetic waves from leaking into the external space. The choke structure can, for example, comprise a series of conductive bars adjacent to the end of the waveguide element 122.

[0017] See again Fig. 2A. The plurality of conductive rods 124, arranged in an array on the conductive element 120, each have a leading end 124a that faces away from the conductive surface 110a. In the example shown in the figure, the leading ends 124a of the plurality of conductive rods 124 are located on the same plane. This plane defines the surface 125 of an artificial magnetic conductor. Each conductive rod 124 need not be completely electrically conductive, as long as it has at least one electrically conductive layer extending along the top and side surfaces of the rod-like structure. This electrically conductive layer can be located on the surface layer of the rod-like structure, but the surface layer can also be formed from an insulating coating or a resin layer without an electrically conductive layer existing on the surface of the rod-like structure.Furthermore, each conductive element 120 need not be completely electrically conductive, as long as it can support the plurality of conductive bars 124 to form an artificial magnetic conductor. Of the surfaces of the conductive element 120, an area 120a supporting the plurality of conductive bars 124 can be electrically conductive, such that the electrical conductor electrically connects the surfaces of adjacent conductive bars 124. Additionally, the electrically conductive layer of the second conductive element 120 can be covered with an insulating coating or a resin layer. In other words, the entire combination of the conductive element 120 and the plurality of conductive bars 124 can have at least one electrically conductive layer with rises and depressions that are opposite to the conductive surface 110a of the conductive element 110.

[0018] On the conductive element 120, a rib-like waveguide element 122 is provided between the plurality of conductive rods 124. In particular, extensions of an artificial magnetic conductor are present on both sides of the waveguide element 122, so that the waveguide element 122 is arranged sandwich-like between the extensions of the artificial magnetic conductor on both sides. As shown in the figure Fig. As can be seen in Figure 3, the waveguide element 122 in this example is supported on the conductive element 120 and extends in a straight line along the Y-direction. In the example shown in the figure, the waveguide element 122 has the same height and width as those of the conductive rods 124. However, as will be described later, the height and width of the waveguide element 122 can also have different values ​​than those of the conductive rod 124. Unlike the conductive rods 124, the waveguide element 122 extends along a direction (in this example along the Y-direction) in which electromagnetic waves are to be guided along the conductive surface 110a. Likewise, the waveguide element 122 does not need to be completely electrically conductive, but can have at least one electrically conductive waveguide surface 122a that is opposite to the conductive surface 110a of the conductive element 110.The conductive element 120, the plurality of conductive rods 124, and the waveguide element 122 can be parts of a continuous, one-piece body. Furthermore, the conductive element 110 can also be part of such a one-piece body.

[0019] On both sides of the waveguide element 122, the space between the surface 125 of each extension of an artificial magnetic conductor and the conductive surface 110a of the conductive element 110 prevents the propagation of an electromagnetic wave of a frequency that lies within a specific frequency band. This frequency band is referred to as the "forbidden band." The artificial magnetic conductor is designed such that the frequency of an electromagnetic wave (signal wave) (hereinafter also referred to as the "operating frequency") for propagation in the waveguide device 100 is contained within the forbidden band. The forbidden band is adjustable based on the following: the height of the conductive rods 124, i.e.,the depth of each depression formed between adjacent conducting bars 124; the width of each conducting bar 124; the interval between the conducting bars 124; and the size of the space between the conducting end 124a and the conducting surface 110a of each conducting bar 124.

[0020] Next, with reference to Fig. 4. Dimensions, shape, positioning and the like of each component are described.

[0021] Fig. 4 is a diagram showing an example dimensional range of each component in the Fig. The structure shown in Figure 2A is shown. The waveguide device is used at least for either transmitting or receiving electromagnetic waves of a predetermined band (referred to as the "operating frequency band"). In this specification, λo denotes a representative value for free-space wavelengths (e.g., a center wavelength corresponding to a center frequency in the operating frequency band) of an electromagnetic wave (signal wave) propagating in a waveguide extending between the conductive surface 110a of the conductive element 110 and the waveguide area 122a of the waveguide element 122. Furthermore, λm denotes a free-space wavelength of an electromagnetic wave of the highest frequency in the operating frequency band. The end of each conductive rod 124 in contact with the conductive element 120 is referred to as the "root". As shown in Fig. As shown in Figure 4, each conducting rod 124 has a leading end 124a and a root 124b. Examples of dimensions, shapes, positioning, and the like of the respective structural members are as follows. (1) Width of the leading staff

[0022] The width (i.e., the size along the X and Y directions) of the conducting bar 124 can be set to less than λm / 2. Within this range, the occurrence of lowest-order resonance along the X and Y directions can be prevented. Since resonance may occur not only in the X and Y directions but also in any diagonal direction in an XY cross-section, the diagonal length of an XY cross-section of the conducting bar 124 is preferably also less than λm / 2. The lower limits for the width and diagonal length of the bar correspond to the minimum lengths that can be produced with the given manufacturing process but are not specifically restricted. (2) Distance from the root of the conducting rod to the conducting surface of the conducting component

[0023] The distance from the root 124b of each conducting rod 124 to the conducting surface 110a of the conducting component 110 can be longer than the height of the conducting rods 124, but less than λm / 2. If the distance is λm / 2 or greater, resonance can occur between the root 124b of each conducting rod 124 and the conducting surface 110a, which reduces the signal wave attenuation effect.

[0024] The distance from the root 124b of each conducting rod 124 to the conducting surface 110a of the conducting element 110 corresponds to the spacing between the conducting element 110 and the conducting element 120. For example, if a signal wave of 76.5 ± 0.5 GHz (belonging to the millimeter band or the extremely high frequency band) propagates in the waveguide, the wavelength of the signal wave is in the range of 3.8934 mm to 3.9446 mm. Therefore, λm in this case is 3.8934 mm, so the spacing between the conducting element 110 and the conducting element 120 can be set to less than half of 3.8934 mm. As long as the conductive component 110 and the conductive component 120 maintain such a narrow distance between them and are arranged in opposite directions, the conductive component 110 and the conductive component 120 do not need to be exactly parallel.If the spacing between the conductive element 110 and the conductive element 120 is less than λm / 2, then all or part of the conductive element 110 and / or the conductive element 120 can be shaped as a curved surface. Furthermore, the conductive elements 110 and 120 each have a planar shape (i.e., the shape of their region projected perpendicularly onto the XY plane) and a planar size (i.e., the size of their region projected perpendicularly onto the XY plane), which can be arbitrarily designed depending on the purpose.

[0025] Although the conductive surface 120a in the Fig. As the example shown in 2A illustrates as a plane, embodiments of the present disclosure are not limited to this. As shown in Fig. As shown in Figure 2B, the conductive surface 120a can, for example, be the lower parts of surfaces, each having a cross-section similar to a U-shape or a V-shape. The conductive surface 120a has such a structure if each conductive rod 124 or waveguide element 122 is shaped with a width that increases towards the root. The conductive surface 120a can also be formed with such a structure if it is shaped as shown in Figure 2B. Fig. The device shown in 2B functions as the waveguide device according to an embodiment of the present disclosure, as long as the distance between the conductive surface 110a and the conductive surface 120a is less than half the wavelength λm. (3) Distance L2 from the leading end of the conducting rod to the conducting surface

[0026] The distance L2 from the leading end 124a of each conducting rod 124 to the conducting surface 110a is set to less than λm / 2. If the distance is λm / 2 or more, a propagation mode can occur in which electromagnetic waves move back and forth between the leading end 124a of each conducting rod 124 and the conducting surface 110a, making containment of an electromagnetic wave impossible. It is noted that, at least in the case of the plurality of conducting rods 124 adjacent to the waveguide element 122, the leading ends are not in electrical contact with the conducting surface 110a.That the leading end of a conducting rod is not in electrical contact with the conducting surface means, as used here, one of the following conditions: There is an air gap between the leading end and the conducting surface; or the leading end of the conducting rod and the conducting surface are separated by an insulating layer, which may exist in the leading end of the conducting rod or in the conducting surface. (4) Arrangement and shape of the conducting rods

[0027] The gap between two adjacent conducting bars 124 from the plurality of conducting bars 124, for example, has a width of less than λm / 2. The width of the gap between any two adjacent conducting bars 124 is defined by the shortest distance from the surface (side face) of one of the two conducting bars 124 to the surface (side face) of the other. This width of the gap between the bars must be determined such that no lowest-order resonance occurs in the regions between the bars. The conditions under which resonance occurs are determined based on a combination of the following: the height of the conducting bars 124; the distance between any two adjacent conducting bars; and the capacitance of the air gap between the leading end 124a of each conducting bar 124 and the conducting surface 110a.Therefore, the width of the gap between the bars can be appropriately determined according to other design parameters. Although there is no clear lower limit for the width of the gap between the bars, it can be, for example, λm / 16 or more for easier manufacturing if propagation of an electromagnetic wave in the extremely high frequency range is required. It should be noted that the gap need not have a constant width. As long as it remains less than λm / 2, the gap between the conductive bars 124 can vary.

[0028] The arrangement of the plurality of conducting bars 124 is not limited to the illustrated example, as long as it functions as an artificial magnetic conductor. The plurality of conducting bars 124 need not be arranged in orthogonal rows and columns; the rows and columns may also intersect at angles other than 90 degrees. The plurality of conducting bars 124 need not form a linear array along rows or columns, but may have a scattered arrangement that does not exhibit a simple regularity. The conducting bars 124 may also vary in shape and size depending on their position on the conducting element 120.

[0029] The surface 125 of the artificial magnetic conductor, formed by the leading ends 124a of the plurality of conducting rods 124, need not be a perfectly flat plane, but can be a plane with very small rises and dips or even a curved surface. The conducting rods 124 need not be of uniform height; rather, the conducting rods 124 can be of different heights, as long as the array of conducting rods 124 functions as an artificial magnetic conductor.

[0030] Each conducting rod 124 need not have a prismatic shape, as shown in the figure, but can, for example, also have a cylindrical shape. Furthermore, each conducting rod 124 need not have a simple column shape. The artificial magnetic conductor can also be realized by any structure other than an array of conducting rods 124, and various artificial magnetic conductors are applicable to the waveguide device of the present disclosure. It is noted that if the leading end 124a of each conducting rod 124 has a prismatic shape, its diagonal length is preferably less than λm / 2. If the leading end 124a of each conducting rod 124 is shaped as an ellipse, the length of its major axis is preferably less than λm / 2. For any other shape of the leading end 124a, the dimension above it, even at its longest position, is preferably less than λm / 2.

[0031] The height of each conducting rod 124 (especially the conducting rods 124 adjacent to the waveguide element 122), i.e. the length from the root 124b to the leading end 124a, can be set to a value that is shorter than the distance (i.e. less than λm / 2) between the conducting surface 110a and the conducting surface 120a, e.g. λ0 / 4. (5) Width of the waveguide area

[0032] The width of the waveguide area 122a of the waveguide element 122, i.e., the size of the waveguide area 122a along a direction orthogonal to the direction in which the waveguide element 122 extends, can be set to less than λm / 2 (e.g., λm / 8). If the width of the waveguide area 122a is λm / 2 or greater, resonance occurs along the width direction, which prevents any waveguide element from functioning as a simple transmission line. (6) Height of the waveguide component

[0033] The height of the waveguide element 122 (i.e., in the example shown in the figure, the dimension along the Z-direction) is set to less than λm / 2. The reason for this is that at a distance of λm / 2 or more, the distance between the root 124b of each conducting bar 124 and the conducting surface 110a is λm / 2 or more. Likewise, the height of the conducting bars 124 (especially those conducting bars 124 adjacent to the waveguide element 122) is also set to less than λm / 2. (7) Distance L1 between the waveguide surface and the conducting surface

[0034] The distance L1 between the waveguide surface 122a of the waveguide element 122 and the conductive surface 110a is set to less than λm / 2. If the distance is λm / 2 or greater, resonance occurs between the waveguide surface 122a and the conductive surface 110a, preventing its functionality as a waveguide. In one example, the distance L1 is λm / 4 or less. To ensure ease of manufacturing, the distance L1 is preferably, for example, λm / 16 or greater, when an electromagnetic wave is to propagate in the extremely high frequency range.

[0035] The lower limit of the distance L1 between the conductive surface 110a and the waveguide surface 122a, as well as the lower limit of the distance L2 between the conductive surface 110a and the leading end 124a of each conductive rod 124, depend on the machining accuracy and also on the accuracy of assembling the two upper / lower conductive components 110 and 120 such that they are separated by a constant distance. When using a pressing or injection molding technique, the practical lower limit of this distance is approximately 50 micrometers (µm). When using a MEMS (microelectromechanical system) technique to manufacture a product, e.g., in the terahertz range, the lower limit for the aforementioned distance is approximately 2 to 3 µm.

[0036] In the waveguide device 100 with the construction described above, a signal wave at the operating frequency cannot propagate in the space between the surface 125 of the artificial magnetic conductor and the conductive surface 110a of the conductive element 110, but rather propagates in the space between the waveguide surface 122a of the waveguide element 122 and the conductive surface 110a of the conductive element 110. Unlike a hollow waveguide, the width of the waveguide element 122 in such a waveguide structure does not need to be equal to or greater than half the wavelength of the electromagnetic wave to be propagated. Furthermore, the conductive element 110 and the conductive element 120 do not need to be connected by a metal wall extending along the thickness direction (i.e., parallel to the YZ plane).

[0037] Fig. Figure 5A schematically shows an electromagnetic wave propagating in a narrow space, i.e., an intermediate space between the waveguide surface 122a of the waveguide element 122 and the conductive surface 110a of the conductive element 110. Fig. Figure 5A shows three arrows schematically indicating the orientation of an electric field of the propagating electromagnetic wave. The electric field of the propagating electromagnetic wave is perpendicular to the conducting surface 110a of the conducting component 110 and to the waveguide surface 122a.

[0038] On both sides of the waveguide element 122 are extensions of an artificial magnetic conductor, generated by the plurality of conducting rods 124. An electromagnetic wave propagates in the space between the waveguide surface 122a of the waveguide element 122 and the conducting surface 110a of the conducting element 110. Fig. Figure 5A is schematic and does not accurately represent the magnitude of an electromagnetic field that is actually generated by the electromagnetic wave. A portion of the electromagnetic wave (electromagnetic field) propagating in the space above the waveguide surface 122a may have a lateral extension beyond the space bounded by the width of the waveguide surface 122a (i.e., towards where the artificial magnetic conductor exists). In this example, the electromagnetic wave propagates in a direction (i.e., the Y-direction) that extends towards the plane formed by Fig. 5A is perpendicular. As such, the waveguide element 122 does not need to extend linearly along the Y-direction, but can have one or more bends and / or one or more branching sections (not shown). Since the electromagnetic wave propagates along the waveguide surface 122a of the waveguide element 122, the direction of propagation would change at a bend, while the direction of propagation would branch out in several directions at a branching section.

[0039] In the waveguide structure made of Fig. 5A There is no metal wall (electrical wall), which would be essential for a hollow waveguide, on either side of the propagating electromagnetic wave. Therefore, in the waveguide structure from this example, "a restriction due to a metal wall (electrical wall)" is not included in the boundary conditions for the electromagnetic field mode to be generated by the propagating electromagnetic wave, and the width (size along the X-direction) of the waveguide area 122a is less than half the wavelength of the electromagnetic wave.

[0040] As a reference, it shows Fig. Figure 5B schematically shows a cross-section of a hollow waveguide 130. Arrows indicate Fig. Figure 5B schematically shows the orientation of an electric field of an electromagnetic field mode (TE10) generated in the inner space 132 of the hollow waveguide 130. The lengths of the arrows correspond to electric field strengths. The width of the inner space 132 of the hollow waveguide 130 must be set wider than half the wavelength. In other words, the width of the inner space 132 of the hollow waveguide 130 cannot be set smaller than half the wavelength of the propagating electromagnetic wave.

[0041] Fig. Figure 5C is a cross-sectional view showing an implementation in which two waveguide elements 122 are provided on the conductive element 120. Thus, an artificial magnetic conductor exists between the two adjacent waveguide elements 122, generated by the plurality of conductive bars 124. More precisely, extensions of an artificial magnetic conductor generated by the plurality of conductive bars 124 are located on both sides of each waveguide element 122, so that each waveguide element 122 can propagate an electromagnetic wave independently.

[0042] As a reference, it shows Fig. Figure 5D schematically shows a cross-section of a waveguide device in which two hollow waveguides 130 are arranged side by side. The two hollow waveguides 130 are electrically isolated from each other. Each chamber in which an electromagnetic wave is to propagate must be surrounded by a metal wall that defines the respective hollow waveguide 130. Therefore, the interval between the inner chambers 132 in which electromagnetic waves are to propagate cannot be smaller than the combined thickness of the two metal walls. Usually, the combined thickness of two metal walls is greater than half the wavelength of a propagating electromagnetic wave. The interval between the hollow waveguides 130 (i.e., the interval between their centers) can therefore only be difficult to make shorter than the wavelength of a propagating electromagnetic wave. This is especially true for electromagnetic waves with wavelengths in the extremely high frequency range (i.e.,For electromagnetic wave wavelengths of 10 mm or less, or even shorter wavelengths, it is difficult to create a metal wall that is sufficiently thin relative to the wavelength. This poses a cost problem for commercially viable implementation.

[0043] In contrast, a waveguide device 100, which has an artificial magnetic conductor, can easily be used to create a structure in which waveguide elements 122 are arranged close together. Thus, such a waveguide device 100 is suitable for use in an array antenna that has several antenna elements in a close arrangement.

[0044] Fig. Figure 6A is a perspective view that schematically shows an example construction of a slot array antenna 200 (comparative example) using the waveguide structure described above. Fig. Figure 6B is a diagram schematically showing a partial cross-section passing through the centers of two slots 112 of a slotted array antenna 200 arranged along the X-direction, with the cross-section taken parallel to the XZ plane. In the slotted array antenna 200, the first conductive element 110 has a plurality of slots 112 arranged in an array along the X- and Y-directions. In this example, the plurality of slots 112 has two rows of slots. Each row of slots has six slots 112 arranged at equal intervals along the Y-direction. On the second conductive element 120, two waveguide elements 122 are provided, extending along the Y-direction. Each waveguide element 122 has an electrically conductive waveguide surface 122a facing opposite a row of slots.In the region between the two waveguide elements 122 and in the regions outside the two waveguide elements 122, a plurality of conductive rods 124 are provided. The conductive rods 124 form an artificial magnetic conductor.

[0045] An electromagnetic wave from a transmitting circuit (not shown) is fed into the waveguide, which extends between the waveguide surface 122a of each waveguide element 122 and the conductive surface 110a of the conductive element 110. Among the plurality of slots 112 arranged along the Y-direction, the distance between the centers of any two adjacent slots 112 is designed to have, for example, the same value as the wavelength of an electromagnetic wave propagating in the waveguide. Consequently, electromagnetic waves of the same phase are emitted from the six slots 112 arranged along the Y-direction.

[0046] The in Fig. 6A and Fig. The slotted array antenna 200 shown in Figure 6B is an antenna array whose beaming elements are the plurality of slots 112. With this design of the slotted array antenna 200, the interval between the centers of the beaming elements along the X-direction can be made shorter, for example, than the wavelength λ0 in free space of an electromagnetic wave propagating in the waveguide.

[0047] The inventors have found that a low-loss antenna device can be realized by a structure that differs from that of the slotted array antenna 200 described above. An example construction of an embodiment of the present disclosure is described below. <Beispielkonstruktion einer Schlitzantennenvorrichtung>

[0048] First, with reference to Fig. Sections 7A to 7D describe the construction of a slotted antenna device 300 (hereinafter also referred to simply as "antenna device 300") according to an illustrative embodiment of the present disclosure. For practical reasons, in the present disclosure, "the front" refers to the side that borders the free space in which an electromagnetic wave radiated from or incident upon the antenna device 300 is intended to propagate; the opposite side is referred to as "the back". In the present disclosure, terms such as "first", "second", etc., are used only to distinguish between components, devices, parts, sections, layers, regions, or the like, without implying any limitations of meaning.

[0049] Fig. Figure 7A is a perspective view schematically showing a partial construction of the antenna device 300 according to an illustrative embodiment of the present disclosure. The antenna device 300 has a first conductive element 110 and a second conductive element 120, which are opposite to each other. The first conductive element 110 has a slot 112. In this embodiment, unlike in the comparative example described above, a waveguide element 122 and a plurality of conductive rods 124 are connected to the first conductive element 110 instead of to the second conductive element 120.

[0050] Fig. Figure 7B schematically shows the positioning of the first conductive element 110 and the waveguide element 122, as well as the plurality of conductive bars 124 on it. The waveguide element 122, which is a rib-shaped element provided on the first conductive element 110 and has an electrically conductive surface, is divided at the position of the slot 112 into a first rib 122A and a second rib 122B. In this example, the first rib 122A and the second rib 122B each have a projection 122b in their central section.

[0051] Fig. 7C is a diagram that schematically shows a cross-section obtained by cutting the in Fig. The antenna device 300 shown in 7A is created on a plane that passes through the center of a slot 112 and is parallel to the XZ plane. Fig. Figure 7D is a diagram schematically showing a cross-section obtained by cutting the antenna device 300 at a plane passing through the center of a slot 112 and parallel to the YZ plane. Fig. Figure 7D shows only a cross-section of the waveguide component 122, shaded. A similar representation can also be used in any of the following figures.

[0052] The first conductive element 110 has a first conductive surface 110b on the front side and a second conductive surface 110a on the back side. The first conductive element 110 has at least one slot 112 extending from the first conductive surface 110b to the second conductive surface 110a. Although the first conductive element 110 is illustrated with only one slot 112 in this example, the first conductive element 110 can have a plurality of slots 112, as is the case in the comparative example described above.

[0053] The second conductive element 120 is arranged on the back side of the first conductive element 110. The second conductive element 120 has a third conductive surface 120a on its front side, the third conductive surface 120a being opposite to the second conductive surface 110a.

[0054] As in Fig. As shown in Figure 7D, the waveguide element 122 is located on the second conductive surface 110a of the first conductive element 110. The waveguide element 122 has an electrically conductive waveguide surface 122a that is opposite to the third conductive surface 120a of the second conductive element 120. The waveguide element 122 extends along the third conductive surface 120a. The waveguide surface 122a of the waveguide element 122 has a strip shape (also referred to as a "band shape") that extends along the third conductive surface 120a.

[0055] In this specification, "strip shape" refers to a shape defined by a single stripe, rather than one formed by multiple stripes. Not only shapes extending linearly in one direction, but also any shape that bends or branches along its length is included in the definition of "strip shape." Similarly, if the waveguide surface 122a has a section that undergoes a change in height or width, the shape falls under the meaning of "strip shape" as long as it has a section that extends in only one direction when viewed from the normal direction of the waveguide surface 122a.

[0056] The artificial magnetic conductor in the present embodiment comprises a plurality of conductive rods 124. The artificial magnetic conductor extends on both sides of the waveguide element 122 and suppresses the leakage of an electromagnetic wave propagating along the waveguide element 122. As shown in Fig. As shown in Figure 7C, the artificial magnetic conductor is located on the second conductive surface 110a. Without being limited to this example, the artificial magnetic conductor can also be located on the third conductive surface 120a. The artificial magnetic conductor can exist on at least either the second conductive surface 110a or the third conductive surface 120a.

[0057] The third conductive surface 120a, the waveguide surface 122a, and the artificial magnetic conductor define a waveguide in a space extending between the third conductive surface 120a and the waveguide surface 122a. This waveguide is connected to the external space via the slot 112. In other words, the slot 112 is open to the external space.

[0058] As in Fig. 7B and Fig. As shown in Figure 7D, the waveguide element 122 has the first rib 122A and the second rib 122B extending along a common path. "Extending along a path" means extending along an imaginary path and can include not only extension along a straight line but also extension along a curve or a bent line. One end of the first rib 122A and one end of the second rib 122B are opposite each other. That the ends of two ribs are opposite each other means that these end faces of the ribs are arranged to face each other.

[0059] Viewed from a direction perpendicular to the waveguide surface 122a, the slot 112 is arranged between one end of the first rib 122A and one end of the second rib 122B. In the Fig. In the example shown in 7D, the end surfaces 122c of the first rib 122A and the second rib 122B, which are opposite to each other, with an inner wall surface 112c of the slot 112 continuous. In the example shown in Fig. In the example shown in 7D, the inner wall surface of slot 112 and the end faces 122c of ribs 122A and 122B, where they are continuously connected, are not shown stepped; however, they can alternatively be stepped.

[0060] The size of the gap between the end face 122c of the first rib 122A and the end face 122c of the second rib 122B can vary along a direction perpendicular to the waveguide surface 122a (i.e., the Z-direction). For example, to suppress reflection of signal waves, the size of the gap between the first rib 122A and the second rib 122B can be locally adjusted. The size of the gap between the two end faces 122c is designed such that the waveguide extending between the waveguide surface 122a and the third conductive surface 120a couples to the external space via the gap between the two end faces 122c and the interior of the slot 112.

[0061] The waveguide extending between the waveguide surface 122a of the first rib 122A and the third conductive surface 120a, or the waveguide extending between the waveguide surface 122a of the second rib 122B and the third conductive surface 120a, is used to connect to a transmitter or receiver (not shown). During transmission, an electromagnetic wave supplied from the transmitter propagates in the waveguide and passes between the two end surfaces 122c of the ribs 122A and 122B and through the interior of the slot 112 to be radiated into the external space. During reception, an electromagnetic wave arriving from the outside space at slot 112 passes through the interior of slot 112 and between the end faces 122c of ribs 122A and 122B and propagates along rib 122A or 122B to be received by the receiving circuit.

[0062] In this example, ribs 122A and 122B each have a protrusion 122b in their central section. The protrusion 122b narrows the interval between the waveguide surface 122a and the third conductive surface 120a. The protrusions 122b are designed to adjust the wavelength or phase of a signal wave propagating in the waveguide extending between the waveguide surface 122a and the third conductive surface 120a. The presence of the protrusions 122b locally increases the capacitance of the waveguide between the waveguide surface 122a and the third conductive surface 120a, thereby shortening the wavelength of the signal wave. Based on this effect, for example, during transmission, the phase of a signal wave at the position of slot 112 can be adjusted to achieve desired radiation characteristics.Such a structure is particularly effective in applications where, for example, in a construction where the first conductive element 110 has a plurality of slots 112 arranged along the Y-direction, all slots 112 are intended to radiate signal waves with the same phase. By providing the protrusions 122b, the wavelength of a signal wave in the waveguide is shortened, thereby reducing the intervals between the slots.

[0063] While not limited to a design in which protrusions 122b are provided on the waveguide surface 122a, such phase adjustment is also possible in other designs. For example, similar effects can also be achieved in a design in which at least one recess is provided on the waveguide surface 122a.

