ANTENNA DEVICE

Abstract

Antenna device, comprising: a plurality of transmitting antennas (21 to 23, 21a to 23a) aligned at a reference distance along an orientation direction, wherein the reference distance and the orientation direction are specified; a first receiving antenna (26, 26a) with an aperture width in the direction of orientation that is fixed to a first width that is smaller than the reference distance; and a plurality of second receiving antennas (24, 25, 24a, 25a), each having an aperture width in the direction of orientation which is fixed to a second width which is less than or equal to the first width, wherein the plurality of second receiving antennas is aligned at a distance which is less than the reference distance along the direction of orientation, wherein a distance along the direction of alignment between a phase center of the first receiving antenna and a phase center of a second receiving antenna, which is closest to the first receiving antenna among the plurality of second receiving antennas, is fixed to a length greater than or equal to a value obtained by multiplying the reference distance by a value obtained by subtracting 1 from the total number of transmitting antennas.

Description

[Cross-reference to related registration]

[0001] This international application is based on and claims the priority benefit of Japanese patent application No. 2017-249088, which was filed with the Japanese Patent Office on December 26, 2017, and the entire disclosure of Japanese patent application No. 2017-249088 is incorporated herein by reference. [Technical field]

[0002] The invention relates to an antenna device that implements several types of array antennas with different receiving antenna spacings. [State of the art]

[0003] The publication (PTL) 1 cited below discloses a technique for arranging two transmitting antennas at separate positions and a plurality of receiving antennas between these transmitting antennas in order to provide twice as many channels as the number of receiving antennas in a small area. It is noted that the channel represents a path along which signals from one of the transmitting antennas reach one of the receiving antennas by being reflected from an object to be detected. [Citation list][Printed state of the art]

[0004] [Printed Publication 1] JP 2011-526371 A [Brief description of the invention]

[0005] However, as a result of in-depth investigations carried out by the inventor, it has been found that the known technology disclosed in Publication 1 has the following problem.

[0006] Specifically, with the known technology, for example, in the case where both a receiving antenna distance for accurately detecting the direction of an object at a narrow angle and a receiving antenna distance for detecting the object at a wide angle must be achieved, two types of antenna devices, in which receiving antennas are arranged at different distances, must be prepared individually, which leads to a problem of increasing the size of the device.

[0007] One aspect of the invention is to provide an antenna device that implements several types of array antennas with different receiving antenna spacings using a simple configuration.

[0008] An antenna device according to one aspect of the invention comprises a plurality of transmitting antennas, a first receiving antenna and a plurality of second receiving antennas.

[0009] The multiple transmitting antennas are aligned at a predetermined reference distance along a predetermined direction of orientation. The aperture width of the first receiving antenna in the direction of orientation is set to a first width that is smaller than the reference distance. The multiple second receiving antennas each have an aperture width in the direction of orientation that is set to a second width that is less than or equal to the first width, and are aligned along the direction of orientation at a distance that is smaller than the reference distance.The distance along the direction of alignment between the center position of the first receiving antenna and the phase center of a second receiving antenna, which is closest to the first receiving antenna among the multitude of second receiving antennas, is set to a length greater than or equal to a value obtained by multiplying the reference distance by a value obtained by subtracting 1 from the number of transmitting antennas.

[0010] With such a configuration, various directivity patterns can be provided using a virtual array or group of virtual receiving antennas formed from the plurality of transmitting antennas and the first receiving antenna, and a virtual array or group of virtual receiving antennas formed from the plurality of transmitting antennas and the plurality of second receiving antennas. It is noted that the antennas in the first virtual group are arranged at a relatively small distance, and the antennas in the latter virtual group are arranged at a relatively large distance. In other words, two types of virtual arrays with different grid lobes can be implemented in essentially the same device size as that of known technology. [Brief description of the drawings] Fig. Figure 1 is a block diagram showing the configuration of a radar device to which an antenna device is applied. Fig. Figure 2 is an explanatory diagram showing the arrangement of antennas in an antenna device according to the first embodiment. Fig. Figure 3 is a structure diagram showing a specific example of transmitting antennas and receiving antennas. Fig. Figure 4 is an explanatory diagram showing a relationship between a target and the transmitting and receiving antennas. Fig. Figure 5 is an explanatory diagram showing the arrangement of virtual receiving antennas in a virtual array. Fig. Figure 6 is an explanatory diagram showing the arrangement of a virtual array implemented in the antenna device. Fig. Figure 7 is an explanatory diagram showing an MRR array, which is a virtual array used in a midrange mode. Fig. Figure 8 is an explanatory diagram showing an LRR array, which is a virtual array used in a far-range mode. Fig. Figure 9 is an explanatory diagram showing a vertical array, which is a virtual array used in a vertical angle measurement mode. Fig. Figure 10 is a flowchart of a target capture process performed by a processing unit. Fig. Figure 11 is an explanatory diagram showing the arrangement of antennas in an antenna device according to the second embodiment. Fig. Figure 12 is an explanatory diagram showing the arrangement of a virtual array implemented in the antenna device. Fig. Figure 13 is an explanatory diagram showing an MRR array, which is a virtual array used in midrange mode. Fig. Figure 14 is an explanatory diagram showing an LRR array, which is a virtual array used in the far-range mode. Fig. Figure 15 is an explanatory diagram showing a vertical array, which is a virtual array used in the vertical angle measurement mode. [Description of the embodiments]