[0064] Fig. Figure 8A is a perspective view showing an example where the waveguide element 122 has a plurality of recesses 122d on the waveguide surface 122a. Fig. Figure 8A shows the first conductive component 110 and the waveguide component 122 on it, with an example arrangement of the ribs 122A and 122B and a plurality of conductive rods 124 on the waveguide component 122. Fig. Figure 8B is a diagram showing a cross-section of the slot antenna device 300 passing through the center of the slot 112 and parallel to the YZ plane.

[0065] In this example, the waveguide element 122 has a plurality of recesses 122d, which serve to widen the spacing between the waveguide surface 122a and the third conductive surface 120a. Two of the recesses 122d are provided between the central section of the first rib 122A and its opposite ends. Two further recesses 122d are provided between the central section of the second rib 122B and its opposite ends. By providing such recesses 122d on the waveguide surface 122a, the inductance of the waveguide extending between the waveguide surface 122a and the third conductive surface 120a is locally increased, which produces the effect of shortening the wavelength of a signal wave. Based on this effect, for example, during transmission, the phase of a signal wave at the position of each slot 112 can be adjusted to achieve desired radiation characteristics.

[0066] The protrusions 122b or recesses 122d in each of the above examples can be provided on the third conductive surface 120a instead of on the waveguide surface 122. Such a design achieves similar effects to a design in which the protrusions 122b or recesses 122d are provided on the waveguide surface 122a. The protrusions 122b or recesses 122d can be provided on either the waveguide surface 122a or the third conductive surface 120a.

[0067] The aforementioned effects of wavelength or phase adjustment can also be achieved if, instead of providing the protrusions 122b or recesses 122d, the width of the waveguide surface 122a is varied along its direction of extension. Creating wide sections where the width of the waveguide surface 122a is wider than at any adjacent point provides effects similar to those achieved by the protrusions 122b. Creating narrow sections where the width of the waveguide surface 122a is narrower than at any adjacent point provides effects similar to those achieved by the recesses 122d. Wavelength or phase adjustments similar to those described above are achieved with a design in which the waveguide element 122 has wider or narrower sections.A structure can also be used in which two or more of the raised sections, recesses, wide sections and narrow sections are combined.

[0068] Thus, in a slot antenna device according to one embodiment of the present disclosure, at least either the spacing between the waveguide surface 122a and the third conductive surface 120a or the width of the waveguide surface 122a is varied along a direction in which the waveguide element 122 or the waveguide extends. In one embodiment, at least either the second conductive element 120 or the waveguide element 122 has at least one protrusion or at least one recess. In another embodiment, the waveguide element 122 has at least one wide section or at least one narrow section. The spacing between the waveguide surface 122a and the third conductive surface 120a or the width of the waveguide surface 122a can be varied periodically or aperiodically along the direction in which the waveguide extends.The waveguide surface 122a and the third conductive surface 120a can assume a variety of structures depending on the radiation or reception characteristics that the slot antenna device 300 must fulfill. <Beispielkonstruktion einer Schlitzantennenvorrichtung mit mehreren Schlitzen>

[0069] The function of wavelength or phase adjustment according to one embodiment of the present disclosure is particularly effective in a slotted antenna device with a plurality of slots as radiating elements. Such a slotted antenna device is described in more detail below. Unless contradictory, the design of each of the examples described below is applicable to a slotted antenna device with a single slot. Furthermore, the designs of the examples described below can be used in combination. In the following description, a slotted antenna device may be referred to as a "slotted array antenna" or simply as an "array antenna".

[0070] Depending on its purpose, an array antenna can employ different methods to excite each beam element. For example, in a radar device using a waveguide, different methods are used to excite each beam element depending on the desired radar characteristics, such as maximizing radar efficiency or reducing side lobes at the cost of reduced efficiency. This document describes, as an example, a design method in which the gain of an array antenna is maximized to maximize its radar efficiency. To maximize the gain of an array antenna, it is known that the density at which the beam elements forming the array are arranged can be maximized, ensuring that all beam elements are excited with the same amplitude and phase. For example, standing wave series feeding can be used to achieve this.Standing wave series feeding is a feeding method in which all beam elements in an array antenna are excited with the same amplitude and phase by exploiting their property that "on a path where a standing wave is generated, identical voltages and currents exist at positions that are one wavelength apart."

[0071] This document describes a common design procedure for achieving a series standing wave feed. First, a waveguide is constructed such that an electromagnetic wave (signal wave) is allowed to undergo total internal reflection at at least one of the two ends of a feed path, thus generating a standing wave along the feed path. Next, at a multitude of positions along the feed path separated by one wavelength, a multitude of beam elements with identical impedances, small enough not to significantly affect the standing wave, are inserted in series, such that the standing wave current has its greatest amplitude at these positions. Consequently, an excitation with the same amplitude and phase is achieved based on a series standing wave feed.

[0072] The principle of series standing wave feeding is thus easily understood. However, it was found that simply applying such a design to a wave-feedback array antenna does not readily achieve excitation with the same amplitude and phase. The inventors' investigations revealed that to excite all beam elements with the same amplitude and phase, it is effective to adjust the phase of a signal wave propagating through the wave-feedback array by providing one or more sections on the array with a different capacitance or inductance than any other section.A different capacitance or inductance than at any other section can be achieved, for example, by introducing one or more sections where the distance between the waveguide area and the electrically conductive surface of an opposing conductive element, or the width of the waveguide area, differs relative to that at any adjacent location. Such phase settings are required not only when all beam elements are excited with the same amplitude and phase, but also to achieve other purposes, such as reducing side lobes at the cost of efficiency. For example, phase and amplitude differences can be introduced between adjacent beam elements to realize desired excitation states at the respective slot positions, or other settings can be implemented.Furthermore, similar phase settings are required not only when using a standing wave feed, but also when using a traveling wave feed.

[0073] In a conventional WRG-based array antenna, disclosed in the aforementioned patent document 1, identical recesses (holes) or wide sections are arranged along the entire path with a specific short period, and no structure is provided for adjusting the phase of the signal wave. In the design disclosed in patent document 1, at a given wavelength λ R a signal wave in a waveguide in which no recesses or wide sections are provided, periodically arranged recesses or wide sections with a period smaller than λ R / 4. Such a structure affects the characteristic impedance on the transmission line as a distributed constant circuit and consequently shortens the wavelength of the signal wave within the waveguide. However, it is not capable of adjusting the excitation state of each slot according to the desired antenna characteristics.

[0074] The reason is that when constructing a slotted array antenna by arranging a plurality of slots on the ribbed waveguide disclosed in patent document 1, the slot impedance is large enough to significantly distort the waveform of a signal wave propagating through the waveguide. Therefore, when using the very small periodic structure disclosed in patent document 1, it is presumably difficult to adjust the intensity and phase of an electromagnetic wave radiated from each of the plurality of slots according to the purpose. Thus, in a WRG-based radar device or the like, one cannot construct the waveguide and the slots independently of each other to achieve the desired radar characteristics. In other words, to achieve the desired properties, e.g.,To maximize efficiency or reduce side lobes at the cost of efficiency, the waveguide and the slots must both be optimized simultaneously. When one of the inventors filed the patent application according to patent document 1, such influences of the slot impedance were not yet recognized.

[0075] To achieve the desired antenna characteristics, the inventors considered introducing additional elements (e.g., recesses or protrusions) between two adjacent slots along the direction in which the waveguide element extends, at an interval longer than λ. R / 4. Furthermore, the inventors investigated an arrangement of additional elements, such as recesses or protrusions, between two adjacent slots in an aperiodic manner along the transmission line. Additionally, the inventors investigated a structure in which the spacing between the second conductive element and the waveguide element and / or the width of the waveguide area of ​​the waveguide element varies in three or more steps along the waveguide area (i.e., the inductance and / or capacitance varies). As a result, they succeeded in adjusting the wavelength of the signal wave within the waveguide and also in adjusting the intensity and phase of the propagating signal wave at the slots. λ R is longer than one wavelength λo in free space, but less than 1.15 λo. The aforementioned “interval longer than λ R / 4” can therefore also be read as “interval longer than 1.15λo / 4”. If the above-mentioned interval is greater than λ R If the difference is 1 / 4, but only by a small amount, a sufficient phase adjustment may not be achieved in the propagating signal wave. In such a case, a point can be introduced where additional elements are arranged at an interval equal to or greater than 1.5λo / 4.

[0076] In this specification, "add-on element" means a structure on a transmission line that locally modifies at least either the inductance or the capacitance. In this specification, "inductance" and "capacitance" refer to inductance and capacitance values ​​per unit length in one direction along the transmission line (i.e., the direction in which the waveguide element extends), where the unit length is equal to or less than 1 / 10 of the wavelength λo in free space. Without being limited to a recess or protrusion, an add-on element may, for example, be a "wide section" where the waveguide area has a greater width than in the other, adjacent sections, or a "narrow section" where the waveguide area has a smaller width than in the other, adjacent sections.Alternatively, it can be a section formed from a material whose dielectric constant differs from that of any other section. One or more such additional elements can be provided on an electrically conductive waveguide surface of a waveguide component or on a conductive surface of a conductive component that faces opposite the waveguide surface.

[0077] With reference to Fig. Sections 9A to 9F now describe example designs for slot array antennas according to illustrative embodiments of the present disclosure.

[0078] Fig. Figure 9A is a cross-sectional view schematically showing the structure of a slot array antenna according to an illustrative embodiment of the present disclosure. Fig. Figure 9A is a cross-sectional view obtained by cutting the slotted array antenna along a plane parallel to the YZ plane and extending through the center of the plurality of slots 112. A first conducting element 110 of this slotted array antenna has a plurality of slots 112 arranged along the Y direction. The waveguide element 122 extends along the Y direction and has a plurality of ribs arranged at intervals along the Y direction. Viewed from a direction perpendicular to the conducting surface 110a or the waveguide surface 122a, each of the plurality of slots 112 is located between opposite ends of two adjacent ribs from the plurality of ribs. In this example, the first conducting element 110 has three slots 112, while the waveguide element 122 has four ribs.The number of slots 112 and the number of ribs in the waveguide component 122 may differ from those illustrated in this example.

[0079] The waveguide element 122 is provided with a plurality of recesses. The positions of the recesses are chosen such that changes in the signal wave phase are introduced at the positions of the plurality of slots 112 to provide desired properties. In this example, the two recesses 122d1 and 122d2 are located in the second rib from the left at symmetrical positions with respect to an XZ plane extending through the midpoint between two adjacent slots 112 along the Y direction. The number, shapes, and sizes of the recesses, as well as their positions on the rib, differ from rib to rib. Therefore, it is not necessary for all ribs in the waveguide element 122 to be structurally identical.

[0080] During the construction from Fig. 9A features the plurality of recesses of the waveguide element 122, comprising a first recess 122d1, a second recess 122d2, and a third recess 122d3, which are adjacent in this order along the Y-direction. The distance between the centers of the first recess 122d1 and the second recess 122d2 differs from the distance between the centers of the second recess 122d2 and the third recess 122d3. Thus, in the Fig. In the construction shown in Figure 9A, at least in the region shown in the figure, the spacing between the second conductive surface 110a on the rear side of the first conductive element 110 and the waveguide surface 122a of the waveguide element 122 varies aperiodically along the Y-direction. The first to third recesses can be located at any position, as long as they are provided between the two outermost slots of the plurality of slots 112. The plurality of recesses can instead be provided on the third conductive surface 120a on the front side of the second conductive element 120.

[0081] At the in Fig. In the construction shown in Figure 9A, the distance b1 between the center of the second recess 122d2 and the center of the third recess 122d3 is greater than 1.15λ0 / 4. More preferably, the distance b1 is equal to or greater than 1.5λ0 / 4. Let a be the distance between the centers of two adjacent slots 112 along the Y-direction. The distance a can, for example, be designed to be approximately equal to the wavelength λg of an electromagnetic wave propagating in the waveguide. The wavelength λg is a wavelength that is determined by providing the additional elements compared to the wavelength λ R has varied. Although it may depend on the design, λg, for example, can be shorter than λ. R be. In this case, a < λ R , and therefore the distance (> λ R / 4) between the centers of the two adjacent recesses 122d2 and 122d3 longer than a / 4. In the construction from Fig. 9A the distance between the centers of the first recess 122d1 and the second recess 122d2 can be equal to or less than 1.15λo / 4.

[0082] In the construction from Fig. 9A Each recess functions as an element for locally increasing the inductance of the transmission line. Although the bottom of each recess and every other point besides the recesses are shown as flat, they may not actually be flat.

[0083] In the construction from Fig. 9A shows that the first recess 122d1 and the second recess 122d2 are provided on one rib, while the third recess 122d3 is provided on another rib. Without being limited to such an implementation, for example, the first to third recesses could be provided on one rib, or they could each be provided on three different ribs.

[0084] Fig. Figure 9B is a cross-sectional view showing a slotted antenna device according to yet another embodiment. In this example, a plurality of protrusions are provided on the waveguide element 122. The positions of the protrusions are selected such that the signal wave phase is varied at the positions of the plurality of slots 112, thus achieving characteristics suitable for a given purpose. As shown in the figure, the number, shapes, and sizes of the protrusions, as well as their positions on the rib, can differ from rib to rib.

[0085] In the construction from Fig. 9B features a multitude of protrusions on the waveguide element 122, comprising a first protrusion 122b1, a second protrusion 122b2, and a third protrusion 122b3, which are adjacent to each other and follow one another along the Y-direction (first direction). The distance between the centers of the first protrusion 122b1 and the second protrusion 122b2 differs from the distance between the centers of the second protrusion 122b2 and the third protrusion 122b3. Thus, in the Fig. In the construction shown in Figure 9B, at least within the depicted region, the spacing between the second conductive surface 110a and the waveguide surface 122a varies aperiodically along the Y-direction. The first to third protrusions mentioned above can be located at any position, as long as they are provided between the two outermost slots of the plurality of slots 112. The plurality of protrusions can be provided on the third conductive surface 120a.

[0086] At the in Fig. In the construction shown in 9B, the distance b2 between the center of the first elevation 122b1 and the center of the second elevation 122b2 is greater than 1.15λ0 / 4. More preferably, the distance b2 is 1.5λ0 / 4 or greater. If λg is shorter than λ R is, is a<λ R ; therefore, the distance (>λ R / 4) between the midpoints of the two adjacent elevations 122b1 and 122b2 longer than a / 4. In the case of the Fig. In the construction shown in 9B, the distance between the centers of the second elevation 122b2 and the third elevation 122b3 can be equal to or less than 1.15λo / 4.

[0087] During the construction from Fig. 9B states that each protrusion functions as an element for locally increasing the capacity of the transmission line. Although the top of each protrusion and every other point besides the protrusions are shown as flat, they may not actually be flat.

[0088] During the construction from Fig. In 9B, the second elevation 122d2 and the third elevation 122b3 are provided on one rib, while the first elevation 122b1 is provided on a different rib. Without being limited to such an implementation, for example, the first to third elevations could be provided on one rib, or they could each be provided on three different ribs.

[0089] Aperiodic constructions similar to those in Fig. 9A and Fig. 9B can also be realized by providing wide or narrow sections instead of recesses or protrusions. As an example, consider a case in which the waveguide element 122 has a plurality of wide sections on the waveguide surface 122a, wherein the plurality of wide sections increases the width of the waveguide surface 122a relative to each adjacent location. In this case, the plurality of wide sections includes a first wide section, a second wide section, and a third wide section, which are adjacent to each other and sequential along the Y-direction, and they can be arranged such that the distance between the centers of the first wide section and the second wide section differs from the distance between the centers of the second wide section and the third wide section.Consider also a case in which the waveguide element 122 has a plurality of narrow sections that narrow the width of the waveguide surface 122a relative to any adjacent location on the waveguide surface 122a. In this case, the plurality of narrow sections includes a first narrow section, a second narrow section, and a third narrow section, which are adjacent to each other and sequential along the Y-direction, and they can be arranged such that the distance between the centers of the first narrow section and the second narrow section differs from the distance between the centers of the second narrow section and the third narrow section. The first to third wide sections (or the first to third narrow sections) can be located at any position as long as they are provided between the two outermost slots of the plurality of slots 112.

[0090] During the construction from Fig. 9A and Fig. 9B The waveguide, located between the third conducting surface 120a and the waveguide surface 122a, has a plurality of positions at which the waveguide's inductance (or capacitance) exhibits local maxima or minima. This plurality of positions includes a first, second, and third position, which are adjacent to each other and sequential along the Y-direction. The distance between the centers of the first and second positions differs from the distance between the centers of the second and third positions. Thus, within a region containing a plurality of slots, a structure in which aperiodic variations in inductance or capacitance are introduced, at least locally, allows the phase of an electromagnetic wave propagating in the waveguide to be adjusted according to the desired properties.The first to third positions mentioned above can be located in any position, as long as they are between the two outermost slots.

[0091] Fig. Figure 9C is a cross-sectional view schematically illustrating the structure of a slot array antenna according to a further embodiment of the present disclosure. Viewed from a direction perpendicular to the waveguide surface 122a, this slot array antenna has a protrusion 122b at each midpoint between two adjacent slots 112. The protrusions 122b can also be located in other positions, without being limited to the positions shown in the figure. In such a design, each protrusion 122b functions as an element for locally increasing the capacitance of the transmission line. Again in this example, the top surface of each protrusion 122b, and any other location therein, is flat. The distance b between the midpoints of two adjacent protrusions 122b along the Y-direction satisfies b > 1.15λ0 / 4. More preferably, the distance b satisfies b > 1.5λ0 / 8.Similar properties can also be achieved with a design in which, instead of the protrusions 122b, wide sections are provided, or protrusions are provided on the third conductive surface 120a instead of on the waveguide surface 122a.

[0092] In the construction from Fig. 9C, the distance between the third conducting surface 120a and the waveguide surface 122a varies periodically along the Y-direction. However, the period of variation is longer than 1.15λ⁴ or λ R / 4. The period is equal to the distance (the slot interval) between the centers of two adjacent slots 112. When such a periodic construction is used, the period can be set to a value equal to or greater than 1 / 2 the slot interval. In other words, at least either the spacing between the third conducting surface 120a and the waveguide area 122a or the width of the waveguide area 122a can vary along the Y-direction with a period equal to or greater than 1 / 2 the distance between the centers of two adjacent slots 112. Alternatively, at least either the inductance or the capacitance of the waveguide extending between the third conducting surface 120a and the waveguide area 122a can vary along the Y-direction with a period equal to or greater than 1 / 2 the distance between the centers of two adjacent slots 112.

[0093] Fig. Figure 9D is a cross-sectional view schematically showing the structure of a slotted array antenna according to yet another embodiment of the present disclosure. In this slotted array antenna, a plurality of recesses are provided on the third conductive surface 120a of the first conductive element 110. The positions of the plurality of recesses along the Y-direction are identical to the positions of the plurality of recesses along the Y-direction in Figure 9D. Fig. 9A. The waveguide surface 122a of the waveguide element 122 has no protrusions or recesses and is flat.

[0094] Fig. Figure 9E is a cross-sectional view schematically showing the structure of a slotted array antenna according to yet another embodiment of the present disclosure. In this slotted array antenna, the third conductive surface 120a and the waveguide surface 122a each have both recesses and protrusions.

[0095] As in Fig. 9D and Fig. As shown in Figure 9E, the third conductive surface 120a of the second conductive element 120 can have at least either the protrusions or the recesses. In this case, with regard to manufacturing, the width of each recess or protrusion along the X-direction, i.e., the direction orthogonal to the direction in which the waveguide element 122 extends, is preferably wider than the width of the waveguide element 122, since this reduces the accuracy of the alignment along the X-direction required between the recesses or protrusions on the second conductive element 120 and the waveguide element 122. However, without limitation, the width of each recess or protrusion on the second conductive element 120 along the X-direction can be equal to or narrower than the width of the waveguide surface 122a of the waveguide element 122.

[0096] For slotted array antennas according to the in Fig. In the embodiments shown in Figures 9A to 9E, a waveguide formed by the third conductive surface 120a and the waveguide surface 122a has: at least one minimum position at which at least either the inductance or the capacitance of the waveguide has a local minimum; and at least one maximum position at which at least either the inductance or the capacitance of the waveguide has a local maximum. A “minimal position” is a position in the vicinity of a position along the Y-direction at which a function with respect to coordinates along the Y-direction, indicating the inductance or capacitance of the waveguide (or transmission line), assumes a local minimum value. Conversely, a “maximum position” is a position in the vicinity of a position along the Y-direction at which the aforementioned function assumes a local maximum value. If, as in the embodiments shown in Figures 9A to 9E, the inductance or capacitance of the waveguide has a local maximum value, the waveguide has a local minimum value. Fig. In the examples shown in 9A to 9E, where a local maximum or minimum of the inductance or capacitance is due to a recess with a flat bottom or a protrusion with a flat top, the central section of the recess or protrusion is considered the "maximum position" or "minimum position". In the examples shown in Fig. In the example constructions shown in 9A to 9D, the center of each recess is a "maximum position" where the inductance reaches a local maximum, and the center of the section between two adjacent recesses is a "minimal position" where the inductance reaches a local minimum. In contrast, in the Fig. 9B and Fig. In the example constructions shown in 9C, the center of each recess is a "maximum position" where the capacity reaches a local maximum, and the center of the section between two adjacent recesses is a "minimum position" where the capacity reaches a local minimum. Similarly, in the Fig. The example shown in 9E shows a variety of maximum positions and a variety of minimum positions.

[0097] Fig. Figure 9F is a cross-sectional view showing an embodiment in which a plurality of protrusions or recesses are arranged on the waveguide surface of the waveguide element 122. In this slotted array antenna, a plurality of very small recesses or protrusions are arranged periodically in an array-like manner on the rib 122. The period of this array is less than λ. R / 4, where λ RThe wavelength of a signal wave in a waveguide without any recesses or protrusions. Since the wavelength λ R Since the wavelength λ₀ in free space is less than 1.15 times the wavelength λ₀, the period of the array of recesses 122d is less than 1.15λ₀ / 4. Therefore, in the Fig. In the construction shown in Figure 9F, the distance b between the center of a recess and the center of an adjacent elevation along the Y-direction is shorter than 1.15λo / 8.

[0098] With reference to Fig. 10 and Fig. 11 will now be in Fig. 9C shown construction and the one in Fig. 9F compared to the construction shown.

[0099] Fig. Figure 10 is a graph showing the dependence of the waveguide's capacitance in the Fig. The construction shown in Figure 9C schematically illustrates the Y-direction. Fig. Figure 11 is a graph showing the dependence of the waveguide's capacitance in the Fig. The construction shown in Figure 9F schematically illustrates the Y-direction. These graphs demonstrate a change in capacity in a range from Y=0 to a, where the origin of the Y-coordinates is defined at the position of slot 112. It is noted that Fig. 10 and Fig. Figure 11 illustrates tendencies of capacity change along the Y-direction rather than being exact. As in Fig. 10 and Fig. As shown in 11, the construction changes both from Fig. 9C as well as in the construction from Fig. 9F represents the capacitance along the Y-direction, but with different periods. In the construction from Fig. 9C exhibits a local maximum in the vicinity of a protrusion 122b, after having exhibited a local minimum near a slot. The minimum position, which exhibits a local minimum, and the maximum position, which is adjacent to it along the Y-direction and exhibits a local maximum, are separated by approximately 1 / 2 of the slot interval a. In contrast, the construction from Fig. 9F with a fine period smaller than 1 / 4 of the wavelength λ R an electromagnetic wave on a ribbed waveguide without the recesses or protrusions.

[0100] If the slot array is designed such that electromagnetic waves with identical phase are emitted from the respective slots, the interval between adjacent slots along the Y-direction is essentially equal to the wavelength λg of a transmitted wave on the transmission line. Therefore, in this case, the design consists of Fig. 9C the capacitance varies with a long period, which is approximately equal to the wavelength λg, while in the construction from Fig. 9F the capacitance oscillates with a short period, which is less than 1 / 4 of the wavelength λ R is. In a short modulation structure that is smaller than 1 / 4 of the wavelength λ RIf the wavelength is measured, a transmitted wave is hardly reflected by each individual modulation, and the transmitted wave behaves as if propagating in a nearly uniform medium. In contrast, a transmitted wave in a long modulation structure equal to or greater than 1 / 4 of the wavelength λ can R The measurement is reflected by each individual modulation.

[0101] Although in the description of the constructions from Fig. In sections 9A to 9F, the term "wavelength" is used for practical purposes only. When the capacitance or inductance is varied over long intervals, a transmitted wave is subject to complex reflections, and the wavelength of an actual transmitted wave still needs to be directly verified. However, by imparting long-period variations to the capacitance or inductance, the excitation state of each slot in a WRG-based slot antenna can be appropriately adjusted to achieve the desired antenna characteristics. In such a state, the wavelength λg of a transmitted wave is assumed to be essentially equal to the interval between two adjacent slots 112. In the following description, it is assumed that even with a long-period variation of the capacitance or inductance, a wavelength λg can still be adaptively defined for any given situation.

[0102] As described above, changes occur in the Fig. In embodiments 9A to 9E, at least either the inductance or the capacitance between two adjacent slots in one direction along the waveguide element is based on a modulation structure longer than 1 / 4 of the wavelength λ. R How such a change actually occurs can be modified at will by adjusting the positions of additional elements such as raised sections, recesses, wide sections, and narrow sections. In contrast, the process varies in the Fig. In the embodiment shown in 9F, at least either the inductance or the capacitance is located between two adjacent slots along a direction corresponding to the waveguide element, based on modulation structures that are shorter than 1 / 4 of the wavelength λ. Rare. Similar to the periodic structures disclosed in patent document 1, these structures provide the effect of uniformly shortening the wavelength of a signal wave in the waveguide. Unlike the ones in Fig. In the constructions shown in 9A to 9E, the signal wave phase at the position of each slot 112 is not finely adjustable; in applications that do not require such fine adjustments, the Fig. The construction shown in 9F is applicable.

[0103] Fig. Figure 12 is a cross-sectional view showing another embodiment of the present disclosure. As in Fig. As illustrated in Figure 12, a construction can also be used in which a smooth variation in the height of the waveguide surface 122a of the rib 122 from the second conductive surface 110a is permitted. Such a construction also provides effects similar to those achieved by the construction from Fig. 9C. Similar effects can also be achieved by ensuring that the waveguide surface has a smoothly varying width. Thus, embodiments of the present disclosure can include a design with a smoothly varying distance between the third conductive surface 120a of the second conductive element 120 and the waveguide surface 122a of the waveguide element 122, and also a design in which the waveguide surface 122a has a smoothly varying width. Embodiments of the present disclosure are not limited to designs in which additional elements are clearly defined (e.g., a design in which protrusions or recesses are arranged in an array).

[0104] Raised features that serve to narrow the spacing between the third conductive surface 120a of the second conductive element 120 and the waveguide area 122a of the waveguide element 122 relative to any adjacent location, and wide sections that serve to widen the width of the waveguide area 122a relative to any adjacent location, may be referred to in this specification as "first-type add-on elements". A first-type add-on element has the function of increasing the capacitance of the transmission line. Furthermore, recesses that serve to widen the spacing between the third conductive surface 120a of the second conductive element 120 and the waveguide area 122a relative to any adjacent location, and narrow sections that serve to narrow the width of the waveguide area 122a relative to any adjacent location, may be referred to as "second-type add-on elements".An additional element of the second type serves to increase the inductance of the transmission line. In one implementation, the additional elements comprise one or more additional elements of the first type and / or one or more additional elements of the second type. An additional element of the first type may be adjacent to an additional element of the second type or to a location where no additional element is provided (also referred to in this specification as a "neutral section"). Likewise, an additional element of the second type may be adjacent to an additional element of the first type or to a neutral section. The distance between the centers of two such adjacent elements may, for example, be set to a value greater than 1 / 8 of the wavelength λ. Rwithin the waveguide, or to a value longer than 1.15 / 8 of the central wavelength λo in free space. More preferably, the distance between the centers of two adjacent elements can be set to a value equal to or greater than 1.5 / 8 of λo.

[0105] In one embodiment of the present disclosure, a special structure that can be considered a protrusion and thus a narrow section, or a special structure that can be considered a recess and thus a wide section, may be used as an additional element. A structure that is a protrusion which narrows the distance between the conductive surface and the waveguide area relative to an adjacent location, and which is a narrow section that narrows the width of the waveguide area relative to an adjacent location, may be referred to in the present specification as a "third-type additional element".Furthermore, a structure that is a recess widening the spacing between the conducting surface and the waveguide area relative to any adjacent location, and which is a wide section widening the width of the waveguide area relative to any adjacent location, can be referred to as a "fourth-type add-on element." Depending on their structure, a third-type add-on element and a fourth-type add-on element can each function as a capacitance component or an inductance component. The add-on elements can, as such, include one or more third-type add-on elements and / or one or more fourth-type add-on elements. A third-type add-on element can be adjacent to a fourth-type add-on element or to a neutral section where no add-on element is provided.Similarly, an additional element of a fourth type can be adjacent to an additional element of a third type or a neutral section. The distance between the centers of two such adjacent elements can, for example, be set to a value greater than 1 / 8 of λ. R is, or to a value longer than 1.15 / 8 of λo. More preferably, this distance between the centers can be equal to or greater than 1.5 / 8 of λo.

[0106] An embodiment of the present disclosure may also locally have any structure with a period smaller than 1 / 4 of the wavelength λ. R in a waveguide without protrusions or recesses, etc. Fig. Figure 13A is a cross-sectional view that schematically shows an example of such constructions. In this example, the waveguide element 122 has a plurality of very small recesses 122d. Each recess 122d has a dimension along the Y-direction that is smaller than λ. R / 8. The plurality of recesses 122d is provided at positions near the opposite ends of each rib, but not in the central section. The period of the plurality of recesses 122d at the opposite ends of each rib is less than λ. R / 4.

[0107] Fig. Figure 13B is a cross-sectional view that schematically shows yet another embodiment of the present disclosure. In this example, the waveguide element 122 has a plurality of very small protrusions 122b. The size of each protrusion along the Y-direction is less than λ. R / 8. On each rib of the waveguide element 122, the density of the protrusions 122b is higher near the central section and decreases towards the opposite ends. According to this example, variations in the average inductance or capacitance can arise based on how dense or sparse the very small accessory elements are (i.e., differences in density). In such an implementation, the “maximum position” and “minimum position” each refer to a region of some extent containing a multitude of very small accessory elements.

[0108] In the Fig. 13A and Fig. In the examples shown in Figure 13B, the very small recesses 122d and the very small elevations 122b are arranged in intervals that are locally shorter than λ. R / 4 or 1.15λo / 4. However, with respect to each repetition unit consisting of elevations and depressions, the repetition period is longer than λ. R / 4 or 1.15λo / 4. In other words, a modulation with a period longer than λ R / 4 or 1.15λo / 4 is placed over the intervals between the very small recesses 122d and the very small elevations 122b.

[0109] Fig. Figure 13C is a cross-sectional view schematically showing yet another embodiment of the present disclosure. In this embodiment, the waveguide element 122 has protrusions of two types with different heights. The protrusions of the two types alternate at equal intervals. The spacing between the waveguide surface 122a of the waveguide element 122 and the third conductive surface 120a of the second conductive element 120 is periodically varied along the Y-direction. In other words, the inductance and / or capacitance of the waveguide is periodically varied along the Y-direction. The period of this variation is shorter than half the slot interval. In this example, three types of positions with mutually varying spacing between the conductive surface 120a and the waveguide surface 122a occur such that they are adjacent along the Y-direction.Thus, the waveguide element 122 can be structured such that a multitude of protrusions with different heights are provided on it. By appropriately adjusting the heights of the protrusions according to the desired properties, it becomes possible to adjust the phase of an electromagnetic wave propagating in the waveguide and the excitation state of each slot 112. Without being limited to a multitude of protrusions with different heights, similar adjustments can also be made by providing a multitude of recesses with different depths or a multitude of wide sections or narrow sections with different widths. Instead of on the waveguide element 122, a multitude of protrusions or a multitude of recesses can be provided on the second conductive element 120.Between the two outermost slots of the plurality of slots 112, the spacing between the third conductive surface 120a and the waveguide surface 122a or the width of the waveguide surface 122a can vary in four or more steps.

[0110] Fig. Figure 13D is a diagram showing an example construction where the spacing (of the gap) between the conductive surface 120a and the waveguide surface 122a is varied at more positions than in the example from Fig. 13C, so that the gap varies over a shorter distance. In this example, there are six types of positions with mutually varying spacing between the conducting surface 120a and the waveguide surface 122a. Although the gap varies over a distance shorter than λ R / 4 or 1.15λo / 4, with reference to each repeat unit consisting of elevations and exclusions, the repeat period is longer than λ R / 4 or 1.15λ o / 4.

[0111] According to the in Fig. 13C and Fig. In the examples shown in Figure 13D, the waveguide existing between the conductive element 120 and the waveguide element 122 can have at least three types of locations with mutually varying spacing between the conductive surface 120a and the waveguide surface 122a. Likewise, the waveguide element 122 can have at least three types of locations with mutually varying widths of the waveguide surface 122a. It is not necessary that all of the at least three locations be situated between any two adjacent slots along the Y-direction from the plurality of slots 112; rather, it suffices if the at least three locations are situated between the two outermost slots. In these implementations, the spacing between the conductive surface 120a and the waveguide surface 122a, or the width of the waveguide surface 122a, can vary either periodically or aperiodically along the waveguide surface 122a.If it varies periodically, its period can be equal to or less than λ. R / 4 or 1.15λo / 4, as described above, or greater than these values.

[0112] Fig. Figure 14A is a diagram showing yet another structure for the waveguide component 122. Fig. Figure 14A is a top view showing an example arrangement of the first conductive element 110, the waveguide element 122, and the plurality of rods 124. Instead of varying the distance between the conductive surface 120a of the second conductive element 120 and the waveguide area 122a, the width of the waveguide area 122a is varied in this example. In such a design, the capacitance near the midpoint between two adjacent slots 112 along the Y-direction (in which the waveguide element 122 extends) is also increased, thus producing effects similar to those achieved, for example, in Fig. The construction shown in Figure 9C is achieved. Although in this example wide sections 122e are used instead of the aforementioned protrusions, narrow sections can also be used instead of the aforementioned recesses. Furthermore, structures exhibiting variations in both height and width compared to the sections without additional elements (i.e., neutral sections) can also be used as additional elements. Additionally, instead of protrusions, recesses, wide sections, or narrow sections, sections with a dielectric constant different from that of the surroundings can also be provided as additional elements at suitable positions between the conducting surface 110a and the waveguide surface 122a.

[0113] Fig. Figure 14B is a diagram showing yet another structure for the waveguide component 122. This figure is in the same way as Fig. 14A drawn. During Fig. Figure 14A illustrates an example where the wide sections 122e are arranged at equal intervals along the Y-direction in which the waveguide element 122 extends. In this example, the wide sections 122e are not arranged at equal intervals. The interval between the first wide section 122e and the second wide section 122e, in Fig. The interval between the second wide section 122e and the third wide section 122e, counted in the Y-direction from the top, is larger than the interval between the second wide section 122e and the third wide section 122e. Furthermore, the waveguide element 122 also has narrow sections 122f. The fourth wide section 122e is followed by four narrow sections 122f. In these narrow sections, the interval between the first narrow section 122f and the second narrow section 122f, counted in the Y-direction from the top, is smaller than the interval between the second narrow section 122f and the third narrow section 122f.

[0114] By locally varying the intervals between wide sections or narrow sections (i.e., sections with reduced width), or by providing both wide and narrow sections, the slot array antenna can be given the required properties in this way.

[0115] Additional elements according to one embodiment of the present disclosure can be considered as elements that, like concentrated parameter elements, are locally added to a distributed constant circuit having a specific characteristic impedance. The placement of such additional elements at suitable positions allows for flexible adjustments tailored to the application or purpose. For example, the gain can be maximized by: adjusting the wavelength of a signal wave within the waveguide to a desired length and applying standing wave series feeding or traveling wave feeding to produce an excitation with the same amplitude and phase.Alternatively, a directional characteristic can be set by intentionally introducing a desired phase difference between the slots, or electromagnetic waves of a desired intensity can be emitted from a multitude of slots by applying traveling wave feed. Thus, the technique of the present disclosure is applicable to a wide variety of purposes or applications.

[0116] Next, more specific example designs for waveguide devices according to embodiments of the present disclosure are described. It should be noted, however, that unnecessarily detailed descriptions may have been omitted. For example, detailed descriptions of technically known facts or redundant descriptions of essentially identical designs may have been omitted. This is to avoid excessively long descriptions and to facilitate understanding by those skilled in the art. The accompanying drawings and the following description, provided by the inventors to enable those skilled in the art to gain a sufficient understanding of the present disclosure, are not intended to limit the scope of the claims. In this specification, identical or similar components are designated by identical reference numerals. <Ausführungsform 1>

[0117] Fig. Figure 15A is a top view schematically showing a partial construction of a slotted antenna device 300 (hereinafter also referred to simply as "antenna device 300") according to a first embodiment of the present disclosure. Fig. Figure 15B is a perspective view that more specifically shows the structure of a first conductive element 110 of the antenna device 300 and a waveguide element 122 thereon. Fig. 15B shows a variety of conductive bars 124, except for some with faint colored lines. Fig. Figure 15C is a diagram that schematically shows a cross-sectional structure of the antenna device 300, taken from a cross-section passing through the centers of a plurality of slots 112 and parallel to the YZ plane.

[0118] The antenna device 300 of the present embodiment has a slotted antenna array structure, the radiating elements of which are a plurality of slots 112. The first conductive element 110 has the plurality of slots 112. The plurality of slots 112 is arranged in an array-like fashion along the Y-direction in which the waveguide element 122 extends. The plurality of slots 112 has four slots 112A, 112B, 112C and 112D.

[0119] The waveguide element 122 is divided into a plurality of sections (“ribs”) at the positions of the plurality of slots 112. In the present embodiment, the waveguide element 122 has five ribs 122Ch, 122A, 122B, 122C, and 122D, which lie on a straight line. Viewed from a direction perpendicular to the waveguide surface of the waveguide element 122, each slot 112 is arranged between the ends of two adjacent ribs from the plurality of ribs. Specifically, slot 112A is arranged between rib 122Ch and rib 122A. Slot 112B is arranged between rib 122A and rib 122B. Slot 112C is arranged between rib 122B and rib 122C. The slot 112D is located between the rib 122C and the rib 122D.

[0120] In the following description, slots 112A, 112B, 112C, and 112D may be referred to collectively as "slots 112" without distinction. Similarly, ribs 122Ch, 122A, 122B, 122C, and 122D may be referred to collectively as "ribs 122" without distinction. The same applies to any other component.

[0121] Adjacent to the outermost slot 112A of the plurality of slots 112, a choke structure 150 is provided. The choke structure can be formed, for example, from: an additional transmission line with a length of approximately λ0 / 8; and a row of several depressions with a depth of approximately λ0 / 4; or a row of several conductive bars 124 with a height of approximately λ0 / 4, arranged at one end of the additional transmission line. In the present embodiment, the choke structure 150 has the rib 122Ch and one or more conductive bars 124 arranged along the Y-direction close to the rib 122Ch. In this case, the additional transmission line corresponds to the waveguide extending between the rib 122Ch and the third conductive surface 120a. In the following description, the rib contained in the choke structure 150 is referred to as the "choke rib".

[0122] The choke structure 150 imparts a phase difference of approximately 180°(π) between an incident wave and a reflected wave, thereby limiting electromagnetic leakage at the end of the waveguide element 122. Instead of being located on the first conductive element 110, such a choke structure 150 can be provided on the second conductive element 120.

[0123] It was conventionally assumed that the length of the additional transmission line of a choke structure should be λr / 4, where λr is the wavelength of a signal wave on the transmission line. However, the inventors found that even when the length of the additional transmission line of the choke structure is shorter than λr / 4, electromagnetic leakage can still be suppressed, and improved functionality can be achieved compared to λr / 4. In fact, the length of the additional transmission line is preferably λ0 / 4 or less, i.e., shorter than λr / 4. In the present embodiment, the length of the additional transmission line, i.e., the length of the choke rib 122Ch along the Y-direction, is set, for example, equal to or greater than λ0 / 16 and less than λ0 / 4.

[0124] The conducting bars 124 contained in the choke structure 150 may have a different shape than the conducting bars 124 contained in the artificial magnetic conductor extending on both sides of the waveguide element 122. The choke rib 122Ch may have the same shape as the conducting bar 124.

[0125] In the present embodiment, the artificial magnetic conductor extending on both sides of the waveguide element 122 comprises a row of conductive bars 124 adjacent to the waveguide element 122 in the +X direction and a row of conductive bars 124 adjacent to the waveguide element 122 in the -X direction. In each such row of conductive bars 124, the plurality of conductive bars 124 are arranged along the Y direction. The artificial magnetic conductor on one side of the waveguide element 122 can comprise two or more rows of conductive bars 124. As will be described later, a single row of conductive bars 124 is also to be considered an artificial magnetic conductor in the present disclosure.

[0126] The waveguide element 122 has a plurality of recesses 122d on the waveguide surface. Each of the three ribs 122A, 122B, and 122C has two recesses 122d, each arranged between the central section of the rib on the waveguide surface and the opposite ends. The recesses 122d adjust the relative phase differences between the signal waves at the positions of the slots 112 in a suitable manner, thereby achieving desired radiation or reception characteristics.

[0127] As in Fig. As shown in Figure 15C, the waveguide extending between the waveguide element 122 and the second conductive element 120 is connected to a transmitter or receiver either directly or via another waveguide. The other waveguide may, for example, be another finned waveguide (not shown), a hollow waveguide, or a microstrip line. The transmitter or receiver may be located in a different layer than the layer in which the waveguide element 122 is located. Fig. The waveguide shown in Figure 15C is formed. In this case, a waveguide must be used that connects between such layers.

[0128] The transmitter is a device or circuit that supplies power to the waveguide in the antenna device 300 and causes a signal wave to be emitted from each slot 112. The receiver is a device or circuit that receives a signal wave that has struck the respective slot 112 of the antenna device 300 and propagated through the waveguide. The transmitter and the receiver can each be implemented, for example, as an integrated millimeter-wave circuit. The antenna device 300 can be connected to a device that functions as both a transmitter and a receiver.

[0129] During transmission, a signal wave supplied from the transmitter propagates through the waveguide extending between the waveguide element 122 and the second conductive element 120, exciting the plurality of slots 112. As a result, signal waves are emitted. Conversely, during reception, signal waves arriving at the plurality of slots 112 propagate through the waveguide extending between the waveguide element 122 and the second conductive element 120 and arrive at the receiver. As a result, signal waves are received.

[0130] The intervals between the multitude of slots 112 are, for example, set approximately equal to the wavelength of a signal wave propagating in the waveguide. In this case, signal waves with the same phase are emitted from the respective slots 112. For other purposes, e.g., to reduce side lobes, etc., the intervals between the slots 112 can differ from the wavelength of a signal wave in the waveguide.

[0131] Fig. Figure 15D is a perspective view showing two adjacent beam elements from the plurality of beam elements in the present embodiment. Fig. In 15D, the multiple conductive rods 124 and the second conductive component 120 are omitted from the illustration.

[0132] According to the present embodiment, a cross-section of each slot 112, perpendicular to its central axis, has an H-shape. The central axis of a slot 112 is defined as an axis that passes through the center of the slot 112 and is perpendicular to the opening plane of the slot 112. The term "H-shape" refers to a shape that, like the letter "H", has two vertical sections that are substantially parallel to each other and a lateral section that connects the central sections of the two vertical sections. The use of an H-shaped slot 112 allows for advantages over the one described in Fig. The shape of slot 112 shown in Figure 7A represents a reduction in width along a direction perpendicular to the E-plane. It is noted that the E-plane is a plane containing electric field vectors to be generated in the central section of slot 112. In the examples from Fig. 7A and Fig. 15A is parallel to the E-plane and the YZ-plane.

[0133] The above construction provides a slotted antenna device for transmitting or receiving purposes, whose radiating elements are the plurality of slots 112. Since a waveguide structure is used, as in a comparative example, a low-loss antenna is achievable even in the high-frequency range, compared to an antenna using microstrip lines. Furthermore, according to the present embodiment, the plurality of recesses 122d in the waveguide surface of the waveguide element 122 appropriately sets the excitation state of each slot. <Ausführungsform 2>

[0134] Next, a second embodiment of the present disclosure will be described.

[0135] Fig. Figure 16A is a top view showing a partial assembly of a slotted antenna device 300 according to the present embodiment. One difference between the present embodiment and embodiment 1 is that the shape of the opening of each slot 112 is an I-shape. An "I-shape" is a shape that extends in a straight line, like the letter "I". Otherwise, the present embodiment is similar to embodiment 1.

[0136] Fig. Figure 16B is a perspective view showing two of the four beam elements. Fig. In Figure 16B, the multitude of conducting rods 124 is omitted from the illustration. Even when I-shaped slots 112 are used as beaming elements, an efficient slotted antenna can be realized, similar to embodiment 1.

[0137] The first conductive surface 110b of the first conductive element 110 can have a shape that defines at least one horn communicating with at least one slot 112. By providing one or more such horns, the degree of impedance matching is increased, thereby suppressing signal wave reflection.

[0138] Fig. Figure 17 is a perspective view showing two beam elements according to a variant of embodiment 2. Fig. In Figure 17, the plurality of conductive rods 124 and the second conductive element 120 are omitted from the illustration. In this variant, the first conductive surface 110b of the first conductive element 110 on the front side has a shape that defines a plurality of horns 114, each of which communicates with the plurality of slots 112. In this example, each plurality of slots 112 is open to the outside space via the plurality of horns 114. By providing such horns 114, the characteristic impedance within each slot can be gradually brought closer to the characteristic impedance in free space, thereby achieving an improved radiation efficiency.

[0139] Fig. Figure 18A is a perspective view showing a beam element according to a further variant of embodiment 2. The slot antenna device from this example further comprises another conductive component 160 with a conductive surface that is opposite the conductive surface 110b on the front face of the first conductive component 110. In this example, the further conductive component 160 has four additional slots 111. Fig. 18B is a diagram showing the beam element from Fig. Figure 18A shows an illustration in such a way that the spacing between the first conductive element 110 and the second conductive element 160 is exaggerated. The multitude of conductive rods 124 extending on both sides of the waveguide element 122, and the second conductive element 120 with a conductive surface facing opposite to the waveguide surface of the waveguide element 122, are shown in Fig. 18A and Fig. 18B is omitted from the illustration.

[0140] In Fig. In 17, the slots 112 are shown in such a way that they communicate with the horns 114; in the example from Fig. In contrast, in 18A, slot 112 communicates with a cavity 180. Cavity 180 is a shallow hollow space surrounded by the first conductive surface 110b, a plurality of conductive bars 170 on the front of the first conductive element 110, and the conductive surface on the back of the conductive element 160. In this example, slot 112 is open to the outer space via cavity 180. In the examples from Fig. 18A and Fig. 18B A gap exists between the leading ends of the multitude of conductive bars 170 and the conductive surface on the back side of the further conductive component 160. The roots of the multitude of conductive bars 170 are connected to the first conductive surface 110b of the first conductive component 110. A design can be used in which the multitude of conductive bars 170 is connected to the further conductive component 160. In this case, however, it is ensured that a gap exists between the leading ends of the multitude of conductive bars 170 and the first conductive surface 110b.

[0141] The additional conductive element 160 has four further slots 111, such that all slots 111 communicate with the cavity 180. A signal wave radiated from slot 112 into the cavity 180 is radiated via the four further slots 111 towards the front face of the additional conductive element 160. It is noted that a structure can be used in which horns are arranged on the front face of the additional conductive element 160, with the further slots 111 opening on the undersides of the horns. In this case, a signal wave radiated from slot 112 is radiated via the cavity 180, the further slots 111, and the horns.

[0142] Horns like the ones in Fig. The 17 shown can be provided for the slotted antenna device 300 with H-shaped slots 112 from embodiment 1. For example, a construction as shown in Fig. 19 and Fig. 20 shown. Fig. Figure 19 is a diagram showing a rear view of a first conductive element 110 of a slotted antenna device 300, in which a plurality of horns 114 are each provided around a plurality of H-shaped slots 112. Fig. 19 The horns 114, which are actually located behind the plane of the figure, are also illustrated to make it easier to understand their respective positioning. Fig. 20 is a cross-sectional view along line AA in Fig. 19. In this example as well, the provision of the horns 114 enables the suppression of a reflection when passing through the slots 112. <Ausführungsform 3>

[0143] Next, a third embodiment of the present disclosure is described. An antenna device 300 according to the present embodiment has at least three stacked conductive elements. The transmitter or receiver is arranged in a layer that is positioned further towards the rear than the second conductive element 120.

[0144] Fig. Figure 21A is a cross-sectional view schematically illustrating the construction of the antenna device 300 of the present embodiment. In addition to a first conductive element 110 and a second conductive element 120, the antenna device 300 has a third conductive element 140. Furthermore, in addition to a first waveguide element 122U connected to the first conductive element 110, the antenna device 300 has a second waveguide element 122L. The second waveguide element 122L is arranged between the second conductive element 120 and the third conductive element 140.

[0145] The first conductive element 110 is structurally identical to the first conductive element 110 in embodiment 1 or embodiment 2. However, in the present embodiment, two choke structures 150U are provided near the two ends of the waveguide element 122U. The choke structures 150U restrict the propagation of signal waves, which are fed in branches from the central section of the line through four slots 112, beyond the two slots 112 at opposite ends.

[0146] The first waveguide element 122U has a plurality of recesses that are periodically arranged along the Y-direction on the waveguide surface 122La. These recesses shorten the wavelength within the waveguide, thereby reducing the intervals between the slots 112.

[0147] In addition to the third conductive surface 120a on the front side, the second conductive element 120 has a fourth conductive surface 120b on the rear side. The second conductive element 120 has a port 145 (through hole) extending from the third conductive surface 120a to the fourth conductive surface 120b. The port 145 is opposite to the central section of the waveguide surface 122Ua of the waveguide element 122U. In other words, viewed from a direction perpendicular to the first conductive surface 110b, the port 145 is located in the middle of the row of four slots 112.

[0148] The third conductive element 140 has a fifth conductive surface 140a on its front side, the fifth conductive surface 140a being opposite to the fourth conductive surface 120b. The rib-shaped second waveguide element 122L is provided on the fifth conductive surface 140a of the third conductive element 140.

[0149] The second waveguide element 122L extends in the Y-direction along the fourth conductive surface 120b. The second waveguide element 122L has an electrically conductive waveguide surface 122La that faces opposite the fourth conductive surface 120b. The waveguide surface 122La also faces opposite the port 145. Viewed from a direction perpendicular to the waveguide surface 122La, the second waveguide element 122L extends to a position slightly beyond the port 145.

[0150] An artificial magnetic conductor, not shown, extends on both sides of the second waveguide element 122L. The artificial magnetic conductor can be realized by a plurality of conductive bars arranged at least on either the fourth conductive surface 120b or the fifth conductive surface 140a. The fourth conductive surface 120b, the waveguide surface 122La, and the artificial magnetic conductor define a second waveguide in a space extending between the fourth conductive surface 120a and the waveguide surface 122La. Via port 145, the second waveguide is connected to a first waveguide extending between the waveguide surface 122Ua of the first waveguide element 122U and the third conductive surface 120a of the second conductive element 120.The second waveguide is connected to a transmitter or receiver either directly or via another waveguide (not shown).

[0151] A choke structure 150L is arranged at one end of the second waveguide element 122L. In a view obtained by projecting the opening of port 145 onto the waveguide surface 122La, a section spanning the area from the edge to one end of the waveguide element 122L is referred to as the waveguide element end. The choke structure 150L has one or more conductive bars 124L arranged on the fifth conductive surface 140a, with a gap between the waveguide element end and one end of the waveguide element 122L. The length of the waveguide element end along the Y-direction is approximately equal to the length of the choke rib 122Ch along the Y-direction. Such a choke structure 150L suppresses leakage of a signal wave propagating along the second waveguide element 122L.

[0152] In the present embodiment, a signal wave supplied from the transmitter during transmission propagates along the waveguide surface 122La of the second waveguide element 122L and passes through port 145 to branch in two directions. The branched signal waves propagate along the waveguide surface 122Ua of the first waveguide element 122U and excite the four slots 112. Viewed from a direction perpendicular to the waveguide surface 122Ua, the four slots 112 are located at symmetrical positions with respect to port 145. The distances between the centers of these slots 112 are shorter than the wavelength of a signal wave in free space. Therefore, the four slots 112 are excited with the same phase.Even with such a design, the multitude of recesses arranged on the waveguide surface 122Ua provided the effect of shortening the wavelength of a signal wave in the waveguide, thereby enabling the four slots 112 to be excited with the same phase. Of the four slots 112, the two slots 112 adjacent to port 145 are equidistant from port 145 and are therefore excited with the same phase, without the need for a multitude of recesses on the waveguide surface 122Ua. For other purposes, e.g., to reduce side lobes, etc., the multitude of slots 112 can be excited with different phases.

[0153] Next, variants of the present embodiment will be described.

[0154] Fig. Figure 21B is a cross-sectional view showing a first variant of the present embodiment. In this variant, the second waveguide element 122L and the plurality of conductive rods 124L are arranged on the fourth conductive surface 120b of the second conductive element 120 instead of on the fifth conductive surface 140a of the third conductive element 140. Therefore, the choke structure 150L is also provided on the fourth conductive surface 120b. The waveguide surface 122La of the second waveguide element 122L faces opposite the fifth conductive surface 140a. The second waveguide element 122L extends along the fifth conductive surface 140a.

[0155] An end face of the second waveguide element 122L is connected to the inner wall surface of port 145. Although the end face of the second waveguide element 122L and the inner wall surface of port 145 are not shown stepped, they can alternatively be stepped. Similar to the choke structures 150U on the first conductive element 110, the choke structure 150L has a choke rib 122Lch and one or more conductive bars 124L.

[0156] In this variant, the fifth conductive surface 140a, the waveguide surface 122La, and the artificial magnetic conductor extending on both sides of the waveguide element 122L define a second waveguide in a space extending between the fifth conductive surface 140a and the waveguide surface 122La. The second waveguide is connected via port 145 to a first waveguide extending between the waveguide surface 122Ua of the waveguide element 122U and the third conductive surface 120a. The second waveguide is connected to a transmitter or receiver, either directly or via another waveguide (not shown).

[0157] In the Fig. 21A and Fig. In the examples shown in Figure 21B, the first waveguide elements 110 have four slots 112 arranged along the Y-direction in which the waveguide element 122U extends. While not limited to four slots 112, five or more slots 112 are also possible. Furthermore, the slots 112 need not be located in symmetrical positions with respect to port 145. For example, three ports may be provided in the +Y-direction and two ports in the -Y-direction of port 145.

[0158] Fig. Figure 21C is a cross-sectional view showing another variant of the present embodiment. In this example, port 145 is located in the second conductive element 120 near one end of the waveguide element 122U. Therefore, a signal wave propagates from one end to the other end of the waveguide element 122U. In this way, power can be supplied from one end of the waveguide element 122U. In addition to the example from Fig. 21C can connect the second waveguide element 122L and the artificial magnetic conductor extending on both sides of it to the in Fig. The second conductive element 120 can be arranged as shown in 21B. Such a construction also provides similar properties.

[0159] Although in the above embodiment each conductive element has a single waveguide element, it can also have a plurality of waveguide elements.

[0160] In the Fig. In the embodiments illustrated in 21A to 21C, the recesses on the waveguide surface 122La are shown in a periodic arrangement. However, their arrangement need not be periodic; nor do they need to be recesses. Among the embodiments illustrated in Fig. The cutouts or raised sections shown in 9A to 9E can be selected according to purpose. The Fig. 12 or Fig. The recesses or protrusions shown in 13A to 13C may also be selected.

[0161] Fig. Figure 22 is a perspective view showing an example antenna device 300 with a plurality of waveguide elements 122. The antenna device 300 has a plurality of rib-shaped waveguide elements 122 on the second conductive surface 110a of the first conductive element 110. The first conductive element 110 has a plurality of slots 112. Each plurality of waveguide elements 122 has a plurality of ribs extending along a common path. Viewed from a direction perpendicular to the waveguide surfaces of the plurality of waveguide elements 122, each of the plurality of slots 112 is arranged between two adjacent of the plurality of ribs. Fig. Figure 22 illustrates an example where the slots 112 are located in a one-dimensional array; they can also form a two-dimensional array. The multitude of slots 112 can be supplied with an identical signal wave, which is branched along a feed path (not shown), or different signal waves can be supplied.

[0162] In embodiments 1 to 3, a plurality of recesses 122d are formed in the waveguide surface 122a of the waveguide element 122. Instead of such recesses 122d, narrow sections, which are smaller in width than at any adjacent point, or protrusions or wide sections can be provided. Such recesses or protrusions can be provided on the third conductive surface 120a of the second conductive element 120, which is opposite the waveguide surface 122a. By appropriately arranging these additional elements, the phase differences between signal waves at the positions of the slots 112 can be adjusted according to the purpose. (Other variants)

[0163] Next, with reference to Fig. 23 Example cross-sectional shapes of the port 145 or the slots 111, 112 are described in more detail below. In the following description, the port 145 and the slots 11, 112 may be referred to collectively as "through holes". Each port 145 or slot 111, 112 according to an embodiment of the present disclosure allows the following modifications.

[0164] In Fig. Figure 23 (a) shows an example of a through-hole 1400a with the shape of an ellipse. The major semi-axis La of the through-hole 1400a, indicated in the figure by arrowheads, is chosen such that no higher-order resonance occurs and that the impedance is not too low. More specifically, La can be adjusted such that λ0 / 4 < La < λ0 / 2, where λ0 is a wavelength in free space corresponding to the center frequency in the operating frequency band.

[0165] In Fig. Figure 23 (b) shows an example of an H-shaped through-hole 1400b, comprising a pair of vertical sections 113L and a lateral section 113T connecting the pair of vertical sections 113L. The lateral section 113T is substantially perpendicular to the pair of vertical sections 113L and connects substantially central sections of the pair of vertical sections 113L. The shape and size of such an H-shaped through-hole 1400b are also to be determined such that no higher-order resonance occurs and that the impedance is not too low. The distance between an intersection of the centerline g2 of the lateral section 113T and the centerline h2 of the entire H-shape, which is perpendicular to the lateral section 113T, and an intersection of the centerline g2 and the centerline k2 of a vertical section 113L is denoted by Lb.The distance between an intersection point of the centerline g2 and the centerline k2 and the end of the vertical section 113L is denoted by Wb. The sum of Lb and Wb is chosen such that λ0 / 4 < Lb + Wb < λ0 / 2. If the distance Wb is chosen to be relatively long, the distance Lb can be relatively short. Consequently, the width of the H-shape along the X-direction can be, for example, less than λ0 / 2, which allows the interval between the lateral sections 113T along the longitudinal direction to be short.

[0166] In Fig. Figure 23 (c) shows an example of a through-hole 1400c having a lateral section 113T and a pair of vertical sections 113L extending from both ends of the lateral section 113T. The directions in which the pair of vertical sections 113L extend from the lateral section 113T are substantially perpendicular to the lateral section 113T and are opposite to each other. The distance between an intersection of the centerline g3 of the lateral section 113T and the centerline h3 of the entire shape, perpendicular to the lateral section 113T, and an intersection of the centerline g3 and the centerline k3 of a vertical section 113L is denoted by Lc. The distance between an intersection of the centerline g3 and the centerline k3 and the end of the vertical section 113L is denoted by Wc. The sum of Lc and Wc is chosen such that λo / 4 < Lc + Wc < λo / 2 is satisfied.If the distance WC is chosen to be relatively long, the distance Lc can be relatively short. Consequently, the width along the X-direction of the entire shape in (c) can be . Fig. 23 e.g. smaller than λo / 2, which means that the interval between the lateral sections 113T along the longitudinal direction can be short.

[0167] In Fig. Figure 23 (d) shows an example of a through-hole 1400d having a lateral section 113T and a pair of vertical sections 113T extending from both ends of the lateral section 113T in an identical direction, perpendicular to the lateral section 113T. Such a shape may be referred to as a ‘U-shape’ in this specification. It is noted that the one shown in (d) is made of Fig. The shape shown in Figure 23 can be considered the upper half of an H-shape. The distance between an intersection point of the centerline g4 of the lateral section 113T and the centerline h4 of the entire shape, which is perpendicular to the lateral section 113T, and an intersection point of the centerline g4 and the centerline k4 of a vertical section 113L is denoted by Ld. The distance between an intersection point of the centerline g4 and the centerline k4 and the end of the vertical section 113L is denoted by Wd. The sum of Ld and Wd is chosen such that λ0 / 4 < Ld + Wd < λ0 / 2. If the distance Wd is chosen to be relatively long, the distance Ld can be relatively short. Consequently, the width along the X-direction of the U-shape can be, for example, less than λ0 / 2, which allows the interval between the lateral sections 113T to be short along the longitudinal direction.

[0168] Next, further variants for waveguide structures, including the conductive element 122, the conductive elements 110 and 120, and the plurality of conductive rods 124, are described. The following variants apply to the waveguide structure at every point in each embodiment described above.

[0169] Fig. Figure 24A is a cross-sectional view showing an example structure where only the waveguide surface 122a, which defines an upper surface of the waveguide element 122, is electrically conductive, while every other section of the waveguide element 122, apart from the waveguide surface 122a, is not electrically conductive. Similarly, both the conductive element 110 and the conductive element 120 are electrically conductive only on the surface where the waveguide element 122 is located (i.e., the conductive surface 110a, 120a), but not in any other section. Thus, not every part of the waveguide element 122, the conductive element 110, and the conductive element 120 needs to be electrically conductive.

[0170] Fig. Diagram 24B shows a variant where the waveguide element 122 is not formed on the conductive element 120. In this example, the waveguide element 122 is attached to a support element (e.g., the inner wall of the housing), which supports the conductive element 110 and the conductive element 120. A gap exists between the waveguide element 122 and the conductive element 120. Thus, the waveguide element 122 does not need to be connected to the conductive element 120.

[0171] Fig. Figure 24C is a diagram showing an example structure in which the conductive element 120, the waveguide element 122, and each of the plurality of conductive rods 124 are formed from a dielectric surface coated with an electrically conductive material such as a metal. The conductive element 120, the waveguide element 122, and the plurality of conductive rods 124 are interconnected via the electrical conductor. In contrast, the conductive element 110 is made of an electrically conductive material such as a metal.

[0172] Fig. 24D and Fig. Figure 24E are diagrams, each showing an example structure in which dielectric layers 110c and 120c are provided on the outermost surfaces of conductive components 110 and 120, a waveguide component 122 and conductive rods 124. Fig. Figure 24D shows an example structure in which the surface of conductive metal components, which are electrical conductors, is covered with a dielectric layer. Fig. Figure 24E shows an example in which the conductive component 120 is structured such that the surface of components formed from a dielectric, e.g., resin, is covered with a conductor such as a metal, wherein this metal layer is further coated with a dielectric layer. The dielectric layer covering the metal surface can be a coating of resin or the like, or an oxide film of a passivation coating or the like, which is produced by the oxidation of the metal.

[0173] The dielectric layer on the outermost surface allows for an increase in losses in the electromagnetic wave propagating through the WRG waveguide, but it protects the conductive surfaces 110a and 120a (which are electrically conductive) from corrosion. It also prevents the effects of a DC voltage or an AC voltage of such low frequency that it is incapable of propagating on certain WRG waveguides.

[0174] Fig. Figure 24F is a diagram showing an example where the height of the waveguide element 122 is lower than the height of the conducting rods 124, and the section of the conducting surface 110a of the conducting element 110, which faces away from the waveguide surface 122a, projects towards the waveguide element 122. Such a structure also functions similarly to the embodiment described above, as long as the Fig. The 4 illustrated dimensional ranges are adhered to.

[0175] Fig. 24G is a diagram showing an example where the structure continues to consist of Fig. 24F Sections of the conductive surface 110a, which are opposite to the conductive bars 124, project in the direction of the conductive bars 124. Such a structure also functions similarly to the embodiment described above, as long as the in Fig. The 4 dimension ranges shown are adhered to. Instead of a structure in which the conductive surface 110a partially protrudes, a structure in which the conductive surface 110a is partially recessed can be used.

[0176] Fig. Figure 25A is a diagram showing an example where a conductive surface 110a of the conductive component 110 is shaped as a curved surface. Fig. Figure 25B is a diagram showing an example where a conductive surface 120a of the conductive component 120 is also shaped as a curved surface. As these examples show, the conductive surfaces 110a, 120a may not be shaped as planes, but may also be shaped as curved surfaces. A conductive component with a conductive surface that is a curved surface is also considered a conductive component with a "plate shape".

[0177] In the waveguide device 100 with the construction described above, a signal wave at the operating frequency cannot propagate in the space between the surface 125 of the artificial magnetic conductor and the conductive surface 110a of the conductive element 110, but rather propagates in the space between the waveguide surface 122a of the waveguide element 122 and the conductive surface 110a of the conductive element 110. Unlike a hollow waveguide, the width of the waveguide element 122 in such a waveguide structure does not need to be equal to or greater than half the wavelength of the electromagnetic wave to be propagated. Furthermore, the conductive element 110 and the conductive element 120 do not need to be electrically connected to each other by a metal wall extending along the thickness direction (i.e., parallel to the YZ plane).

[0178] A slotted antenna device or slotted array antenna according to one embodiment of the present disclosure is suitable for use in a radar device or radar system for installation, for example, in moving objects such as vehicles, watercraft, aircraft, robots, or the like. A radar device would comprise a slotted array antenna according to one embodiment of the present disclosure and an integrated microwave circuit connected to the slotted array antenna. A radar system would comprise the radar device and a signal processing circuit connected to the integrated microwave circuit of the radar device.A slotted antenna device according to an embodiment of the present disclosure has a multi-layered waveguide structure that allows for a reduction in size and thus, compared to a design using a conventional hollow waveguide, a reduction in the area on which antenna elements are arranged in an array. Therefore, a radar system incorporating the antenna device can be easily mounted in a confined space, such as on a surface of a rearview mirror in a vehicle opposite its mirror surface, or in a small, moving object such as a UAV (an unmanned aerial vehicle, a so-called drone). It is noted that, without being limited to implementation in a vehicle, a radar system can be used, for example, fixed to a road or a building.

[0179] A slotted antenna device according to one embodiment of the present disclosure can also be used in a wireless communication system. Such a wireless communication system would comprise a slotted antenna device according to one of the above embodiments and a communication circuit (a transmitting circuit or a receiving circuit). Details of application examples for wireless communication systems will be described later.

[0180] A slotted antenna device according to an embodiment of the present disclosure can furthermore be used as an antenna in an indoor positioning system (IPS). An indoor positioning system is capable of identifying the position of a moving object, such as a person or an automated guided vehicle (AGV), located within a building. An antenna device can also be used as a radio wave transmitter (radio beacon) for a system that transmits information to an information terminal device (e.g., a smartphone) carried by a person who has visited a store or other establishment. In such a system, a radio beacon can emit an electromagnetic wave every few seconds, carrying, for example, an identifier or other information.When the information terminal receives this electromagnetic wave, it transmits the received information via telecommunications links to a remote server computer. Based on the information received from the information terminal, the server computer identifies the location of the information terminal and sends information associated with that location (e.g., product information or a voucher) to the information terminal.

[0181] In this specification, the term “artificial magnetic conductor” is used to describe the technology according to the present disclosure, in accordance with the description in a paper by one of the inventors, Kirino (non-patent document 1), and in a paper by Kildal et al., who published an investigation on a related subject at approximately the same time. However, an investigation by the inventors revealed that the invention according to the present disclosure does not necessarily require an “artificial magnetic conductor” according to the conventional definition. That is to say, while a periodic structure is currently considered a prerequisite for an artificial magnetic conductor, a periodic structure is not necessarily required to carry out the invention according to the present disclosure.

[0182] The artificial magnetic conductor described in the present disclosure consists of rows of conducting rods. To stop the electromagnetic waves leaking away from the waveguide surface, it has thus far been considered crucial that at least two rows of conducting rods exist on one side of the waveguide element(s), with these rows of conducting rods extending along the waveguide element(s) (rib(s)). The reason for this is that at least two rows of conducting rods are required for the waveguide to have a "period".However, according to an investigation by the inventors, even when only one row of conducting rods exists between two parallel waveguide elements, the intensity of a signal transmitting from one waveguide element to the other can be suppressed to -10 dB or less, which is a practically sufficient value in many applications. The reason why such a sufficient level of separation is achieved with only an imperfect periodic structure is currently unclear. However, in light of this fact, the concept of an "artificial magnetic conductor" is extended in the present disclosure, for the sake of convenience, to also include a structure with only one row of conducting rods. (Application example 1: On-board radar system>

[0183] As an application example for the slot array antenna described above, a case of an onboard radar system with a slot array antenna will be described next. A transmitting wave used in an onboard radar system can have a frequency of, for example, a 76-gigahertz (GHz) band, which has a wavelength λo of approximately 4 mm in free space.

[0184] In automotive safety technology, for example in collision avoidance systems or automated driving, it is particularly important to identify one or more vehicles (targets) that are ahead of the vehicle. Techniques for estimating the directions of incoming waves using a radar system are currently under development as methods for identifying vehicles.

[0185] Fig. Figure 26 shows a vehicle 500 and a vehicle 502 ahead, which is traveling in the same lane as the vehicle 500. The vehicle 500 has an onboard radar system that includes a slotted array antenna according to one of the embodiments described above. When the onboard radar system of the vehicle 500 transmits a high-frequency signal, the signal reaches the vehicle 502 ahead and is reflected by it, so that part of the signal returns to the vehicle 500. The onboard radar system receives this signal to calculate the position of the vehicle 502 ahead, its distance, its speed, etc.

[0186] Fig. Figure 27 shows the on-board radar system 510 of the vehicle 500. The on-board radar system 510 is located inside the vehicle. More specifically, the on-board radar system 510 is arranged on a surface of the rearview mirror that is opposite to its reflective surface. From inside the vehicle, the on-board radar system 510 transmits a high-frequency signal in the direction of travel of the vehicle 500 and receives one or more signals arriving from that direction.

[0187] The onboard radar system 510 from this application example comprises a slotted array antenna according to an embodiment of the present disclosure. The slotted array antenna can have a plurality of waveguide elements that are parallel to one another. They are arranged such that the plurality of waveguide elements each extends in a direction that coincides with the vertical direction, and that the plurality of waveguide elements is arranged in a direction that coincides with the horizontal direction. As a result, the lateral and vertical dimensions of the plurality of slots, viewed from the front, can be further reduced.

[0188] Example dimensions for an antenna device using the array antenna described above could be 60 mm (width) x 30 mm (length) x 10 mm (depth). It should be noted that this is a very small size for a millimeter-wave radar system operating in the 76 GHz band.

[0189] It is noted that many conventional on-board radar systems are mounted externally on the vehicle, for example, at the very front. This is because the on-board radar system is relatively large and therefore difficult to mount inside the vehicle, as in the present disclosure. The 510 on-board radar system from this application example can be installed inside the vehicle, as described above, but can also be mounted at the very front. Since the space required for the on-board radar system is reduced at the front, the arrangement of other components is simplified.

[0190] The application example allows for a narrow interval between a multitude of waveguide elements (ribs) used in the transmitting antenna, which also narrows the interval between a multitude of slots arranged opposite to a number of adjacent waveguide elements. This reduces the effects of grid lobes. For example, no forward-directed grid lobes occur if the interval between the centers of two laterally adjacent slots is shorter than the free-space wavelength λo of the transmitted wave (i.e., less than approximately 4 mm). Therefore, the effects of grid lobes are reduced. It is noted that grid lobes occur when the interval in which the antenna elements are arranged in an array is greater than half the wavelength of an electromagnetic wave.If the interval in which the antenna elements are arranged in an array is smaller than the wavelength, no grid lobes occur in the forward direction. Therefore, if no beam steering is used to transmit phase differences between the radio waves emitted from the individual antenna elements forming an array antenna, grid lobes have essentially no effect as long as the interval in which the antenna elements are arranged in an array is smaller than the wavelength. The directivity of the transmitting antenna can be adjusted by setting the array factor. A phase shifter can be provided to allow for individual adjustment of the phases of electromagnetic waves transmitted over multiple waveguide elements.To avoid the effects of grid lobes, it is preferable in this case that the interval between the antenna elements is smaller than the free-space wavelength λo of the transmitted wave. Grid lobes still occur in this case because the phase shift is increased. However, if the intervals between the antenna elements are reduced to less than half the free-space wavelength λo of the transmitted wave, no grid lobes occur, regardless of the phase shift. By providing a phase shifter, the directivity of the transmitting antenna can be changed in any desired direction. Since the construction of a phase shifter is known, its description is omitted.

[0191] A receiving antenna, as described in the application example, is capable of reducing the reception of reflected waves associated with grating lobes, thus improving the accuracy of the processing described below. An example of a receiving process is described below.

[0192] Fig. Figure 28A shows a relationship between an array antenna AA of the 510 onboard radar system and several incoming waves k (k: an integer from 1 to K; the same applies throughout. K is the number of targets present at different azimuths). The array antenna AA has M antenna elements in a linear array. An antenna can, in principle, be used for both transmitting and receiving, and therefore the array antenna AA can be used for either a transmitting or a receiving antenna. An example procedure for processing an incoming wave received by the receiving antenna is described below.

[0193] The array antenna AA receives multiple incoming waves arriving simultaneously at different angles. Some of these multiple incoming waves may be waves emitted from the transmitting antenna of the same 510 onboard radar system and reflected by one or more targets. Additionally, some of the multiple incoming waves may be direct or indirect waves emitted by other vehicles.

[0194] The angle of incidence of each incoming wave (i.e., an angle representing the direction of its arrival) is an angle referenced to the broad side B of the array antenna AA. The angle of incidence of an incoming wave represents an angle with respect to a direction perpendicular to the direction of the line along which the antenna elements are arranged in an array.

[0195] Now, let us consider a k-th arriving wave. If K waves arrive at the array antenna from K targets located at different azimuths, a "k-th arriving wave" means an arriving wave with an angle of incidence θ. k has been identified.

[0196] Fig. Figure 28B shows the array antenna AA, which receives the k-th arriving wave. The signals received by the array antenna AA can be expressed by Equation 1 as a "vector" with M elements. S=[S1,S2,...SM]T

[0197] In the equation above, s m(where m is an integer from 1 to M; this also applies in the following) the value of a signal received by an m-th antenna element. The superscript T denotes transposition. S is a column vector. The column vector S is defined by the product of a multiplication of a direction vector determined by the construction of the array antenna (called the steering vector or mode vector) and a complex vector representing a signal from the respective target (also called the wave source or signal source). If the number of wave sources is K, the waves of signals arriving at each individual antenna element from the respective K wave sources are linearly superimposed. In this state, sm can be expressed by Equation 2. Sm=∑k=1Kak exp{j(2πλdmsinθk+φk)}

[0198] In equation 2, α denotes k , θ k and φ kThe amplitude, angle of incidence, or initial phase of the k-th arriving wave. Furthermore, λ denotes the wavelength of an arriving wave, and j is an imaginary unit.

[0199] As can be seen from equation 2, sm is expressed as a complex number consisting of a real part (Re) and an imaginary part (Im).

[0200] If this is further generalized by taking noise (intrinsic noise or thermal noise) into account, the array received signal X can be expressed as equation 3. X=S+N

[0201] N is a vector expression for noise.

[0202] The signal processing circuit uses the array received signal X, expressed by equation 3, to generate a spatial covariance matrix Rxx (Gh 4) of incoming waves and further determines eigenvalues ​​of the spatial covariance matrix Rxx. Rxx=XXH=[Rxx11…Rxx1M⋮⋱⋮RxxM1…RxxMM]

[0203] In the equation above, the superscript H represents the complex conjugate transposition (Hermitian conjugate).

[0204] For eigenvalues, the number of eigenvalues ​​with values ​​equal to or greater than a predetermined value defined based on thermal noise (signal-space eigenvalues) corresponds to the number of arriving waves. Angles are then calculated that yield the highest probability with respect to the directions of incidence of reflected waves (i.e., the maximum probability), thus identifying the number of targets and the angles at which each target is located. This process is known as a maximum probability estimation technique.

[0205] See next Fig. 29. Fig. Figure 29 is a block diagram showing an example basic construction of a vehicle driving control unit 600 according to the present disclosure. The in Fig. The vehicle driving control unit 600 shown in Figure 29 comprises a radar system 510 mounted in a vehicle and an electronic driver assistance control unit 520 connected to the radar system 510. The radar system 510 includes an array antenna AA and a radar signal processing unit 530.

[0206] The AA array antenna features a multitude of antenna elements, each of which emits a received signal in response to one or more incoming waves. As mentioned earlier, the AA array antenna is capable of radiating a high-frequency millimeter wave.

[0207] In the radar system 510, the array antenna AA must be mounted on the vehicle, while at least some of the functions of the radar signal processing unit 530 can be implemented by a computer 550 and a database 552 located external to the vehicle's driving control unit 600 (e.g., outside the vehicle itself). In this case, the sections of the radar signal processing unit 530 located in the vehicle can be permanently or intermittently connected to the computer 550 and the database 552 located external to the vehicle, enabling bidirectional transmission of signals or data. These transmissions can be carried out via a communication device 540 of the vehicle and a commonly available communication network.

[0208] The database 552 can store a program that defines various signal processing algorithms. The content of the data and the program required for the operation of the radar system 510 can be updated externally via the communication device 540. Thus, at least some of the functions of the radar system 510 can be implemented externally to the vehicle itself using cloud computing technology (which includes the interior of another vehicle). For an "onboard" radar system in the sense of the present disclosure, it is therefore not necessary for all components to be mounted inside the (own) vehicle. However, for the sake of simplicity, the present application describes an implementation in which all components according to the present disclosure are mounted in a single vehicle (i.e., the own vehicle), unless otherwise specified.

[0209] The radar signal processing unit 530 includes a signal processing circuit 560. The signal processing circuit 560 receives signals directly or indirectly from the array antenna device AA and inputs the received signals, or one or more secondary signals generated from the received signals, into an incoming wave estimator AU. Part or all of the circuit (not shown) that generates one or more secondary signals from the received signals need not be located within the signal processing circuit 560. Part or all of such circuitry (preprocessing circuit) may be located between the array antenna AA and the radar signal processing unit 530.

[0210] The 560 signal processing circuit is configured to perform calculations using the received signals or secondary signal(s) and to output a signal indicating the number of arriving waves. In accordance with the present usage, a "signal indicating the number of arriving waves" can be defined as a signal indicating the number of vehicles ahead of the vehicle itself (which may be one or more vehicles).

[0211] The 560 signal processing circuit can be configured to perform a variety of signal processing operations that are achievable by known radar signal processing devices. For example, the 560 signal processing circuit can be configured to execute "super-resolution algorithms" such as the MUSIC, ESPRIT, or SAGE methods, or other algorithms for estimating the direction of incidence with relatively low resolution.

[0212] The in Fig. The incident wave estimator AU shown in Figure 29 estimates an angle representing the azimuth of each incoming wave using an arbitrary incident direction estimation algorithm and outputs a signal indicating the estimation result. The signal processing circuit 560 estimates the distance to each target as the wave source of an incoming wave, the target's relative velocity, and the target's azimuth using a known algorithm executed by the incident wave estimator AU and outputs a signal indicating the estimation result.

[0213] In this disclosure, the term "signal processing circuit" is not limited to a single circuit but includes any implementation where a combination of several circuits is conceptually considered as a single functional part. The signal processing circuit 560 can be implemented by one or more system-on-a-chip (SoC) devices. For example, part or all of the signal processing circuit 560 can be an FPGA (field-programmable array), which is a programmable logic device (PLD). In this case, the signal processing circuit 560 has a variety of computational elements (e.g., general-purpose logic and multipliers) and a variety of memory elements (e.g., reference tables or memory blocks). Alternatively, the signal processing circuit 560 can be a set of general-purpose processor(s) and main memory device(s).The 560 signal processing circuit can be a circuit that includes one or more processor cores and one or more memory devices. These can function as the 560 signal processing circuit.

[0214] The electronic driver assistance control unit 520 is configured to provide driver assistance to the vehicle based on various signals output from the radar signal processing unit 530. The electronic driver assistance control unit 520 instructs various electronic control units to perform predetermined functions, such as an alarm function to prompt the driver to brake when the distance to a vehicle ahead (vehicle following distance) has become less than a predefined value; a brake control function; and an acceleration control function.For example, in the case of an operating mode that performs adaptive speed control of the vehicle, the electronic driver assistance control unit 520 sends predetermined signals to various electronic control units (not shown) and actuators to maintain the distance of the vehicle to a vehicle ahead at a predefined value or to maintain the vehicle's speed at a predefined value.

[0215] In the case of the MUSIC method, the signal processing circuit determines 560 eigenvalues ​​of the spatial covariance matrix and outputs a signal indicating the number of incoming waves, which shows the number of those eigenvalues ​​(“signal space eigenvalues”) that are greater than a predetermined value defined on the basis of thermal noise (thermal noise power).

[0216] See next Fig. 30. Fig. Figure 30 is a block diagram showing another example construction for the vehicle driving control unit 600. The radar system 510 in the vehicle driving control unit 600 is shown. Fig. 30 features an array antenna AA comprising an array antenna Rx (also called a receiving antenna) and an array antenna Tx (also called a transmitting antenna) designed only for receiving; and an object detection device 570.

[0217] At least one of the transmitting antennas, Tx, or the receiving antenna, Rx, has the waveguide structure described above. The transmitting antenna, Tx, radiates a transmission wave, which can be, for example, a millimeter wave. The receiving antenna, Rx, which is only for receiving, outputs a received signal in response to one or more incoming waves (e.g., millimeter wave(s)).

[0218] A transmit / receive circuit 580 sends a transmit signal for a transmit wave to the transmit antenna Tx and performs preprocessing for received signals from receive waves that are received at the receive antenna Rx. Part or all of the preprocessing can be performed by the signal processing circuit 560 in the radar signal processing unit 530. A typical example of preprocessing to be performed by the transmit / receive circuit 580 is to generate a beat signal from a received signal and to convert a received signal with an analog format into a received signal with a digital format.

[0219] A device comprising a transmitting antenna, a receiving antenna, a transmit / receive circuit, and a waveguide device that permits the propagation of an electromagnetic wave between the transmitting antenna, the receiving antenna, and the transmit / receive circuit is referred to in this specification as a "radar device." Furthermore, a device comprising, in addition to a radar device, a signal processing device (including a signal processing circuit), e.g., an object detection device, is referred to as a "radar system."

[0220] It is noted that, according to the present disclosure, the radar system can be used, without being limited to the implementation in which it is mounted in the vehicle itself, attached to the road or to a building.

[0221] Next, an example of a more specific design of the vehicle driving control unit 600 will be described.

[0222] Fig. Figure 31 is a block diagram showing an example of a more specific construction of the vehicle driving control unit 600. The in Fig. Figure 31 shows a vehicle driving control unit 600 comprising a radar system 510 and an on-board camera system 700. The radar system 510 comprises an array antenna AA, a transmit / receive circuit 580 connected to the array antenna AA, and a signal processing circuit 560.

[0223] The on-board camera system 700 comprises an on-board camera 710, which is mounted in a vehicle, and an image processing circuit 720, which processes an image or video captured by the on-board camera 710.

[0224] The vehicle driving control unit 600 from this application example includes an object detection unit 570, which is connected to the array antenna AA and the on-board camera 710, and an electronic driver assistance control unit 520, which is connected to the object detection unit 570. In addition to the radar signal processing unit 530 described above (including the signal processing circuit 560), the object detection unit 570 includes a transmit / receive circuit 580 and an image processing circuit 720. The object detection unit 570 detects a target on or near the road using not only the information obtained by the radar system 510, but also the information obtained by the image processing circuit 720.For example, while the vehicle is traveling in one of two or more lanes in the same direction, the image processing circuit 720 can distinguish which lane the vehicle is traveling in and feed this distinction result to the signal processing circuit 560. If the number and azimuth(s) of vehicles ahead are to be detected using a predetermined algorithm for estimating the direction of approach (e.g., the MUSIC method), the signal processing circuit 560 can provide more reliable information about the spatial distribution of vehicles ahead by accessing the information from the image processing circuit 720.

[0225] It is noted that the 700 on-board camera system is one example of a means of identifying the lane in which the vehicle is traveling. The vehicle's lane position can also be identified by any other means. For example, by using ultra-wideband (UWB) technology, it is possible to identify which of a multitude of lanes the vehicle is traveling in. It is well known that ultra-wideband technology is applicable to positioning and / or radar. The use of ultra-wideband technology increases the radar's range resolution, so that even when there are a large number of vehicles ahead, each individual target can be clearly detected based on distance differences. This allows for the accurate identification of the distance to a guardrail at the roadside or the median strip.The width of each lane is predefined by the laws of the respective country or similar regulations. Using this information, it becomes possible to identify the lane in which a vehicle is currently traveling. Ultra-wideband technology is one example. Radio waves based on any other wireless technology can also be used. Additionally, LiDAR (light detection and distance measurement) can be used in conjunction with radar. LiDAR is sometimes referred to as "laser radar."

[0226] The array antenna AA can be a generic millimeter-wave array antenna for onboard use. The transmitting antenna Tx in this application example radiates a millimeter wave as a transmit wave in front of the vehicle. A portion of the transmit wave is reflected by a target, typically a vehicle ahead, so that a reflected wave originates from the target as a wave source. A portion of the reflected wave reaches the array antenna (receiving antenna) AA as an incoming wave. Each of the multiple antenna elements of the array antenna AA outputs a received signal in response to one or more incoming waves. If the number of targets acting as wave sources of reflected waves is K (where K is an integer greater than or equal to 1), the number of incoming waves is Ki, but this number Ki of incoming waves is not known in advance.

[0227] In the example from Fig. Paragraph 29 assumes that the radar system 510 is provided as an integral unit, including the array antenna AA, on the rearview mirror. However, the number and positions of array antennas AA are not limited to a specific number or specific positions. An array antenna AA may be located on the rear surface of the vehicle to detect targets located behind the vehicle. Furthermore, multiple array antennas AA may be located on the front and rear surfaces of the vehicle. The array antenna(s) AA may be located inside the vehicle. Even if a horn antenna, whose individual antenna elements, as mentioned above, have horns, is to be used as the array antenna(s) AA, the array antenna(s) with such antenna elements may be located inside the vehicle.

[0228] The signal processing circuit 560 receives and processes the received signals that were received by the receiving antenna Rx and have undergone preprocessing by the transmit / receive circuit 580. This process includes feeding the received signals into the incident wave estimator AU or, alternatively, generating one or more secondary signals from the received signals and feeding the secondary signal(s) into the incident wave estimator AU.

[0229] In the example from Fig. In the object detection device 570, a selection circuit 596 is provided which receives the signal output from the signal processing circuit 560 and the signal output from the image processing circuit 720. The selection circuit 596 enables the input of the signal output from the signal processing circuit 560 or the signal output from the image processing circuit 720, or both signals, into the electronic driver assistance control unit 520.

[0230] Fig. Figure 32 is a block diagram showing a more detailed example construction of the radar system 510 according to this application example.

[0231] As in Fig. As shown in Figure 32, the array antenna AA has a transmitting antenna Tx that transmits a millimeter wave and receiving antennas Rx that receive incoming waves reflected from targets. Although only one transmitting antenna Tx is shown in the figure, two or more types of transmitting antennas with different characteristics may be provided. The array antenna AA has M antenna elements 111, 112, ..., 11 M on (where M is an integer equal to or greater than 3). In response to the incoming waves, the multitude of antenna elements 111, 112, ..., 11 M received signals s1, s2, ..., s M out of ( Fig. 28B).

[0232] In the array antenna AA, the antenna elements are 111 to 11. Mfor example, arranged in a linear array or a two-dimensional array at fixed intervals. Each incoming wave strikes the array antenna AA from a direction at an angle θ with respect to the normal of the plane in which the antenna elements 111 to 11 are located. M They are arranged in an array-like fashion. Thus, the direction of incidence of an incoming wave is defined by this angle θ.

[0233] When an incoming wave from a target strikes the array antenna AA, it approaches a plane wave that travels towards the antenna elements 111 to 11. M from azimuths of the same angle θ. If K waves arriving at the array antenna AA from K targets with different azimuths arrive at K targets, the individual arriving waves can be at different angles θ1 to θ1. K be identified.

[0234] As in Fig. As shown in Figure 32, the object detection device 570 includes the transmit / receive circuit 580 and the signal processing circuit 560.

[0235] The transmit / receive circuit 580 comprises a triangle wave generator 581, a VCO (voltage-controlled oscillator) 582, a distributor 583, a mixer 584, a filter 585, a switch 586, an A / D converter 587, and a controller 588. Although the radar system in this application example is configured to transmit and receive millimeter waves using the FMCW method, the radar system of the present disclosure is not limited to this method. The transmit / receive circuit 580 is configured to generate a beat signal based on a received signal from the array antenna AA and a transmitted signal from the transmitting antenna Tx.

[0236] The signal processing circuit 560 has a distance detection section 533, a velocity detection section 534, and an azimuth detection section 536. The signal processing circuit 560 is configured to process a signal from the A / D converter 587 in the transmit / receive circuit 580 and to output signals indicating the detected distance to the target, the relative velocity of the target, and the azimuth of the target, respectively.

[0237] First, the design and operation of the 580 transmit / receive circuit are described in detail.

[0238] The triangle wave generation circuit 581 generates a triangle wave signal and feeds it to the VCO 582. The VCO 582 outputs a transmit signal with a frequency modulated based on the triangle wave signal. Fig. Figure 33 is a diagram showing the frequency change of a transmitted signal modulated based on the signal generated by a triangle wave generator 581. This waveform has a modulation width Δf and a center frequency of f0. The transmitted signal with this modulated frequency is fed to the distributor 583. The distributor 583 allows the transmitted signal obtained from the VCO 582 to be distributed between the mixers 584 and the transmitting antenna Tx. Thus, the transmitting antenna radiates a millimeter wave with a frequency modulated in triangle waves, as shown in Figure 33. Fig. 33 shown.

[0239] In addition to the transmission signal, it shows Fig. Figure 33 is also an example of a received signal from an incoming wave reflected by a single vehicle ahead. The received signal is delayed relative to the transmitted signal. This delay is proportional to the distance between the vehicle and the vehicle ahead. Furthermore, the frequency of the received signal increases or decreases due to the Doppler effect, corresponding to the relative speed of the vehicle ahead.

[0240] When the received and transmitted signals are mixed, a beat signal is generated based on their frequency difference. The frequency of this beat signal (beat frequency) differs between a period in which the transmitted signal's frequency increases (rise) and a period in which the transmitted signal's frequency decreases (fall). Once a beat frequency for each period has been determined based on these beat frequencies, the distance to the target and the target's relative velocity are calculated.

[0241] Fig. Figure 34 shows a beat frequency fu in an "ascending" period and a beat frequency fd in a "declining" period. In the graph from Fig. Figure 34 shows the horizontal axis representing the frequency and the vertical axis the signal intensity. This graph is obtained by subjecting the beat signal to a time-frequency conversion. Once the beat frequencies fu and fd have been determined based on a known equation, the distance to the target and the target's relative velocity are calculated. In this application example, with the construction and operation described below, beat frequencies are obtained that correspond to the respective antenna element of the array antenna AA, thus enabling the estimation of a target's position information.

[0242] In the Fig. The example shown in 32 uses received signals from channels Ch1 to Ch M , which correspond to the respective antenna elements 111 to 11 MThe corresponding signals are each amplified by an amplifier and fed into the respective mixers 584. Each mixer 584 mixes the transmitted signal into the amplified received signal. This mixing generates a beat signal that corresponds to the frequency difference between the received and transmitted signals. The generated beat signal is fed into the corresponding filter 585. The filters 585 apply bandwidth control to the beat signals on channels Ch1 to Ch2. M and feed bandwidth-controlled beat signals to switch 586.

[0243] Switch 586 performs a switching operation in response to a sampling signal input from controller 588. Controller 588 can, for example, be a microcomputer. Based on a computer program stored in memory such as ROM, controller 588 controls the entire transceiver circuit 580. Controller 588 need not be located within the transceiver circuit 580, but can be located within the signal processing circuit 560. In other words, the transceiver circuit 580 can operate according to a control signal from the signal processing circuit 560. Alternatively, some or all functions of controller 588 can be implemented by a central processing unit that controls the entire transceiver circuit 580 and signal processing circuit 560.

[0244] After the beat signals on channels Ch1 to Ch MAfter passing through the respective filters 585, the signals are successively fed to the A / D converter 587 via switch 586. Synchronized with the sampled signal, the A / D converter 587 converts the beat signals on channels Ch1 to Ch2. M , which are entered from switch 586, are converted into digital signals.

[0245] The following section describes in detail the design and operation of the 560 signal processing circuit. In this application example, the distance to the target and the target's relative velocity are estimated using the FMCW method. While not limited to the FMCW method described below, the radar system can also be implemented using other methods, such as dual-frequency CW and spread spectrum techniques.

[0246] In the Fig. The signal processing circuit 560 shown in Figure 32 comprises: a memory 531, a receive intensity calculation section 532, a distance detection section 533, a velocity detection section 534, a DBF (digital beamforming) processing section 535, an azimuth detection section 536, a destination link processing section 537, a matrix generation section 538, a destination output processing section 539, and an incident wave estimation unit AU. As mentioned earlier, part or all of the signal processing circuit 560 can be implemented by an FPGA or by a set of general-purpose processor(s) and main memory device(s).The memory 531, the received intensity calculation section 532, the DBF processing section 535, the distance detection section 533, the velocity detection section 534, the azimuth detection section 536, the destination link processing section 537 and the incident wave estimation unit AU can be individual parts implemented in stand-alone hardware components or functional blocks of a single signal processing circuit.

[0247] Fig. Figure 35 shows an example implementation in which the signal processing circuit 560 is implemented in hardware, including a processor PR and a storage device MD. In this configuration of the signal processing circuit 560, a computer program stored in the storage device MD can perform the functions of the receive intensity calculation section 532, the DBF processing section 535, the distance detection section 533, the velocity detection section 534, the azimuth detection section 536, the target link processing section 537, the matrix generation section 538, and the incident wave estimation unit AU, as described in Figure 35. Fig. 32 are shown.

[0248] The signal processing circuit 560 in this application example is configured to estimate the position information of a vehicle ahead using any beat signal, converted to a digital signal, as a secondary signal of the received signal, and to output a signal indicating the estimation result. The following section describes in detail the design and operation of the signal processing circuit 560 in this application example.

[0249] For each of the channels Ch1 to Ch M Memory 531 stores a digital signal in signal processing circuit 560, which is output by A / D converter 587. Memory 531 can be a generic storage medium such as semiconductor memory, a hard disk, and / or an optical disk.

[0250] The received intensity calculation section 532 applies Fourier transformation to the respective beat signals for channels Ch1 to Ch M an (in the lower graph from Fig. (33 shown), which are stored in memory 531. In this specification, the amplitude of a complex number data after the Fourier transform is referred to as "signal intensity." The receive intensity calculation section 532 converts the complex number data of a received signal from one of the multiple antenna elements, or a sum of the complex number data of all received signals from the multiple antenna elements, into a frequency spectrum. Beat frequencies can be detected in the resulting spectrum, corresponding to the respective peak values ​​that indicate the presence and distance of targets (ahead vehicles). Calculating a sum of the complex number data of the received signals from all antenna elements allows for the averaging of the noise components, thereby improving the signal-to-noise ratio.

[0251] In the case where there is only one target, i.e., a vehicle ahead, as in Fig. As shown in Figure 34, the Fourier transform produces a spectrum with only one peak value in a period with increasing frequency (the "rise" period) and only one peak value in a period with decreasing frequency (the "fall" period). The beat frequency of the peak in the "rise" period is denoted by "fu", while the beat frequency of the peak in the "fall" period is denoted by "fd".

[0252] From the signal intensities of beat frequencies, the receive intensity calculation section 532 detects any signal intensity that exceeds a predefined value (threshold), thereby determining the presence of a target. Upon detecting a signal intensity peak, the receive intensity calculation section 532 outputs the beat frequencies (fu, fd) of the peak values ​​as the frequencies of the object of interest to the distance detection section 533 and the velocity detection section 534. The receive intensity calculation section 532 outputs information indicating the frequency modulation width Δf to the distance detection section 533 and outputs information indicating the center frequency f0 to the velocity detection section 534.

[0253] In the event that signal intensity peaks corresponding to multiple targets are detected, the receive intensity calculation section 532 finds connections between the rising and falling peak values ​​based on predefined conditions. Peaks determined to belong to signals from the same target are assigned the same number and are thus fed into the distance detection section 533 and the velocity detection section 534.

[0254] If there are multiple targets, after the Fourier transform, as many peaks as there are targets appear in the rise and fall parts of the beat signal. In proportion to the distance between the radar and a target, the received signal is further delayed, and the received signal in Fig. 33 shifts further to the right. Therefore, a beat signal acquires a higher frequency as the distance between the target and the radar increases.

[0255] Based on the beat frequencies fu and fd entered from the receive intensity calculation section 532, the distance detection section 533 calculates a distance R using the equation below and feeds it to the target connection processing section 537. R={c⋅T / (2⋅Δf)}⋅{(fu+fd) / 2}

[0256] Furthermore, the velocity detection section 534 calculates a relative velocity V using the equation below, based on the beat frequencies fu and fd entered from the receive intensity calculation section 532, and feeds it to the target link processing section 537. V={c / (2⋅f0)}⋅{(fu−fd) / 2}

[0257] In the equation that calculates the distance R and the relative velocity V, c is the speed of light, and T is the modulation period.

[0258] It is noted that the lower limit of the distance R resolution is expressed as C / (2Δf). Therefore, increasing Δf increases the distance R resolution. For example, if the frequency f0 is in the 76 GHz band, a Δf setting of approximately 660 megahertz (MHz) results in a distance R resolution on the order of 0.23 meters (m). Consequently, if two vehicles are traveling side-by-side ahead, the FMCW method may struggle to distinguish between one and two vehicles. In such a case, operating an algorithm for estimating the direction of incidence with extremely high angular resolution could be beneficial to separate the azimuths of the two vehicles ahead and enable detection. This could be achieved by utilizing phase differences between signals from antenna elements 111, 112, ...The DBF processing section 535 allows a Fourier transform of the incoming complex data corresponding to the respective antenna elements to be performed. This data has been Fourier-transformed with respect to the time axis and the direction in which the antenna elements are arranged in an array. The DBF processing section 535 then calculates spatial complex number data indicating the spectral intensity for each angular channel, as determined by the angular resolution, and outputs it to the azimuth detection section 536 for the respective beat frequencies.

[0259] The azimuth detection section 536 is designed to estimate the azimuth of a vehicle ahead. From the values ​​of spatial complex number data calculated for the respective beat frequencies, the azimuth detection section 536 selects the angle with the largest value and outputs it to the target link processing section 537 as the azimuth at which an object of interest exists.

[0260] It should be noted that the procedure for estimating the angle θ, which indicates the direction of incidence of an incoming wave, is not limited to this example. Various algorithms for estimating the direction of incidence, which have already been mentioned, can be used.

[0261] The target link processing section 537 calculates absolute values ​​of the differences between the respective distance, relative velocity, and azimuth values ​​of the object of interest calculated in the current cycle and the respective distance, relative velocity, and azimuth values ​​of the object of interest calculated one cycle earlier and read from memory 531. If the absolute value of each difference is less than a value defined for that value, then the target link processing section 537 determines that the target detected one cycle earlier and the target detected in the current cycle are identical. In this case, the target link processing section 537 increments the number of target link processes read from memory 531 by one.

[0262] If the absolute value of a difference is greater than predetermined, the target link processing section 537 determines that a new object of interest has been detected. Target link processing section 537 stores the respective values ​​of the distance, relative velocity, and azimuth of the object of interest, calculated in the current cycle, as well as the count of target link processes for this object of interest, in memory 531.

[0263] In the 560 signal processing circuit, the distance to the object of interest and its relative speed can be detected by using a spectrum obtained through a frequency analysis of beat signals, which are signals generated on the basis of received reflected waves.

[0264] Matrix generation section 538 generates a spatial covariance matrix by using the respective beat signals for channels Ch1 to ChM (lower graph in Fig. 33), which are stored in memory 531. In the spatial covariance matrix from equation 4, each component is the value of a beat signal, expressed in terms of real and imaginary parts. Furthermore, the matrix generation section 538 determines eigenvalues ​​of the spatial covariance matrix Rxx and inputs the resulting eigenvalue information into the incident wave estimation unit AU.

[0265] When a large number of signal intensity peaks corresponding to multiple objects of interest are detected, the receive intensity calculation section 532 numbers the peak values ​​in both the rise and fall parts, starting with those at lower frequencies, and outputs them to the destination output processing section 539. In the rise and fall parts, peaks with the same number correspond to the same object of interest. The identification numbers are to be considered as the numbers assigned to the objects of interest. For easier illustration, a reference line from the receive intensity calculation section 532 to the destination output processing section 539 is shown in Fig. 32 omitted for the sake of simplicity.

[0266] If the object of interest is a structure ahead, the Destination Output Processing Section 539 outputs the identification number of that object of interest, indicating a destination. When receiving determination results for multiple objects of interest, all of which are structures ahead, the Destination Output Processing Section 539 outputs the identification number of any object of interest located in the vehicle's lane, indicating the object position information and where a destination is located.When receiving determination results for multiple objects of interest such that they are all structures ahead and that there are two or more objects of interest in the lane of the vehicle, the target output processing section 539 also outputs the identification number of an object of interest that is assigned to the highest count of targets read from the link processing memory 531 as the object position information that indicates where a target is located.

[0267] Again with reference to Fig. Section 31 describes an example where the on-board radar system 510 is integrated into the Fig. The example construction shown in Figure 31 incorporates the image processing circuit 720. This circuit captures information about an object from the video and uses this object information to determine its target position. For example, the image processing circuit 720 is designed to estimate distance information about an object by detecting its depth value in a captured video, or to detect size information and the like from characteristic values ​​in the video, thus determining the object's position.

[0268] The selection circuit 596 selectively transmits position information received from the signal processing circuit 560 or the image processing circuit 720 to the electronic driver assistance control unit 520. For example, the selection circuit 596 compares a first distance, i.e., the distance from the vehicle to a detected object, as contained in the object position information from the signal processing circuit 560, with a second distance, i.e., the distance from the vehicle to the detected object, as contained in the object position information from the image processing circuit 720, and determines which is closer to the vehicle. For example, based on the result of this determination, the selection circuit 596 can select the object position information indicating a closer distance to the vehicle and output it to the electronic driver assistance control unit 520.If the determination result indicates that the first distance and the second distance have the same value, the selection circuit 596 can output either one of them or both to the electronic driver assistance control unit 520.

[0269] If information is input from the receive intensity calculation section 532 indicating that no potential target exists, the target output processing section 539 ( Fig. 32) The object position information returns zero, indicating that no target is present. The selection circuit 596 then selects, based on the object position information from the target output processing section 539, by comparing it with a predefined threshold, either the object position information from the signal processing circuit 560 or the object position information from the image processing circuit 720 for use.

[0270] Based on predefined conditions, the electronic driver assistance control unit 520, upon receiving position information of an object ahead from the object detection unit 570, performs a control action to make operation safer or easier for the driver of the vehicle, according to the distance and size indicated by the object position information, the vehicle's speed, road conditions such as rain, snow, or clear weather, or other conditions. For example, if the object position information indicates that no object has been detected, the electronic driver assistance control unit 520 can send a control signal to an acceleration control circuit 526 to increase the engine speed up to a predefined speed, thus controlling the acceleration control circuit 526 to perform an operation equivalent to depressing the accelerator pedal.

[0271] If the object position information indicates that an object has been detected, the electronic driver assistance control unit 520, when it is determined that the object is within a predetermined distance of the vehicle, controls the brakes via a brake control circuit 524 using a brake-by-wire system or the like. In other words, it performs a speed reduction operation to maintain a constant vehicle distance. Upon receiving the object position information, the electronic driver assistance control unit 520 sends a control signal to an alarm control circuit 522 to control the illumination of a lamp or the playback of audio via a speaker provided in the vehicle, thus informing the driver of the approach of an object ahead.Upon receiving object position information, including a spatial distribution of vehicles ahead, the electronic driving assistance control unit 520 can, if the driving speed is within a predefined range, automatically facilitate steering to the left or right or control the hydraulic pressure on the steering wheel side to force a change in direction of the wheels, thereby providing assistance in collision prevention with respect to the object ahead.

[0272] The object detection device 570 can be configured to select continuous tracking and output object position information from the signal processing circuit 560 with priority when object position information that was continuously detected for some time in the previous detection cycle by the selection circuit 596, but is not detected in the current detection cycle, is matched with object position information from a camera-detected video showing an object in front.

[0273] A specific example construction and example operation by which the selection circuit 596 can make a selection between the outputs from the signal processing circuit 560 and the image processing circuit 720 are disclosed in the specification of US Patent No. US 8 446 312 B2, the specification of US Patent No. US 8 730 096 B2 and the specification of US Patent No. US 8 730 099 B2. (First option)

[0274] In the onboard radar system from the above application example, the (sweep) condition for a single instance of FMCW frequency modulation (frequency modulated continuous wave), i.e., a time period required for such modulation (sweep time), is e.g. 1 millisecond, although the sweep time could be reduced to approximately 100 microseconds.

[0275] However, to achieve such a fast sweep condition, not only must the components involved in transmitting a wave be able to operate quickly, but also those involved in receiving under this sweep condition. For example, an A / D converter 587 ( Fig. 32) is required, which operates quickly under this sweep condition. The sampling frequency of the 587 A / D converter can, for example, be 10 MHz. The sampling frequency can also be faster than 10 MHz.

[0276] In the present variant, a relative velocity is calculated with respect to a target without using a frequency component based on Doppler shift. In this variant, the sweep time Tm = 100 microseconds, which is very short. The lowest frequency of a detectable beat signal, which is 1 / Tm, is 10 kHz in this case. This would correspond to a Doppler shift of a reflected wave from a target with a relative velocity of approximately 20 m / second. In other words, as long as a Doppler shift is used, it would be impossible to detect relative velocities equal to or less than this value. Therefore, a calculation method different from one based on Doppler shift is preferred.

[0277] As an example, this variant illustrates a process that utilizes a signal (upward beat signal) representing the difference between a transmitting and a received wave, acquired during an upward (rising) section where the transmitting wave increases in frequency. A single sweep time of FMCW is 100 microseconds, and its waveform is a sawtooth shape consisting only of an upward portion. In this variant, the signal wave generated by the triangle wave / CW wave generation circuit 581 has a sawtooth shape. The sweep width is 500 MHz. Since there are no Doppler shift-associated peaks to utilize, the process does not generate both an upward and a downward beat signal to exploit the peaks from each; instead, it relies on only one of these signals.Although the use of an upward beat signal is illustrated here, a similar process can also be carried out using a downward beat signal.

[0278] The A / D converter 587 ( Fig. 32) samples each upward beat signal at a sampling frequency of 10 MHz and outputs several hundred digital data points (hereinafter referred to as "sample data"). The generation of sample data is based on upward beat signals, for example, from the time a received wave is detected until a transmitted wave ends the transmission. It is noted that the process may be terminated once a certain number of sample data points have been acquired.

[0279] In this variant, 128 upward beat signals are sent / received in series, for each of which several hundred data samples are acquired. The number of upward beat signals is not limited to 128. It can be 256 or 8. Depending on the intended use, any number can be selected.

[0280] The resulting sample data is stored in memory 531. The receive intensity calculation section 532 applies a two-dimensional fast Fourier transform (FFT) to the sample data. Specifically, a first FFT (frequency analysis) process is performed for each sample obtained from a single sweep to generate a power spectrum. Next, the velocity detection section 534 performs a second FFT process on the processing results collected from all sweeps.

[0281] If the reflected waves originate from the same target, peak components in the power spectrum to be detected will have the same frequency in each sweep period. However, with different targets, the peak components will differ in frequency. The first FFT process can be used to separate multiple targets located at different distances.

[0282] In the case where the relative velocity with respect to a target is not zero, the phase of the upward beat signal changes slightly from sweep to sweep. In other words, the second FFT process yields a power spectrum whose elements are the data of frequency components associated with such phase changes, based on the respective results of the first FFT process.

[0283] The receive intensity calculation section 532 extracts peak values ​​in the above second power spectrum and sends them to the velocity detection section 534.

[0284] The velocity detection section 534 determines a relative velocity from the phase changes. For example, assume that a series of acquired upward beat signals undergoes phase changes through each phase θ [RXd]. Assuming that the transmitted wave has an average wavelength λ, this means that each time an upward beat signal is acquired, there is a change in distance of λ / (4π / θ). Since this change occurred over an interval of the upward beat signal transmission Tm (=100 microseconds), the relative velocity is determined as {λ / (4 / π / θ)} / Tm.

[0285] The processes described above allow us to obtain a relative velocity with respect to a target and a distance from the target. (Second option)

[0286] The Radar System 510 is capable of detecting a target using continuous wave (CW) signals at one or more frequencies. This method is particularly useful in environments where numerous reflected waves from stationary objects in the vicinity reach the Radar System 510, for example, when the vehicle is in a tunnel.

[0287] The 510 radar system has a receiving antenna array with five channels of independent receiving elements. With such a radar system, estimating the incident azimuth of incident reflected waves is only possible if four or fewer reflected waves are present simultaneously. With an FMCW-type radar, the number of reflected waves subjected to incident azimuth estimation simultaneously can be reduced by selecting only reflected waves from a specific distance. However, in an environment with a large number of stationary objects in the surrounding area, such as in a tunnel, it is as if there is a continuum of objects to reflect radio waves; therefore, even when limiting the reflected waves based on distance, the number of reflected waves may still not be equal to or less than four.However, every such stationary object in the vicinity has the same relative velocity with respect to the vehicle itself, and this relative velocity is greater than that assigned to any other vehicle traveling ahead. On this basis, such stationary objects can be distinguished from any other vehicle based on the magnitudes of their Doppler shifts.

[0288] Therefore, the 510 radar system performs the following process: It transmits continuous wave (CW) signals of multiple frequencies and, disregarding Doppler shift peaks corresponding to stationary objects in the received signals, detects a distance using one or more Doppler shift peaks with a smaller shift magnitude. Unlike the FMCW method, in the CW method, a frequency difference between a transmitted wave and a received wave can only be attributed to a Doppler shift. In other words, every peak frequency occurring in a beat signal can only be attributed to a Doppler shift.

[0289] In the description of this variant, a continuous wave used in the CW method is also referred to as a "continuous CW wave". As described above, a continuous CW wave has a constant frequency; that is, it is unmodulated.

[0290] Assume that the 510 radar system transmitted a continuous wave (CW) of frequency fp and detected a reflected wave of frequency fq from a target. The difference between the transmit frequency fp and the receive frequency fq is called the Doppler frequency, which approximates fp - fq = 2·Vr·fp / c. Here, Vr is the relative velocity between the radar system and the target, and c is the speed of light. The transmit frequency fp, the Doppler frequency (fp - fq), and the speed of light c are known. Therefore, the relative velocity Vr = (fp - fq)·c / 2fp can be determined from this equation. The distance to the target is calculated using phase information, as will be described later.

[0291] To detect the distance to a target using continuous wave (CW) technology, a dual-frequency CW method is employed. In this method, continuous CW waves of two slightly different frequencies are each transmitted for a specific period, and their respective reflected waves are detected. For example, if frequencies in the 76 GHz band were used, the difference between the two frequencies would be several hundred kHz. As will be described later, it is preferable to determine the difference between the two frequencies taking into account the minimum distance at which the radar is capable of detecting a target.

[0292] Assuming that the radar system 510 emits continuous wave CW at frequencies fp1 and fp2 (fp1 <fp2) sequentiell abgestrahlt hat und dass die beiden kontinuierlichen Wellen CW von einem einzigen Ziel reflektiert wurden, so dass reflektierte Wellen der Frequenzen fq1 und fq2 durch das Radarsystem 510 empfangen werden.

[0293] A first Doppler frequency is derived from the continuous wave CW at frequency fp1 and its reflected wave (frequency fq1). A second Doppler frequency is derived from the continuous wave CW at frequency fp2 and its reflected wave (frequency fq2). The two Doppler frequencies are essentially the same. However, due to the difference between frequencies fp1 and fp2, the complex signals of the respective received waves differ in phase. By using this phase information, a distance to the target can be calculated.

[0294] Specifically, the 510 radar system is capable of determining the distance R as R = c·Δφ / 4π(fp2-fp1). Here, Δφ denotes the phase difference between two beat signals: beat signal 1, which is obtained as the difference between the continuous wave CW of frequency fp1 and the reflected wave (frequency fq1) of the same frequency, and beat signal 2, which is obtained as the difference between the continuous wave CW of frequency fp2 and the reflected wave (frequency fq2) of the same frequency. The procedure for identifying the frequency fb1 of beat signal 1 and the frequency fb2 of beat signal 2 is identical to that used in the aforementioned case of a beat signal from a continuous wave CW of a single frequency.

[0295] It is noted that a relative velocity Vr is determined according to the 2-frequency CW method as follows. Vr=fb1⋅c / 2⋅fp1 or Vr=fb2⋅c / 2⋅fp2

[0296] Furthermore, the distance within which a distance to a target can be uniquely identified is limited to the distance determined by Rmax. <c / 2(fp2-fp1) definiert ist. Der Grund hierfür ist, dass aus einer reflektierten Welle von einem weiter entfernten Ziel resultierende Schwebungssignale ein Δφ erzeugen würden, das größer als 2π ist, so dass sie nicht von Schwebungssignalen unterscheidbar wären, die Zielen an näheren Positionen zugeordnet sind. Daher ist es vorzuziehen, die Differenz zwischen den Frequenzen der zwei kontinuierlichen Wellen CW so einzustellen, dass Rmax größer als die minimale detektierbare Distanz des Radars wird. Im Fall eines Radars, dessen minimale detektierbare Distanz 100 m beträgt, kann fp2-fp1 z.B. als 1,0 MHz vorgesehen sein. In diesem Fall ist Rmax = 150 m, so dass ein Signal von jedem Ziel aus einer Position jenseits von Rmax nicht detektiert wird. Im Fall der Einrichtung eines Radars, der zur Detektion bis zu 250 m fähig ist, kann fp2-fp1 z.B.The frequency range should be set to 500 kHz. In this case, Rmax = 300 m, so a signal from any target at a position beyond Rmax will also not be detected. If the radar has both an operating mode with a minimum detectable range of 100 m and a horizontal viewing angle of 120 degrees, and an operating mode with a minimum detectable range of 250 m and a horizontal viewing angle of 5 degrees, it is preferable to switch the fp2-fp1 value between 1.0 MHz and 500 kHz for operation in the respective operating mode.

[0297] A detection approach is known in which the distance to each target is detected by transmitting continuous wave (CW) at N different frequencies (where N is an integer equal to or greater than 3) and by using phase information from the respective reflected waves. According to this approach, the distance to up to N-1 targets can be accurately determined. A fast Fourier transform (FFT) is used as the processing method to achieve this. For a given N = 64 or 128, an FFT is performed on sampled data of a beat signal as the difference between a transmitted signal and a received signal for each frequency, yielding a frequency spectrum (relative velocity). Then, at the frequency of the CW wave, another FFT is performed on peaks of the same frequency to derive distance information. This will be described in more detail below.

[0298] For the sake of simplicity, a case is first described in which signals with three frequencies f1, f2, and f3 are transmitted while being switched over time. It is assumed that f1 > f2 > f3 and f1 - f2 = f2 - f3 = Δf. A transmission time of Δt is assumed for the signal waveform at each frequency. Fig. Figure 36 shows a relationship between three frequencies f1, f2 and f3.

[0299] The triangular wave / CW wave generation circuit 581 transmits via the transmitting antenna Tx ( Fig. 32) Continuous wave CW of frequencies f1, f2 and f3, each lasting for time Δt. The receiving antennas Rx receive reflected waves resulting from the reflection of the respective continuous wave CW from one or more targets.

[0300] Each mixer 584 mixes a transmit wave and a receive wave to generate a beat signal. The A / D converter 587 converts the beat signal, which is an analog signal, into, for example, several hundred digital data points (sample data).

[0301] Using the sampled data, the receive intensity calculation section 532 performs an FFT calculation. The FFT calculation yields frequency spectrum information of received signals for the respective transmit frequencies f1, f2, and f3.

[0302] The receive intensity calculation section then separates 532 peak values ​​from the frequency spectrum information of the received signals. The frequency of each peak value, which is predetermined or greater, is proportional to a relative velocity with respect to a target. Separating one or more peak values ​​from the frequency spectrum information of received signals is equivalent to separating one or more targets with different relative velocities.

[0303] Next, the receive intensity calculation section 532 measures spectrum information of peak values ​​of the same relative velocity or relative velocities within a predefined range with reference to each of the transmit frequencies f1 to f3.

[0304] Consider a scenario in which two targets, A and B, exist with approximately the same relative velocity but are located at different distances. A transmitted signal of frequency f1 is reflected by both targets A and B, resulting in received signals. The reflected waves from targets A and B essentially produce the same beat frequency. Therefore, the power spectra at the Doppler frequencies of the received signals, corresponding to their relative velocities, are obtained as a synthetic spectrum F1, which is formed by merging the power spectra of the two targets A and B.

[0305] Likewise, for each of the frequencies f2 and f3, the power spectra at the Doppler frequencies of the received signals are obtained according to their relative velocities as a synthetic spectrum F1, to which the power spectra of two targets A and B have been merged.

[0306] Fig. Figure 37 shows a relationship between the synthetic spectra F1 to F3 on a complex plane. In the directions of the two vectors forming each of the synthetic spectra F1 to F3, the right-hand vector corresponds to the power spectrum of a reflected wave from target A; i.e., in Fig. 37 the vectors f1A, f2A and f3A. In contrast, in the directions of the two vectors that form each of the synthetic spectra F1 to F3, the left vector corresponds to the power spectrum of a reflected wave from target B; i.e. in Fig. 37 the vectors f1B, f2B and f3B.

[0307] With a constant difference Δf between the transmit frequencies, the phase difference between the received signals corresponding to the respective transmit signals of frequencies f1 and f2 is proportional to the distance to a target. Therefore, the phase difference between vectors f1A and f2A and the phase difference between vectors f2A and f3A have the same value θA, where this phase difference θA is proportional to the distance to target A. Similarly, the phase difference between vectors f1B and f2B and the phase difference between vectors f2B and f3B have the same value θB, where this phase difference θB is proportional to the distance to target B.

[0308] Using a known method, the respective distances to targets A and B can be determined from the synthetic spectra F1 to F3 and the difference Δf between the transmission frequencies. This technique is disclosed, for example, in US Patent No. US 6,703,967 B1.

[0309] A similar processing method is also applicable if the transmitted signals have four or more frequencies.

[0310] It is noted that prior to transmitting continuous wave CW at N different frequencies, a process of determining the distance to each target and its relative velocity can be performed using the two-frequency CW method. From this process, under predetermined conditions, it is then possible to switch to a continuous wave CW transmission process at N different frequencies. For example, an FFT calculation can be performed using the respective beat signals at the two frequencies, and if the power spectrum of each transmit frequency undergoes a change of 30% or more over time, the process can be switched. The amplitude of a reflected wave from each target undergoes a large change over time due to multipath effects and the like.If a change of a predetermined magnitude or greater exists, it may be considered that there are potentially multiple objectives.

[0311] Furthermore, it is known that the CW method cannot detect a target if the relative velocity between the radar system and the target is zero, i.e., if the Doppler frequency is zero. However, if, for example, a pseudo-Doppler signal is determined using the following methods, it is possible to detect a target by using this frequency.

[0312] (Method 1) A mixer is added that causes a specific frequency shift in the output of a receiving antenna. By using a transmit signal and a receive signal with a shifted frequency, a pseudo-Doppler signal can be obtained.

[0313] (Method 2) A variable phase shifter is inserted between the output of a receiving antenna and a mixer to continuously introduce phase changes over time, thus adding a pseudo-phase difference to the received signal. By using a transmitted signal and a received signal with an added phase difference, a pseudo-Doppler signal can be obtained.

[0314] An example of a specific design and operation for introducing a variable phase shifter to generate a pseudo-Doppler signal according to method 2 is disclosed in Japanese patent publication no. JP 2004 - 257 848 A.

[0315] If targets with no or very low relative velocity need to be detected, the above-mentioned processes for generating a pseudo-Doppler signal can be used, or the system can be switched to a target detection process using the FMCW method.

[0316] Next, with reference to Fig. 38 describes a processing procedure to be carried out by the object detection device 570 of the on-board radar system 510.

[0317] The example below illustrates a case where continuous waves (CW) are transmitted at two different frequencies fp1 and fp2 (fp1 <fp2) übertragen werden und die Phaseninformationen einer jeden reflektierten Welle genutzt werden, um jeweils eine Distanz mit Bezug auf ein Ziel zu detektieren.

[0318] Fig. Figure 38 is a flowchart showing the procedure of a determination process for relative velocity and distance according to this variant.

[0319] At step S41, the triangle wave / CW wave generation circuit 581 generates two continuous CW waves with frequencies that are slightly apart, i.e., frequencies fp1 and fp2.

[0320] In step S42, the transmitting antenna Tx and the receiving antennas Rx perform a transmission / receive of the generated series of continuous CW waves. It is noted that the process from step S41 and the process from step S42 can be performed in parallel by the triangular wave / CW wave generation circuit 581 and the transmitting antenna Tx / receiving antenna Rx, instead of performing step S42 only after step S41 has been completed.

[0321] In step S43, each mixer 584 generates a difference signal by utilizing each transmit and receive wave, thus obtaining two difference signals. Each receive wave includes one received wave emanating from a stationary object and one received wave emanating from a target. Therefore, a process of identifying frequencies for use as beat signals is then performed. It is noted that the process from step S41, the process from step S42, and the process from step S43 can be performed in parallel by the triangle wave / CW wave generation circuit 581, the transmit antenna Tx / receive antenna Rx, and the mixers 584, instead of performing step S42 only after step S41 has been completed, or step S43 only after step S42 has been completed.

[0322] In step S44, the object detection device 570 identifies certain peak frequencies for each of the two difference signals as frequencies fb1 and fb2 of beat signals in such a way that these frequencies are equal to or less than a frequency that is predefined as a threshold value, but have amplitude values ​​that are equal to or greater than a predetermined amplitude value, and that the difference between the two frequencies is equal to or less than a predetermined value.

[0323] In step S45, the receive intensity calculation section 532 detects a relative velocity based on one of the two identified beat signal frequencies. The receive intensity calculation section 532 calculates the relative velocity, for example, according to Vr = fb1·c / 2·fρ1. It is noted that a relative velocity can be calculated using either of the two beat signal frequencies, which allows the receive intensity calculation section 532 to verify whether they match or not, thereby increasing the accuracy of the relative velocity calculation.

[0324] In step S46, the receive intensity calculation section 532 determines a phase difference Δφ between two beat signals 1 and 2 and determines a distance R=c·Δφ / 4π(fp2-fp1) to the target.

[0325] The processes described above can be used to detect the relative speed and distance to a target.

[0326] It is noted that continuous waves (CW) can be transmitted at N different frequencies (where N = 3 or more) and that by using phase information of the respective reflected wave, distances to multiple targets with the same relative speed, but at different positions, can be detected.

[0327] In addition to the radar system 510, the vehicle 500 described above may also have another radar system. For example, the vehicle 500 may also have a radar system with a detection range towards the rear or sides of the vehicle body. If a radar system with a detection range towards the rear of the vehicle body is installed, the radar system can monitor the rear and, if there is a risk of another vehicle rear-ending it, take action, for example, by triggering an alarm. If a radar system with a detection range towards the sides of the vehicle body is installed, the radar system can monitor an adjacent lane when the vehicle changes lanes, etc., and, if necessary, take action, for example, by triggering an alarm.

[0328] The applications of the Radar System 510 described above are not limited to onboard use. Rather, the Radar System 510 can be used as a sensor for various purposes. For example, it can be used as a radar to monitor the area around a house or any other building. Alternatively, it can be used as a sensor to detect the presence or absence of a person at a specific location indoors, or to detect whether such a person is moving, etc., without using optical images. (Additional details of the processing)

[0329] Further embodiments are described in connection with the 2-frequency CW or FMCW techniques for the array antennas described above. As already described, the receive intensity calculation section 532 applies in the example from Fig. 32 a Fourier transform onto the respective beat signals for channels Ch1 to Ch M on (lower graph from Fig. 33), which are stored in memory 531. These beat signals are complex signals so that the phase of the signal of interest for the calculation can be identified. This allows for the correct identification of the direction of an incoming wave. However, in this case, the computational load for a Fourier transform increases, so a larger circuit is required.

[0330] To solve this problem, a scalar signal can be generated as a beat signal. For each of a multitude of generated beat signals, two complex Fourier transforms can be performed with respect to the spatial axis direction, corresponding to the antenna array, and the time axis direction, corresponding to the passage of time, to obtain frequency analysis results. Consequently, with minimal computational effort, beam shaping can ultimately be achieved such that the directions of arrival of reflected waves are identifiable, allowing frequency analysis results to be obtained for the respective beams. US Patent No. US 6,339,395 B1 is a related document. (Optical sensor, e.g. camera, and millimeter wave radar)

[0331] Next, a comparison between the array antenna described above and conventional antennas will be presented, along with an application example utilizing both the array antenna and an optical sensor (e.g., a camera). It will be noted that LiDAR or similar devices can be used as the optical sensor.

[0332] A millimeter-wave radar is capable of directly detecting the distance to a target and its relative speed. Another advantage is that its detection performance is not significantly reduced at night (including twilight) or in adverse weather conditions such as rain, fog, or snowfall. On the other hand, two-dimensional target acquisition with a millimeter-wave radar is not as straightforward as with a camera. In contrast, two-dimensional target acquisition and shape recognition with a camera is relatively simple. However, a camera may not be able to image a target at night or in poor weather, which poses a significant problem. This issue is particularly relevant if water droplets have accumulated on the section of the radar through which exposure is to be ensured, or if visibility is limited by fog.This problem exists in a similar way for LIDAR or the like, which also concerns the field of optical sensors.

[0333] In response to increasing demand for safer vehicle operation, driver assistance systems (DAS) have been developed for several years to prevent collisions and similar incidents. A DAS uses a sensor, such as a camera or millimeter-wave radar, to capture an image in the direction of travel. If an obstacle is detected that is predicted to impede the vehicle's progress, the system automatically applies brakes or other braking mechanisms to prevent collisions. Such a collision avoidance function is expected to operate normally even at night or in adverse weather conditions.

[0334] Therefore, driver assistance systems with a so-called integrated design are becoming increasingly common. These systems incorporate a millimeter-wave radar sensor in addition to a conventional optical sensor such as a camera, thus enabling a detection process that utilizes both. Such a driver assistance system will be explained in more detail later.

[0335] On the other hand, increasingly higher expectations are placed on the capabilities of millimeter-wave radar itself. A millimeter-wave radar for onboard use primarily utilizes electromagnetic waves in the 76 GHz band. The antenna power is limited to a certain level according to the respective national laws or similar regulations. For example, in Japan it is limited to 0.01 W or less. Based on such restrictions, a millimeter-wave radar for onboard use is expected to provide the necessary performance, such as a detection range of 200 m or more; an antenna size of 60 mm or less; a horizontal detection angle of 90 degrees or more; a range resolution of 20 cm or less; and the capability for close-range detection within 10 m, and so on.Conventional millimeter-wave radars used microstrip lines as waveguides and patch antennas as antennas (hereinafter both referred to as "patch antennas"). However, achieving the aforementioned performance with a patch antenna has been difficult until now.

[0336] Using a slotted array antenna to which the technology of the present disclosure is applied, the inventors have achieved the aforementioned performance. As a result, a millimeter-wave radar has been realized that is smaller, more efficient, and more powerful than conventional patch antennas and the like. Furthermore, by combining this millimeter-wave radar with an optical sensor such as a camera, a compact, highly efficient, and high-performance integrated device has been realized, which did not previously exist. This is described in detail below.

[0337] Fig. Figure 39 is a diagram of a combined device in a vehicle 500, wherein the combined device comprises an on-board camera system 700 and a radar system 510 (hereinafter referred to as the millimeter-wave radar 510) with a slotted array antenna, to which the technology of the present disclosure is applied. Various embodiments are described below with reference to this figure. (Installation of the millimeter wave radar in the vehicle compartment)

[0338] A conventional millimeter-wave radar 510' based on a patch antenna is positioned behind and inside a grille 512 located at the front of a vehicle. An electromagnetic wave radiated from the antenna passes through the openings in the grille 512 and is emitted in front of the vehicle 500. In this case, there is no dielectric layer, such as glass, in the region through which the electromagnetic wave passes to reduce or reflect its energy. Consequently, an electromagnetic wave emitted by the millimeter-wave radar 510' based on a patch antenna travels a long distance, for example, to a target 150 m or more away. By receiving the reflected electromagnetic wave with its antenna, the millimeter-wave radar 510' is able to detect a target.Since the antenna is located behind and inwards of the vehicle's grille 512, the radar can be damaged if the vehicle collides with an obstacle. Furthermore, it can become contaminated with mud or similar substances during rain, and the dirt adhering to the antenna can impede the transmission and reception of electromagnetic waves.

[0339] Similar to conventional methods, the millimeter-wave radar 510, which includes a slotted array antenna according to an embodiment of the present disclosure, can be placed behind the grille 512, which is located at the front of the vehicle (not shown). This allows 100% utilization of the electromagnetic wave emitted by the antenna, thereby enabling long-range detection beyond the usual level, e.g., the detection of a target located at a distance of 250 m or more.

[0340] Furthermore, according to one embodiment of the present disclosure, the millimeter-wave radar 510 can also be located in the vehicle compartment, i.e., inside the vehicle. In this case, the millimeter-wave radar 510 is positioned inwards from the windshield 511 of the vehicle in order to fit into a space between the windshield 511 and a surface of the rearview mirror (not shown) that faces away from its reflective surface. In contrast, the conventional patch-antenna-based millimeter-wave radar 510 cannot be located inside the vehicle compartment primarily for the following two reasons. A first reason is its large size, which prevents it from being accommodated in the space between the windshield 511 and the rearview mirror.A second reason is that a forward-radiated electromagnetic wave is reflected by the windshield 511 and attenuates due to dielectric losses, so that it can no longer cover the desired distance. Therefore, when a conventional millimeter-wave radar based on patch antennas is placed inside the vehicle, for example, only targets located 100 m or less ahead can be detected. In contrast, a millimeter-wave radar according to one embodiment of the present disclosure is able to detect a target at a distance of 200 m or more despite reflection or attenuation at the windshield 511. This performance is equivalent to or even greater than that of a conventional millimeter-wave radar based on patch antennas placed outside the vehicle. (Combined construction based on millimeter wave radar and camera etc., placed in the vehicle compartment)

[0341] Currently, many driver assistance systems use an optical imaging device, such as a CCD camera, as the primary sensor. Typically, a camera or similar device is positioned inside the vehicle, inwards from the windshield 511, to compensate for adverse external environmental influences. To minimize the optical effect of raindrops and the like, the camera or similar device is placed in an area swept by the windshield wipers (not shown), but still inwards from the windshield 511.

[0342] Due to the need for increased vehicle performance, for example with regard to automatic braking, there has been a demand for several years for an automatic braking system or similar technology whose functionality is guaranteed regardless of the external environment. If the only sensor in the driver assistance system is an optical device such as a camera, the problem arises that reliable operation at night or in bad weather cannot be guaranteed. This has created a need for a driver assistance system that includes not only an optical sensor (such as a camera) but also millimeter-wave radar, using these for combined processing to achieve reliable operation even at night or in bad weather.

[0343] As previously described, a millimeter-wave radar incorporating the present slot array antenna can be placed inside a vehicle due to its reduced size and significantly increased efficiency of the emitted electromagnetic wave compared to a conventional patch antenna. Utilizing these properties, the millimeter-wave radar 510, which includes not only an optical sensor (on-board camera system) 700 such as a camera, but also a slot array antenna according to the present disclosure, allows for the following applications: Fig. Figure 39 shows a placement of both inwards from the windshield 511 of the vehicle 500. This resulted in the following novel effects. (1) The driver assistance system is easier to install on the vehicle 500. With the conventional millimeter-wave radar 510' based on patch antennas, a space behind the grille 512 at the front was previously required to accommodate the radar. Since this space could have certain features that affected the structural design of the vehicle, a change in the size of the radar device could necessitate a redesign of the structural layout. This difficulty is avoided by placing the millimeter-wave radar within the vehicle's interior. (2) More reliable operation can be achieved by placing the millimeter-wave radar (on-board camera system) 510 and the on-board camera system 700 in essentially the same position in the vehicle compartment as in Fig. As shown in Figure 40, the same radars can achieve, in particular, an identical field of view and line of sight, which facilitates the "alignment process" described below—that is, a process used to determine that the respective target information acquired by them originates from the same object. If, on the other hand, the millimeter-wave radar 510' were located behind the grille 512, which is situated at the front outside the vehicle compartment, its radar line of sight L would differ from a radar line of sight M when it is located inside the vehicle compartment, resulting in a large offset compared to the image acquired by the on-board camera system 700. (3) The reliability of the millimeter-wave radar device is improved. Since, as described above, the conventional patch-antenna-based millimeter-wave radar 510' is located behind the grille 512 at the front, it easily accumulates dirt and can be damaged even in a minor collision or similar incident. For these reasons, cleaning and functional checks are constantly required. Furthermore, if the position or orientation of the millimeter-wave radar is displaced by an accident or similar incident, realignment with respect to the camera is necessary, as described below. The likelihood of such occurrences is reduced by placing the millimeter-wave radar inside the vehicle compartment, thus avoiding the aforementioned difficulties.

[0344] In a driver assistance system of such an integrated construction, the optical sensor, e.g., a camera, and the millimeter-wave radar 510, which incorporates the present slotted array antenna, may have an integrated construction, i.e., be in a fixed position relative to each other. In this case, a specific relative positioning between the optical axis of the optical sensor, such as a camera, and the directionality of the antenna of the millimeter-wave radar should be maintained, as will be described later. If this driver assistance system with an integrated construction is fixed in the vehicle compartment of the vehicle 500, the optical axis of the camera, etc., should be adjusted so that it is oriented ahead of the vehicle in a specific direction. See the specification in US patent application number US 2015 / 0264230A1.US 2016 / 0264065A1, US patent application with publication number US 2017 / 0057421A1, US patent application with publication number US 2017 / 0057422A1, and US patent application with publication number US 2017 / 0064165A1. Related techniques relating to the camera are described in the specifications of US patent no. US 7355524B2 and US patent no. US 7420159B2.

[0345] For information on placing an optical sensor, such as a camera and a millimeter-wave radar, within the vehicle, see, for example, the specifications of US Patent No. 8604968, US Patent No. 8,614,640 B2, and US Patent No. 7,978,122 B2. However, at the time these patents were filed, only conventional antennas with patch antennas were known as millimeter-wave radars, and thus observation over sufficient distances was not possible. For example, the distance observable with a conventional millimeter-wave radar is estimated at a maximum of 100 to 150 meters. Furthermore, if a millimeter-wave radar is placed inwards from the windshield, its size obstructs the driver's field of vision in an impractical manner, hindering safe driving.In contrast, a millimeter-wave radar incorporating a slot array antenna according to an embodiment of the present invention can be placed inside the vehicle due to its small size and significantly increased efficiency of the radiated electromagnetic wave compared to that of a conventional patch antenna. This enables remote observation over a range of 200 m without obstructing the driver's field of vision. (Adjusting the mounting position between millimeter wave radar and camera, etc.)

[0346] When processing with a combined design (which may be referred to below as a "combined process"), it is desirable that an image obtained with a camera or the like and the radar information obtained with the millimeter wave radar are mapped onto the same coordinate system, since their deviation with respect to position and target quantity hinders joint processing between the two.

[0347] This includes an approach based on the following three aspects. (1) The optical axis of the camera or the like and the antenna directivity of the millimeter wave radar must have a certain fixed ratio.

[0348] It is necessary that the optical axis of the camera or similar device and the antenna directionality of the millimeter-wave radar are aligned. Alternatively, a millimeter-wave radar can have two or more transmitting antennas and two or more receiving antennas, with the directionivities of these antennas being intentionally designed to be different. It must therefore be ensured that at least one specific, known ratio exists between the optical axis of the camera or similar device and the directionivities of these antennas.

[0349] In the event that the camera or the like and the millimeter-wave radar have the aforementioned integrated construction, i.e., are in a fixed position relative to each other, the relative positioning between the camera or the like and the millimeter-wave radar remains fixed. Therefore, the aforementioned requirements are met with respect to such an integrated construction. In contrast, with a conventional patch antenna or the like, in which the millimeter-wave radar is placed behind the grille 512 of the vehicle 500, the relative positioning between them is normally adjusted according to (2) below.

[0350] (2) In an initial state (e.g. upon delivery) after installation on the vehicle, there is a specific fixed ratio between an image captured by the camera or the like and radar information from the millimeter wave radar.

[0351] The mounting positions of the optical sensor, such as a camera, and the millimeter-wave radar 510 or 510' on the vehicle 500 are determined as follows. At a predetermined position 800 ahead of the vehicle 500, a diagram or target suitable for radar observation is correctly positioned (hereinafter referred to as the "reference diagram" or "reference target," and collectively as the "reference point"). This is observed with an optical sensor, such as a camera, or with the millimeter-wave radar 510. The observation information regarding the observed reference point is compared with previously stored shape information or the like of the reference point, and the current offset information is quantified.Based on this offset information, the mounting positions of an optical sensor, such as a camera, and the millimeter-wave radar 510 or 510' are set or corrected by at least one of the following means. Any other means capable of producing similar results can also be used. (i) Adjusting the mounting positions of the camera and the millimeter-wave radar such that the reference point is located at a midpoint between the camera and the millimeter-wave radar. This adjustment may be made using an aid or tool, etc., provided separately. (ii) Determining the offset amount of the camera and the axis / directivity of the millimeter wave radar relative to the reference point and correcting these offset amounts of the directivity by image processing of the camera image and radar processing.

[0352] It should be noted that in the case where the optical sensor, such as a camera, and the millimeter-wave radar 510, which includes a slot array antenna according to an embodiment of the present disclosure, have an integrated construction, i.e., are in a fixed position relative to each other, when an offset of the camera or the radar is set with respect to the reference point, the amount of the offset also becomes known to the other, so that a check of the offset of the other with respect to the reference point is unnecessary.

[0353] Specifically, with regard to the onboard camera system 700, a reference diagram can be placed at a predetermined position 750, and an image captured by the camera is compared with advance information indicating where in the camera's field of view the reference diagram image should be located, thereby detecting an offset amount. Based on this, the camera is adjusted by at least one of the above means (i) and (ii). Next, the offset amount determined for the camera is translated into an offset amount for the millimeter-wave radar. Then, an adjustment of the offset amount with respect to the radar information is made by at least one of the above means (i) and (ii).

[0354] Alternatively, this can be done using the millimeter-wave radar 510. With respect to the millimeter-wave radar 510, a reference target can be placed at a predetermined position 800, and the radar information is compared with advance information indicating where in the field of view of the millimeter-wave radar 510 the reference target should be located, so that an offset amount is detected. Based on this, the millimeter-wave radar 510 is adjusted by at least one of the above means (i) and (ii). Next, the offset amount determined for the millimeter-wave radar is translated into an offset amount for the camera. Then, an offset amount adjustment is made with respect to the image information acquired by the camera by at least one of the above means (i) and (ii).

[0355] (3) Even after an initial state of the vehicle, a certain ratio is maintained between an image captured by the camera or the like and radar information from the millimeter wave radar.

[0356] It is generally assumed that an image captured by a camera or similar device and radar information from the millimeter-wave radar are initially fixed and hardly fluctuate, except in the event of a vehicle accident or similar incident. However, if an offset between them does occur, adjustment is possible using the following methods.

[0357] The camera is positioned, for example, so that sections 513 and 514 (characteristic points) that are characteristic of the vehicle fit within its field of view. The positions at which these characteristic points are actually imaged by the camera are compared with the information about the positions these characteristic points should occupy if the camera were correctly mounted, and any offset(s) between them are detected. Based on this detected offset(s), the position of each subsequently captured image can be corrected, thus compensating for any misalignment in the physical mounting position of the camera. If this correction sufficiently develops the performance required by the vehicle, the adjustment according to point (2) above may become unnecessary.Regularly performing this adjustment during the start-up or operation of the vehicle 500 makes it possible to compensate for the offset amount even if a camera offset or similar issue occurs again, which contributes to driving safety.

[0358] However, this method is generally considered to yield lower adjustment accuracy than the method mentioned above (2). When making an adjustment based on an image obtained by imaging a reference point with the camera, the azimuth of the reference point can be determined with high precision, making high adjustment accuracy easily achievable. However, since this method uses a part of the vehicle body instead of a reference point for adjustment, the accuracy of the azimuth determination is relatively difficult to improve. The resulting adjustment accuracy is therefore somewhat lower. Nevertheless, this can be effective as a corrective measure if the mounting position of the camera or similar device has changed significantly due to reasons such as an accident or a large external force acting on the camera or similar device within the vehicle, etc. (Image of the target detected by millimeter wave radar and camera or similar: alignment process)

[0359] In a combined process, it must be established that for a given target, an image of that target captured by a camera or similar device and radar information acquired by millimeter-wave radar refer to "the same target." For example, suppose that two obstacles (first and second obstacles), e.g., two bicycles, have appeared 500 meters ahead of the vehicle. These two obstacles are captured as camera images and detected as radar information by the millimeter-wave radar. At this point, the camera image and the radar information relating to the first obstacle must be superimposed in such a way that they both point toward the same target. Likewise, the camera image and the radar information relating to the second obstacle must be superimposed in such a way that they both point toward the same target.If the camera image of the first obstacle and the radar information of the second obstacle are mistakenly identified as relating to the same object, a serious accident can occur. Such a process of determining whether a target in the camera image and a target in the radar image relate to the same object may subsequently be referred to in this specification as the "matching process".

[0360] This calibration process can be implemented by various detection devices (or methods) described below. These are described in detail below. It is noted that each of the following detection devices is to be installed in the vehicle and comprises at least one millimeter-wave radar detection section, an image detection section (e.g., a camera) oriented in a direction superimposed on the detection direction of the millimeter-wave radar detection section, and a calibration section. The millimeter-wave radar detection section has a slot array antenna according to one of the embodiments of the present disclosure and acquires at least radar information in its own field of view. The image acquisition section acquires at least image information in its own field of view.The comparison section includes a processing circuit that compares a detection result from the millimeter-wave radar detection section with a detection result from the image detection section to determine whether the two detection sections are detecting the same target. The image detection section can consist of one, two, or more optical cameras, LiDAR, infrared radar, and ultrasonic radar. The following detection devices differ from one another with respect to the detection process at their respective comparison sections.

[0361] In a first detection device, the alignment section performs two alignments as follows. A first alignment includes, for a target of interest detected by the millimeter-wave radar detection section, obtaining distance and lateral position information of the same, and also finding a target that is closest to the target of interest from one or two or more targets detected by the image detection section, and detecting (a) combination(s) thereof.A second matching process involves, for a target of interest detected by the image detection section, obtaining distance and lateral position information for that target, and also finding the target closest to the target of interest from among one or more targets detected by the millimeter-wave radar detection section, and detecting a combination (or combinations) thereof. Furthermore, this matching process determines whether there is a matching combination (or combinations) of targets detected by the millimeter-wave radar detection section and the matching combination (or combinations) of targets detected by the image detection section. If a matching combination exists, it is then determined that the same object is being detected by both detection sections.In this way, a comparison is achieved between the respective targets detected by the millimeter wave radar detection section and the image detection section.

[0362] A related technique is described in the specification of US Patent No. 7,358,889 B2. In this publication, the image detection section is illustrated by a so-called stereo camera, which has two cameras. However, this technique is not limited to this. If the image detection section has a single camera, detected targets can optionally be subjected to an image recognition process or the like to obtain distance and lateral position information of the targets. Similarly, a laser sensor, such as a laser scanner, can be used as the image detection section.

[0363] In a second detection device, the matching section compares a detection result from the millimeter-wave radar detection section and a detection result from the image detection section at each predetermined time interval. If the matching section determines that the same target was detected by the two detection sections in the previous matching result, it performs a matching using that previous result. Specifically, the matching section compares a target currently detected by the millimeter-wave radar detection section and a target currently detected by the image detection section with the target that was determined to have been detected by the two detection sections in the previous matching result.The calibration section then determines, based on the calibration result for the target currently detected by the millimeter-wave radar detection section and the calibration result for the target currently detected by the image detection section, whether the two detection sections are detecting the same target or not. Instead of directly comparing the detection results of the two detection sections, this detection device performs a chronological comparison between the two detection results and a previous calibration result. Therefore, the detection accuracy is improved compared to a case where only an instantaneous calibration is performed, thus achieving a stable calibration. In particular, by using past calibration results, calibration is still possible even if the accuracy of the detection section temporarily decreases.Furthermore, this detection device is capable of easily performing a comparison between the two detection sections by using the previous comparison result.

[0364] During the current comparison, which utilizes the previous comparison result, the comparison section of this detection device, if it determines that the same object is being detected by both detection sections, excludes this specific object when performing the comparison between objects currently detected by the millimeter-wave radar detection section and objects currently detected by the image detection section. This comparison section then determines whether an identical object exists that is currently being detected by both detection sections. Thus, taking into account the result of the chronological comparison, the detection device also performs an instantaneous comparison based on two detection results acquired moment by moment. Consequently, the detection device is capable of reliably performing a comparison for every object detected during the current detection.

[0365] A related technique is described in the specification of US Patent No. 7,417,580 B2. In this publication, the image detection section is illustrated by a so-called stereo camera, which has two cameras. However, this technique is not limited to this. In the case where the image detection section has a single camera, detected targets can optionally be subjected to an image recognition process or the like to obtain distance and lateral position information of the targets. Similarly, a laser sensor, such as a laser scanner, can be used as the image detection section.

[0366] In a third detection device, the two detection sections and the comparison section perform target detection and comparisons at predetermined time intervals. The results of these detections and comparisons are stored chronologically in a storage medium, such as memory. Based on the rate of change of a target's size in the image, as detected by the image detection section, and the distance from the vehicle to the target and its rate of change (relative speed with respect to the vehicle), as detected by the millimeter-wave radar detection section, the comparison section then determines whether the target detected by the image detection section and the target detected by the millimeter-wave radar detection section are identical objects.

[0367] If, based on the position of the target in the image, as detected by the image detection section, and the distance from the vehicle to the target and / or their rate of change, as detected by the millimeter wave radar detection section, it is determined that these targets are an identical object, the matching section predicts a possibility of collision with the vehicle.

[0368] A related technique is described in the specification of US patent no. US 6 903 677 B2.

[0369] As described above, in a combined process, a millimeter-wave radar and an imaging device, such as a camera, compare an image acquired by the camera or the like with radar information acquired by the millimeter-wave radar. A millimeter-wave radar incorporating the aforementioned array antenna according to one embodiment of the present disclosure can be designed to be small in size and highly efficient. Therefore, high efficiency and size reduction, etc., can be achieved for the entire combined process, including the aforementioned comparison process. This improves the accuracy of target detection and enables safer vehicle control. (Other merged processes)

[0370] In a combined process, various functions are implemented based on a comparison process between an image acquired with a camera or similar device and radar information acquired with the millimeter-wave radar detection section. Examples of processing units that implement representative functions of a combined process are described below.

[0371] Each of the following processing units is to be installed in a vehicle and comprises at least: a millimeter-wave radar detection section for transmitting or receiving electromagnetic waves in a predetermined direction; an image acquisition section, such as a monocular camera, with a field of view superimposed on the field of view of the millimeter-wave radar detection section; and a processing section that extracts information from this data to perform target detection and the like. The millimeter-wave radar detection section acquires radar information within its own field of view. The image acquisition section acquires image information within its own field of view. One or two or more selected optical cameras, LiDAR, infrared radar, and ultrasonic radar may be used as the image acquisition section.The processing section can be implemented by a processing circuit connected to the millimeter-wave radar detection section and the image acquisition section. The following processing devices differ from one another with regard to the content of the processing performed by this processing section.

[0372] In the first processing stage, the processing section extracts a target from an image acquired by the image acquisition section. This target is recognized as the same target detected by the millimeter-wave radar detection section. In other words, a matching process is performed according to the aforementioned detection device. It then acquires information from the right and left edges of the extracted target image and derives approach lines. These lines are either straight lines or predetermined curved lines used to approximate the locations of the acquired right and left edges. The edge with the greater number of points lying on the approach line is selected as the true edge of the target. The lateral position of the target is then derived based on the position of the edge selected as the true edge.This allows for a further improvement in detection accuracy for a lateral position of the target.

[0373] A related technique is described in the specification of US patent no. US 8 610 620 B2.

[0374] In a second processing unit, the processing section modifies a detection threshold when determining the presence of a target. This threshold is used for verifying the presence of a target in radar information based on image data. For example, if a target image, which could be an obstacle to the vehicle's movement, has been confirmed by a camera or similar device, or if the presence of a target has been estimated, etc., the detection threshold for target detection by the millimeter-wave radar detection section can be optimized to obtain more accurate target information. If the probability of an obstacle's presence is high, the detection threshold is modified to ensure that this processing unit is activated.If, on the other hand, the probability of an obstacle being present is low, the threshold for determination is adjusted so that unwanted activation of this processing unit is prevented. This allows for appropriate activation of the system.

[0375] Furthermore, in this case, the processing section can use radar information to define a detection region for the image data and estimate the likelihood of an obstacle being present within that region. This results in a more efficient detection process.

[0376] A related technique is described in the specification of US patent no. US 7 570 198 B2.

[0377] In a third processing unit, the processing section performs a combined display operation in which images acquired from a variety of different imaging devices and a millimeter-wave radar detection section, along with an image signal based on radar information, are displayed on at least one display device. During this display process, horizontal and vertical synchronization signals are synchronized between the variety of imaging devices and the millimeter-wave radar detection section, and the system can selectively switch between the image signals from these devices to a desired image signal within a horizontal or vertical sampling period.This allows, based on the horizontal and vertical synchronization signals, the display of images from a large number of selected image signals side by side; and a control signal is sent from the display device to set a control operation in the desired imaging device and the millimeter wave radar detection section.

[0378] When multiple different display devices show various images or similar content, comparing these images becomes difficult. Furthermore, if the display devices are separate from the third processing unit itself, the unit's functionality is limited. The third processing unit would overcome these disadvantages.

[0379] A related technique is described in the specification of US patent no. US 6 628 299 B2 and the specification of US patent no. US 7 161561 B2.

[0380] In a fourth processing unit, the processing section, with reference to a target located ahead of a vehicle, instructs an image acquisition section and a millimeter-wave radar detection section to acquire an image and radar information containing that target. From this image information, the processing section determines a region containing the target. Furthermore, the processing section extracts radar information within this region and detects the distance between the vehicle and the target, as well as the relative speed between the vehicle and the target. Based on this information, the processing section determines the probability of a collision between the target and the vehicle. This enables the early detection of a potential collision with a target.

[0381] A related technique is described in the specification of US patent no. US 8 068 134 B2.

[0382] In a fifth processing unit, the processing section detects one or more targets ahead of the vehicle based on radar information or through a combined process based on radar and image information. The "target" includes any moving object such as other vehicles or pedestrians, lane markings indicated by white lines on the road, shoulders, and any stationary objects (including ditches, obstacles, etc.), traffic lights, pedestrian crossings, and the like that may be present. The processing section may include a GPS (Global Positioning System) antenna.Using a GPS antenna, the vehicle's position can be detected. Based on this position, a storage device (referred to as a map information database device) that stores road map information can be searched to determine a current position on the map. This current position on the map can be compared with one or more targets detected based on radar information or similar methods, thus enabling the vehicle's driving environment to be understood. Based on this information, the processing unit can identify any target that, in its assessment, might impede the vehicle's driving, find safer driving information, and, if appropriate, display this information on a screen to inform the driver.

[0383] A related technique is described in the specification of US patent no. US 6 191 704 B1.

[0384] The fifth processing unit may further include a data communication device (with communication circuits) that communicates with a map information database device located external to the vehicle. The data communication device can access the map information database device at intervals of, for example, once a week or once a month to download the latest map information. This allows the aforementioned processing to be carried out using the most up-to-date map information.

[0385] Furthermore, the fifth processing unit can compare the latest map information acquired during the aforementioned vehicle journey with information detected about one or more targets based on radar data, etc., in order to extract target information (hereinafter referred to as "map update information") not contained in the map information. This map update information can then be sent via the data communication device to the map information database device. The map information database device can store this map update information in conjunction with the map information contained in the database and update the current map information itself as needed.During the update process, individual map update information obtained from a large number of vehicles can be compared to verify the security of the update.

[0386] It is noted that this map update information may contain more detailed information than the map information maintained by any currently available map information database device. For example, commonly available map information may reveal schematic shapes of roads, but it typically does not include information such as the width of the shoulder, the width of any existing roadside ditch, newly occurring elevations or depressions, building shapes, and so on. It also does not include the elevations of the roadway and sidewalk, any possible connection of a sloping surface to the sidewalk, and so forth. Based on separately set conditions, the map information database device can store such detailed information (hereafter referred to as "map update detail information") in conjunction with the map information.Such map update details provide a vehicle (including the owner's vehicle) with information that is more detailed than the original map information, making it available not only for ensuring safe driving but also for other purposes. As used here, a "vehicle (including the owner's vehicle)" could be, for example, a car, a motorcycle, a bicycle, or any autonomous vehicle that may become available in the future, such as an electric wheelchair. The map update details are usable for the journey of any such vehicle. (Recognition via neural network)

[0387] Each of the first through fifth processing units can further include a complex recognition unit. The complex recognition unit can be located externally to the vehicle. In this case, the vehicle can have a high-speed data communication device that communicates with the complex recognition unit. The complex recognition unit can be formed from a neural network, which may include deep learning and the like. This neural network can, for example, be a convolutional neural network (hereinafter referred to as a "CNN"). A CNN, a neural network that has proven successful in image recognition, is characterized by having one or more sets of two layers: a convolutional layer and a pooling layer.

[0388] There are at least three types of information that can each be entered into a convolution layer in the processing unit: (1) Information based on radar information acquired by the millimeter wave radar detection section; (2) Information based on specific image information acquired by the image acquisition section based on radar information; or (3) combined information based on radar information and image information acquired by the image acquisition section, or information obtained on the basis of such combined information.

[0389] Based on information of any of the aforementioned types, or a combination thereof, product-sum operations are performed, corresponding to a convolution layer. The results are fed into the subsequent pooling layer, where data is selected according to a predetermined rule. In the case of maximum pooling, where a maximum value is chosen from pixel values, the rule might, for example, stipulate that a maximum value be selected for each division region in the convolution layer, with this maximum value being considered the value of the corresponding position in the pooling layer.

[0390] A complex detection system formed from a CNN can have a single set of a convolutional layer and a pooling layer, or a multitude of such sets cascaded in series. This enables accurate target detection based on radar and image information that may be present around a vehicle.

[0391] Related techniques are described in US Patent No. US 8 861 842 B1, in the specification of US Patent No. US 9 286 524 B1 and the specification of US Patent Application Publication No. US 2016 / 0140424 A1.

[0392] In a sixth processing unit, the processing section performs processing related to the headlight control of a vehicle. When a vehicle is traveling at night, the driver can check whether another vehicle or a pedestrian is ahead and control a beam of light from the vehicle's headlight(s) to prevent the driver of the other vehicle or the pedestrian from being dazzled by the vehicle's headlight(s). This sixth processing unit automatically controls the vehicle's headlight(s) using radar information or a combination of radar information and an image captured by a camera or similar device.

[0393] Based on radar information, or through a combined process of radar and image information, the processing unit detects a target corresponding to a vehicle or pedestrian ahead of the vehicle. In this case, a vehicle ahead can include a vehicle traveling in front, a vehicle or motorcycle in the oncoming lane, and so on. Upon detecting such a target, the processing unit issues a command to dim the beam(s) of the headlight(s). Upon receiving this command, the control unit (control circuitry), located internally within the vehicle, can control the headlight(s) to dim the emitted beam(s).

[0394] Related techniques are described in the specifications of US Patent No. US 6,403,942 B1, US Patent No. US 6,611,610 B1, US Patent No. US 8,543,277 B2, US Patent No. US 8,593,521 B2, and US Patent No. US 8,636,393 B2.

[0395] According to the processing described above by the millimeter-wave radar detection section and the combined process described above of the millimeter-wave radar detection section and an imaging device such as a camera, the millimeter-wave radar can be designed to be small and powerful, thus achieving high performance and size reduction, etc., for the radar processing or the entire combined process. This improves the accuracy of target detection and enables safer vehicle control. (Application example 2: Various monitoring systems (natural elements, buildings, roads, guarding, security)

[0396] A millimeter-wave radar (radar system) incorporating an array antenna according to one embodiment of the present disclosure also has a wide range of applications in the field of monitoring, which can include natural elements, weather, buildings, security, care, and the like. In such a monitoring system, a monitoring device comprising the millimeter-wave radar can, for example, be installed at a fixed location to continuously monitor the object(s) being monitored. The detection resolution of the millimeter-wave radar is adjusted with respect to the object(s) being monitored and set to an optimal value.

[0397] A millimeter-wave radar incorporating an array antenna according to an embodiment of the present disclosure is capable of detection using an electromagnetic wave with a high frequency of, for example, more than 100 GHz. Regarding the modulation band in the schemes used for radar detection, such as the FMCW method, the millimeter-wave radar currently achieves a wide band of more than 4 GHz, thus supporting the aforementioned ultra-wideband (UWB). It should be noted that the modulation band is related to the range resolution. With a conventional patch antenna, the modulation band was up to approximately 600 MHz, resulting in a range resolution of 25 cm. In contrast, a millimeter-wave radar associated with the present array antenna has a range resolution of 3.75 cm, indicating a performance comparable to that of a conventional LiDAR.While an optical sensor such as LiDAR is incapable of detecting a target at night or in bad weather, as mentioned above, a millimeter-wave radar is always capable of detection, regardless of whether it is day or night and irrespective of the weather. Consequently, a millimeter-wave radar associated with the present array antenna is available for a wide range of applications that were not possible with a millimeter-wave radar incorporating a conventional patch antenna.

[0398] Fig. Figure 41 is a diagram showing an example design for a millimeter-wave radar-based surveillance system 1500. The millimeter-wave radar-based surveillance system 1500 has at least one sensor section 1010 and one main section 1100. The sensor section 1010 has at least one antenna 1011 directed at the monitored object 1015, a millimeter-wave radar detection section 1012 that detects a target based on a transmitted or received electromagnetic wave, and a communication section (communication circuit) 1013 that transmits detected radar information.The main section 1100 comprises at least: a communication section (communication circuit) 1103, which receives radar information; a processing section (processing circuit) 1101, which performs predetermined processing based on the received radar information; and a data storage section (storage medium) 1102, in which older radar information and other information required for the predetermined processing, etc., are stored. Telecommunication links 1300 exist between the sensor section 1010 and the main section 1100, through which the sending and receiving of information and commands takes place. As used here, the telecommunication links can include, for example, a general-purpose communication network such as the Internet, a mobile communication network, dedicated telecommunication links, and so on.It is noted that the present surveillance system 1500 can be arranged such that the sensor section 1010 and the main section 1100 are directly connected instead of via telecommunications links. In addition to the millimeter-wave radar, the sensor section 1010 can also include an optical sensor such as a camera. This allows target detection through a combined process based on radar information and image information from the camera or the like, thereby enabling more complex detection of the monitored object 1015 or the like.

[0399] Examples of monitoring systems that embody these applications are described in detail below. (Natural Element Monitoring System)

[0400] A first monitoring system is a system that monitors natural elements (hereinafter referred to as the "natural element monitoring system"). With reference to Fig. Section 41 describes this natural element monitoring system. Monitoring objects 1015 of the natural element monitoring system 1500 can be, for example, a river, the sea surface, a mountain, a volcano, the ground surface, or the like. If the monitoring object 1015 is, for example, a river, the sensor section 1010, which is fixed in a fixed position, continuously monitors the water surface of the river 1015. This water surface information is continuously sent to a processing section 1101 in the main section 1100. If the water surface then reaches or exceeds a certain level, the processing section 1101 notifies a separate system 1200, which exists independently of the monitoring system (e.g., a weather observation monitoring system), via the telecommunications links 1300.Alternatively, processing section 1101 can send information to a system (not shown) that manages the lock, causing the system to automatically close a lock provided on the river 1015, etc. (not shown), upon instruction.

[0401] The Natural Element Monitoring System 1500 is capable of monitoring numerous sensor sections (1010, 1020, etc.) with a single main section (1100). When these sensor sections are distributed across a specific area, the water levels of rivers within that area can be recorded simultaneously. This allows for an assessment of how precipitation in this area might affect river levels, potentially leading to catastrophic consequences such as flooding. This information can be transmitted via the telecommunications links (1300) to a separate system (1200, e.g., a weather observation monitoring system). The separate system (1200, e.g., a weather observation monitoring system) can then use the transmitted information for weather observation or disaster forecasting in a different area.

[0402] The Natural Element Monitoring System 1500 is similarly applicable to any natural element other than a river. For example, in a monitoring system that tracks tsunamis or storm surges, the sea level is the object being monitored. It is also possible to automatically open or close a seagate in response to a rise in sea level. Alternatively, the object being monitored in a system that tracks landslides resulting from precipitation, earthquakes, or the like could be the ground surface of a mountainous region, and so on. (Traffic monitoring system)

[0403] A second monitoring system is one that monitors traffic (hereinafter referred to as the "traffic monitoring system"). The object of monitoring by this traffic monitoring system could be, for example, a level crossing, a specific railway line, an airport runway, a road junction, a specific road, a parking lot, etc.

[0404] If the monitored object is, for example, a level crossing, sensor section 1010 is positioned to monitor the interior of the crossing. In this case, sensor section 1010 can also include an optical sensor, such as a camera, in addition to the millimeter-wave radar. This allows for the detection of a target (monitored object) from multiple perspectives through a combined process based on radar and image information. The target information acquired by sensor section 1010 is transmitted to main section 1100 via telecommunications links 1300. Main section 1100 gathers other information (e.g., timetable information) that may be necessary for more complex detection or control processes and issues necessary control instructions or similar based on this information.As used here, a necessary control instruction might be, for example, an instruction to stop a train if a person, vehicle, etc. is found in the level crossing when it is closed.

[0405] If the object being monitored is a runway at an airport, for example, a multitude of sensor sections 1010, 1020, etc., can be placed along the runway to calibrate it to a predetermined resolution, e.g., a resolution that allows the detection of a foreign object measuring 5 cm by 5 cm on the runway. The monitoring system 1500 continuously monitors the runway, regardless of whether it is day or night and irrespective of the weather. This function is made possible by the ability of the millimeter-wave radar, according to one embodiment of the present disclosure, to support UWB. Furthermore, since the present millimeter-wave radar device can be designed to be small, high-resolution, and low-cost, it represents a realistic solution for covering the entire runway surface from one end to the other.In this case, the main section 1100 manages the numerous sensor sections 1010, 1020, etc., under integrated control. If a foreign object is detected on the runway, the main section 1100 transmits information regarding the object's position and size to an air traffic control system (not shown). Upon receiving this information, the air traffic control system temporarily prohibits takeoffs and landings on that runway. Meanwhile, the main section 1100 transmits information regarding the foreign object's position and size to a dedicated vehicle, such as one that automatically cleans the runway surface. Upon receiving this information, the cleaning vehicle can autonomously move to the location of the foreign object and remove it automatically. Once the removal of the foreign object is complete, the cleaning vehicle transmits a completion notification back to the main section 1100.Main section 1100 then confirms that sensor section 1010, or similar, which detected the foreign object, now reports that "no foreign object is present" and that it is now safe, and notifies the air traffic control system accordingly. Upon receiving this information, the air traffic control system can lift the ban on takeoffs and landings on the runway.

[0406] If the object being monitored is a parking lot, it may also be possible, for example, to automatically detect which parking spaces are currently free. A related technique is described in the specification of US Patent No. US 6,943,726 B2. (Security monitoring system)

[0407] A third type of surveillance system is a system that monitors an intruder on private property or in a house (hereinafter referred to as a "security surveillance system"). The object of surveillance of this security surveillance system could be, for example, a specific region within a private property or house, etc.

[0408] If the object being monitored is private property, the sensor section(s) 1010 can be placed at one, two, or more locations from which it can monitor the same area. In this case, the sensor section(s) can, in addition to the millimeter-wave radar 1010, also include an optical sensor such as a camera, which allows for the detection of a target (object being monitored) from multiple perspectives through a combined process based on radar and image information. The target information acquired by the sensor section(s) 1010 is transmitted to the main section 1100 via the telecommunications links 1300. The main section 1100 collects other information (e.g.,Reference data or the like, necessary for correctly identifying whether the intruder is a person or an animal (such as a dog or a bird), which may be required for a more complex detection process or control, and issues necessary control instructions or the like based on this. As used here, a necessary control instruction might be, for example, an instruction to trigger an alarm or activate lighting installed on the premises, or an instruction to directly notify a person responsible for the premises via mobile telecommunications links or the like, etc. Processing section 1101 in main section 1100 may permit identification of the detected target by an internally contained, complex detection device (using deep learning or a similar technique).Alternatively, such a complex detection device can be provided externally, in which case the complex detection device can be connected via the telecommunications links 1300.

[0409] A related technique is described in the specification of US patent no. US 7 425 983 B2.

[0410] Another embodiment of such a security monitoring system could be a personnel monitoring system to be installed at a gate in an airport, a barrier at a train station, a building entrance, or the like. The object being monitored by such a personnel monitoring system could, for example, be a gate in an airport, a barrier at a train station, a building entrance, or the like.

[0411] If the object being monitored is a gate at an airport, the sensor section(s) 1010 may, for example, be installed in a personal belongings screening system at the gate. In this case, there are two possible screening procedures. In the first procedure, the millimeter-wave radar transmits an electromagnetic wave and receives the electromagnetic wave reflected by a passenger (who is the object being monitored), thus screening the passenger's personal belongings or similar items. In the second procedure, the antenna receives a weak millimeter wave emitted by the passenger's body, thus screening for any foreign objects the passenger might be concealing. In the latter procedure, the millimeter-wave radar primarily scans the received millimeter wave.This scanning function can be implemented using digital beamforming or a mechanical scanning process. It is noted that the processing by main section 1100 can utilize a communication process and a recognition process similar to those in the examples described above. (Building inspection system (non-destructive testing))

[0412] A fourth monitoring system is a system that monitors or inspects the concrete material of a road, railway overpass, building, etc., or the interior of a road or the ground, etc. (hereinafter referred to as the "building inspection system"). The object of monitoring by this building inspection system may be, for example, the interior of the concrete material of an overpass or building, etc., or the interior of a road or the ground, etc.

[0413] If the monitored object is the interior of a concrete building, the sensor section 1010 is configured, for example, so that the antenna 1011 can perform scanning movements along the surface of the concrete building. As used here, these scanning movements can be implemented manually, or a separate fixed rail can be provided for the scanning movement, along which the movement can be effected by the driving force from an electric motor or the like. In the case that the monitored object is a road or the ground, the antenna 1011 can be mounted face down on a vehicle or the like, and the vehicle can be driven at a constant speed, thereby generating a scanning movement. The electromagnetic wave to be used by the sensor section 1010 can be a millimeter wave, for example, in the so-called terahertz region, which exceeds 100 GHz.As previously described, even with an electromagnetic wave frequency exceeding, for example, 100 GHz, an array antenna according to one embodiment of the present disclosure can be adapted to exhibit lower losses than conventional patch antennas or the like. A higher-frequency electromagnetic wave is able to penetrate deeper into the object being inspected, such as concrete, thereby enabling a more accurate non-destructive examination. It is noted that the processing by main section 1100 can also utilize a communication process and a detection process similar to those in the other monitoring systems described above.

[0414] A related technique is described in the specification of US patent no. US 6 661367 B2. (Personal monitoring system)

[0415] A fifth monitoring system is a system that guards a person receiving care (hereinafter referred to as a "personal monitoring system"). The person being monitored by this personal monitoring system could be, for example, a person receiving care or a patient in a hospital, etc.

[0416] If the person being monitored is a care recipient in a room of a care facility, the sensor section(s) 1010, for example, is / are placed at one or two or more positions in the room, enabling it to monitor the entire interior of the room. In this case, the sensor section 1010 may also include an optical sensor, such as a camera, in addition to the millimeter-wave radar. This allows the person being monitored to be observed from multiple perspectives through a combined process based on radar and image information. Conversely, if the person being monitored is a person, monitoring with a camera or similar device may be inappropriate from a data protection perspective. Therefore, the selection of sensors must take this aspect into account.It is noted that target detection using millimeter-wave radar allows a person being monitored to be detected not by their image, but by a signal (which is, in a sense, a shadow of the person). Therefore, millimeter-wave radar can be considered a sensor with advantages from a data protection perspective.

[0417] Information about the care recipient, obtained by sensor section(s) 1010, is sent to main section 1100 via telecommunications links 1300. Main section 1100 gathers other information (e.g., reference data or the like, required for the correct recognition of the care recipient's target information) that may be needed in a more complex recognition process or control, and issues necessary control instructions or the like based on this information. As used here, a necessary control instruction might be, for example, an instruction to directly notify a responsible party based on the detection result, etc. Processing section 1101 within main section 1100 may allow for the recognition of the detected target by an internally contained, complex recognition device (using deep learning or a similar technique).Alternatively, such a complex detection device can be provided externally, in which case the complex detection device can be connected via the telecommunications links 1300.

[0418] In the case that the object being monitored by the millimeter wave radar is a person, at least the following two functions can be added.

[0419] One primary function is monitoring heart rate and / or respiratory rate. In millimeter-wave radar, an electromagnetic wave is capable of penetrating clothing to detect the position and movements of a person's skin surface. First, the processing unit 1101 detects the person being monitored and their external form. Next, in the case of heart rate detection, for example, a location on the body surface where heartbeats are easily detectable can be identified, and these movements can be tracked chronologically. This allows, for instance, the detection of a heart rate per minute. The same applies to respiratory rate detection.Using this function allows the health status of a person receiving care to be constantly monitored, enabling higher-quality care for that person.

[0420] A second function is fall detection. A person receiving care, such as an elderly person, may fall from time to time due to weakness in their legs and feet. When a person falls, the speed or acceleration of a specific part of the person's body, for example, the head, reaches or exceeds a certain level. If the subject of the millimeter-wave radar is a person, the relative speed or acceleration of the target of interest can be continuously detected. Therefore, for example, by identifying the head as the subject of the surveillance and chronologically detecting its relative speed or acceleration, a fall can be detected when a speed of or above a certain value is recorded.Upon detecting a fall, processing section 1101 can issue an instruction or similar, such as relevant nursing assistance.

[0421] It is noted that the sensor section(s) 1010 in the monitoring system described above, or the like, are attached to a fixed position. However, the sensor section(s) 1010 can also be installed on a moving object, such as a robot, a vehicle, or a flying object like a drone. As used here, the vehicle or the like can include not only a motor vehicle but also, for example, a smaller moving object such as an electric wheelchair. In this case, this moving object can have an internal GPS unit with which its current position can be confirmed at any time.Additionally, this moving object can also have the function of further improving the accuracy of its own current position by using map information and the map update information described with reference to the aforementioned fifth processing unit.

[0422] Furthermore, in any device or system similar to the first to third detection devices, first to sixth processing devices, first to fifth monitoring systems, etc., described above, the same design can be used to utilize an array antenna or millimeter-wave radar according to an embodiment of the present disclosure. <Anwendungsbeispiel 3: Kommunikationssystem> (First example of a communication system)

[0423] The waveguide and antenna device (array antenna) according to the present disclosure can be used for the transmitter and / or receiver with which a communication system (telecommunication system) is constructed. The waveguide and antenna device according to the present disclosure are formed from layered conductive elements and are therefore able to keep the size of the transmitter and / or receiver smaller than when using a hollow waveguide. In addition, a dielectric is not necessary, and thus the dielectric loss of electromagnetic waves can be kept lower than when using a microstrip line. Therefore, a communication system can be constructed that includes a small and highly efficient transmitter and / or receiver.

[0424] Such a communication system can be analog, sending or receiving an analog signal that is directly modulated. However, a digital communication system can be used to construct a more flexible and powerful communication system.

[0425] The following refers to Fig. 42 a digital communication system 800A is described in which a waveguide device and an antenna device are used according to an embodiment of the present disclosure.

[0426] Fig. Figure 42 is a block diagram showing a design for the digital communication system 800A. The communication system 800A comprises a transmitter 810A and a receiver 820A. The transmitter 810A comprises an analog-to-digital (A / D) converter 812, an encoder 813, a modulator 814, and a transmitting antenna 815. The receiver 820A comprises a receiving antenna 825, a demodulator 824, a decoder 823, and a digital-to-analog (D / A) converter 822. At least either the transmitting antenna 815 or the receiving antenna 825 can be implemented using an array antenna according to one embodiment of the present disclosure. In this application example, the circuits comprising the modulator 814, the encoder 813, the A / D converter 812, and so on, which are connected to the transmitting antenna 815, are referred to as the transmitting circuit.The circuits comprising the demodulator 824, the decoder 823, the D / A converter 822, and so on, which are connected to the receiving antenna 825, are referred to as the receiving circuit. The transmitting circuit and the receiving circuit together can be called the communication circuit.

[0427] The transmitter 810A uses the analog-to-digital (A / D) converter 812 to convert an analog signal received from the signal source 811 into a digital signal. Next, the digital signal is encoded by the encoder 813. As used here, "encoding" means changing the digital signal to be transmitted into a format suitable for communication. Examples of such encoding include CDM (code-division multiplexing) and the like. Furthermore, any conversion to achieve TDM (time-division multiplexing), FDM (frequency-division multiplexing), or OFDM (orthogonal frequency-division multiplexing) is also an example of encoding. The encoded signal is converted by the modulator 814 into a radio-frequency signal for transmission from the transmitting antenna 815.

[0428] In the field of communications, a wave representing a signal to be superimposed onto a carrier wave can be called a "signal wave"; however, the term "signal wave" as used in this specification does not have this definition. A "signal wave" according to this specification, in a broad sense, means any electromagnetic wave intended to propagate in a waveguide or any electromagnetic wave intended to transmit / receive via an antenna element.

[0429] The receiver 820A converts the high-frequency signal received by the receiving antenna 825 into a low-frequency signal at the demodulator 824 and into a digital signal at the decoder 823. The decoded digital signal is converted back into an analog signal by the digital-to-analog (D / A) converter 822 and sent to a data sink (data receiver) 821. The above processes complete a sequence of transmitting and receiving operations.

[0430] If the communicating unit is a digital device such as a computer, the analog-to-digital conversion of the transmitted signal and the digital-to-analog conversion of the received signal are not necessary in the processes described above. Therefore, the 812 analog-to-digital converter and the 822 digital-to-analog converter can be used in Fig. 42 can be omitted. A system with such a design is also included in the digital communication system.

[0431] Various methods can be used in a digital communication system to ensure signal intensity or to increase channel capacity. Many of these methods are also effective in a communication system that uses radio waves in the millimeter wave or terahertz band.

[0432] Radio waves in the millimeter or terahertz band have a higher degree of directness than radio waves of lower frequencies and are subject to less diffraction, meaning they are less likely to be deflected by an obstacle. Therefore, it is not uncommon for a receiver to not directly receive a radio wave transmitted from a transmitter. Even in such situations, reflected waves can often be received; however, a reflected wave of a radio signal is frequently of lower quality than the direct wave, making stable reception more difficult. Furthermore, a multitude of reflected waves can arrive via different paths. In this case, the received waves with different path lengths could be out of phase with each other, causing multipath loss.

[0433] One technique for improving such situations is antenna diversity. In this technique, at least either the transmitter or the receiver has a multitude of antennas. If these multiple antennas are separated by distances differing by at least approximately one wavelength, the resulting states of the received waves will vary. Accordingly, the antenna capable of transmitting / receiving with the highest quality is selectively used, thus improving communication reliability. Alternatively, signals received from more than one antenna can be combined to improve signal quality.

[0434] At the in Fig. In the communication system 800A shown in Figure 42, the receiver 820A can, for example, have a plurality of receiving antennas 825. In this case, a switching device exists between the plurality of receiving antennas 825 and the demodulator 824. Through the switching device, the receiver 820A connects the antenna from the plurality of receiving antennas 825 that provides the signal with the highest quality to the demodulator 824. In this case, the transmitter 810A can also have a plurality of transmitting antennas 815. (Second example of a communication system)

[0435] Fig. Figure 43 is a block diagram showing an example of a communication system 800B, which includes a transmitter 810B capable of varying the radiation pattern of radio waves. In this application example, the receiver is identical to the one shown in Figure 43. Fig. 42 receiver 820A shown; therefore, the receiver in the illustration is in Fig. 43 omitted. In addition to the construction of transmitter 810A, transmitter 810B also includes an antenna array 815b comprising a plurality of antenna elements 8151. The antenna array 815b can be an array antenna according to one embodiment of the present disclosure. Transmitter 810B further comprises a plurality of phase shifters (PS) 816, each connected between modulator 814 and the plurality of antenna elements 8151. In transmitter 810B, an output of modulator 814 is sent to the plurality of phase shifters 816, where phase differences are introduced and the resulting signals are routed to the plurality of antenna elements 8151.In the case that the plurality of antenna elements 8151 are arranged at equal intervals, a main lobe 817 of the antenna array 815b, when a radio frequency signal whose phase differs by a certain amount with respect to an adjacent antenna element is fed into each antenna element 8151, is aligned in an azimuth that is inclined from the front, this inclination corresponding to the phase difference. This process can be called beamforming.

[0436] The azimuth of the main lobe 817 can be changed by allowing the respective phase shifters 816 to introduce varying phase differences. This process can be described as beam steering. By finding phase differences that are conducive to the best transmit / receive conditions, the reliability of the communication can be increased. Although the present example illustrates a case in which the phase difference to be introduced by the phase shifters 816 is constant between each adjacent antenna element 8151, this is not a limitation. Furthermore, phase differences can be introduced in such a way that the radio wave is radiated in an azimuth that allows not only the direct wave but also reflected waves to reach the receiver.

[0437] A technique called zero-control can also be used in the 810B transmitter. This technique involves adjusting phase differences to create a state in which the radio wave is not radiated in any specific direction. Zero-control makes it possible to restrict the transmission of radio waves toward any other receiver to which the radio wave is not intended, thus preventing interference. Although a very wide frequency band is available for digital communication using millimeter or terahertz waves, it is still preferable to use the bandwidth as efficiently as possible. By using zero-control, multiple instances of transmitting / receiving can be performed within the same band, thereby increasing bandwidth utilization.A method that increases bandwidth utilization by using techniques such as beamforming, beam steering, and zero control can sometimes be referred to as SDMA (multiple access with spatial division). (Third example of a communication system)

[0438] To increase channel capacity in a specific frequency band, a method called MIMO (Multiple Input and Multiple Output) can be used. MIMO employs multiple transmitting antennas and multiple receiving antennas. Each transmitting antenna emits a radio wave. In one example, different signals can be superimposed on the emitted radio wa...

Claims

Slotted antenna device comprising: a first electrically conductive component (110) with a first electrically conductive surface (110b) on a front side and a second electrically conductive surface (110a) on a rear side and with at least one slot (112) extending from the first electrically conductive surface (110b) to the second electrically conductive surface (110a); a second electrically conductive component (120) on the rear side of the first electrically conductive component (110), wherein the second electrically conductive component (120) has a third electrically conductive surface (120a) on the front side, the third electrically conductive surface (120a) being opposite to the second electrically conductive surface (110a);a rib-shaped waveguide element (122) on the second electrically conductive surface (110a) of the first electrically conductive element (110), wherein the waveguide element (122) has an electrically conductive waveguide surface (122a) that is opposite to the third electrically conductive surface (120a) and extends along the third electrically conductive surface (120a); and an artificial magnetic conductor on at least either the second electrically conductive surface (110a) or the third electrically conductive surface (120a), wherein the artificial magnetic conductor extends on both sides of the waveguide element (122), wherein the third electrically conductive surface (120a), the waveguide surface (122a) and the artificial magnetic conductor define a waveguide in an intermediate space extending between the third electrically conductive surface (120a) and the waveguide surface (122a);the waveguide element (122) has a first rib (122A) and a second rib (122B); one end of the first rib (122A) and one end of the second rib (122B) are opposite to each other; viewed from a direction perpendicular to the waveguide surface (122a), at least one slot (112) is arranged between one end of the first rib (122A) and one end of the second rib (122B); the at least one slot (112) is open through the first electrically conductive surface (110b) to an external space; and at least either a spacing between the third electrically conductive surface (120a) and the waveguide surface (122a) or a width of the waveguide surface (122a) varies along a direction in which the waveguide element (122) extends. Slotted antenna device according to claim 1, wherein at least either the second electrically conductive component (120) or the waveguide component (122) has: at least a recess (122d) which serves to widen the distance between the third electrically conductive surface (120a) and the waveguide surface (122a) relative to any adjacent point; or at least a protrusion (122b) which serves to narrow the distance between the third electrically conductive surface (120a) and the waveguide surface (122a) relative to any adjacent point. Slotted antenna device according to claim 1 or 2, wherein the waveguide element (122) comprises: at least one wide section (122e) serving to widen the width of the waveguide area (122a) relative to any adjacent point; or at least one narrow section (122f) serving to narrow the width of the waveguide area (122a) relative to any adjacent point. Slotted antenna device according to one of claims 1 to 3, wherein the first electrically conductive component (110) has a plurality of slots (112) including the at least one slot, the plurality of slots being arranged along the direction in which the waveguide component (122) extends; the waveguide component (122) having a plurality of ribs including the first rib (122A) and the second rib (122B); and viewed from a direction perpendicular to the waveguide surface (122a), each of the plurality of slots is arranged between the opposite ends (122c, 122c) of two adjacent ribs from the plurality of ribs; and each of the plurality of slots is open through the first electrically conductive surface (110b) to the outside space. Slotted antenna device according to one of claims 1 to 4, comprising a plurality of rib-shaped waveguide elements (122) including the waveguide element, wherein the plurality of waveguide elements (122) is on the second electrically conductive surface (110a); the first electrically conductive element (110) has a plurality of slots (112) including the at least one slot (112), wherein the plurality of slots (112) is arranged along a direction which intersects the direction in which the waveguide element (122) extends; each of the plurality of waveguide elements (122) has a plurality of ribs such that the ends of two adjacent ribs from the plurality of ribs are opposite to each other;Viewed from a direction perpendicular to the waveguide surfaces (122a) of the plurality of waveguide elements, each of the plurality of slots (112) is arranged between the ends of two adjacent of the plurality of ribs; and each of the plurality of slots (112) is open through the first electrically conductive surface (110b) to the external space. Slotted antenna device according to one of claims 1 to 5, wherein the artificial magnetic conductor has a plurality of electrically conductive rods (124) on the second electrically conductive surface (110a) and each of the plurality of electrically conductive rods (124) has a leading end (124a) opposite to the third electrically conductive surface (120a) and a root (124b) connected to the second electrically conductive surface. Slotted antenna device according to any one of claims 1 to 5, wherein the artificial magnetic conductor has a plurality of electrically conductive bars (124) on the second electrically conductive surface (110a) and a length of the second rib (122B), measured along the direction in which the waveguide element (122) extends, is approximately equal to or greater than λ0 / 16 and approximately equal to or less than λ0 / 4, wherein λ0 is a wavelength of an electromagnetic wave in free space corresponding to a medium frequency in an operating frequency band, which is either transmitted or received by the slotted antenna device. Slotted antenna device according to any one of claims 1 to 5, wherein at least either the second electrically conductive component (120) or the waveguide component (122) has a plurality of recesses serving to widen the spacing between the third electrically conductive surface (120a) and the waveguide surface (122a) relative to any adjacent location; the plurality of recesses comprises a first recess (122d1), a second recess (122d2) and a third recess (122d3) which are adjacent to each other and follow one another along the direction in which the waveguide component (122) extends; and a distance between the centers of the first recess (122d1) and the second recess (122d2) differs from a distance between the centers of the second recess (122d2) and the third recess (122d3). Slotted antenna device according to any one of claims 1 to 5, wherein the waveguide element (122) has a plurality of wide sections which serve to widen the width of the waveguide area (122d) relative to any adjacent point; the plurality of wide sections comprises a first wide section, a second wide section and a third wide section which are adjacent to each other and follow one another along the direction in which the waveguide element (122) extends; and a distance between the centers of the first wide section and the second wide section differs from a distance between the centers of the second wide section and the third wide section. Slotted antenna device according to claim 4 or 5, wherein at least either the spacing between the third electrically conductive surface (120a) and the waveguide surface (122a) or the width of the waveguide surface (122a) along the direction in which the waveguide element (122) extends is varied with a period equal to or greater than 1 / 2 of a distance between the centers of two adjacent slots (112, 112) from the plurality of slots. Slotted antenna device according to claim 4 or 5, wherein the slotted antenna device is used at least either for transmitting or receiving an electromagnetic wave of a band with a central wavelength λo in free space; the width of the waveguide surface (122a) is smaller than λo; at least either the second electrically conductive component (120) or the waveguide component (122) has a plurality of additional elements which at least either change the spacing between the third electrically conductive surface (120a) and the waveguide surface (122a) or the width of the waveguide surface (122a) relative to any adjacent point;and at least either the spacing between the third electrically conductive surface (120a) and the waveguide surface (122a) or the width of the waveguide surface (122a) along the direction in which the waveguide element (122) extends is varied with a period longer than λR / 4, where λ is the pure wavelength of an electromagnetic wave with wavelength λ0 when propagating in a waveguide without the plurality of additional elements, the waveguide extending between the electrically conductive element and the waveguide element. Slot antenna device according to one of claims 1 to 11, wherein the first electrically conductive surface (110b) of the first electrically conductive component (110) has a shape that defines at least one horn (114) that communicates with the at least one slot (112). Radar device comprising: the slotted antenna device according to any one of claims 1 to 12 and either one or both of a transmitter and a receiver connected to the slotted antenna device, wherein one or both of the transmitter and the receiver are implemented as an integrated millimeter wave circuit. Radar system (510) comprising: the slot antenna device according to any one of claims 1 to 12; either one or both of a transmitter and a receiver connected to the slot antenna device; either one or both of an analog-to-digital (A / D) converter connected to the receiver and a digital-to-analog (D / A) converter connected to the transmitter; and a signal processing circuit (560) connected to one or both of the analog-to-digital converters and the digital-to-analog converter; wherein one or both of the transmitter and the receiver are implemented as an integrated millimeter-wave circuit; and the signal processing circuit performs at least either an incidence direction estimation or a distance estimation. Communication system comprising: the slot antenna device according to any one of claims 1 to 12; either one or both of a transmitter and a receiver connected to the slot antenna device; either one or both of an analog-to-digital (A / D) converter connected to the receiver and a digital-to-analog (D / A) converter connected to the transmitter; and a signal processing circuit (560) connected to one or both of the analog-to-digital converter and the digital-to-analog converter; wherein the signal processing circuit performs at least either encoding a digital signal or decoding a digital signal.

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