[0011] The following are descriptions of embodiments according to the invention with reference to the drawings. [1. First embodiment][1-1. Configuration]

[0012] A radar device 1 according to the first embodiment, shown in Fig. Radar device 1 is installed and used in a vehicle to detect various objects located around the vehicle. Radar device 1 is a MIMO radar, which transmits and receives radio waves simultaneously using multiple antennas. MIMO stands for Multi-Input Multi-Output.

[0013] The radar device 1 includes an antenna device 2 according to the present embodiment. The radar device 1 may further include a transmit / receive unit 3 and a processing unit 4. [1-1-1. Antenna device]

[0014] As in Fig. As shown in Figure 2, the antenna device 2 comprises three transmitting antennas 21 to 23 and four receiving antennas 24 to 27. The number of transmitting antennas and the number of receiving antennas are not limited to these numbers; it is sufficient that at least two transmitting antennas and at least two receiving antennas are provided. Each of the antennas 21 to 27 is provided using a copper foil structure, which is formed, for example, on a dielectric substrate.

[0015] As in Fig. As shown in Figure 2, three transmitting antennas 21 to 23 are arranged in a single line along a predetermined orientation direction at a predetermined reference distance D. This orientation direction is referred to below as the x-axis direction, and any direction orthogonal to it is referred to as the y-axis direction. The transmitting antennas 21 to 23 have the same shape and size.

[0016] The aperture widths or opening widths of the four receiving antennas 24 to 27 in the y-axis direction are the same.

[0017] The aperture widths of the two receiving antennas 26, 27 in the x-axis direction are each set to a first width W1, which is smaller than the reference distance D. The receiving antenna 27 is arranged at a position defined by moving the receiving antenna 26 by the reference distance D in the x-axis direction and further by a predetermined vertical distance V in the y-axis direction.

[0018] The aperture widths of the two other receiving antennas 24, 25 in the x-axis direction are each set to a second width W2, which is smaller than the first width W1. The receiving antenna 25 is positioned by moving the receiving antenna 24 by a predetermined distance d in the x-axis direction. The second width W2 and the distance d are set such that the circumscribed geometric shape of the two receiving antennas 24, 25 has the same shape and size as each of the receiving antennas 26, 27. In other words, the aperture widths of a combined antenna formed from two receiving antennas 24, 25 (hereinafter referred to as the combined antenna 24-25) in the x-axis and y-axis directions are the same as those of each of the other two receiving antennas 26, 27.

[0019] The receiving antenna 26 is arranged at a position defined by moving the combined antenna 24-25 in the x-axis direction by a distance 3D obtained by multiplying the reference distance D by the number of transmitting antennas.

[0020] The transmitting antennas 21 to 23 are arranged at positions defined by shifting the receiving antennas 24 to 27 in the y-axis direction such that they do not overlap any of the receiving antennas 24 to 27. Furthermore, the transmitting antennas 21 to 23 are arranged such that the position of the phase center of each of the transmitting antennas 21 to 23 lies in the x-axis direction between the phase center of receiving antenna 25 and the phase center of receiving antenna 26. This means that the distance between the phase center of receiving antenna 25 and the phase center of receiving antenna 26 is defined as greater than 2D.

[0021] It is noted that the phase center is a point of incoming or outgoing radio waves, which is practically considered a concentration point of the radio waves. In the case where an antenna has a vertically and horizontally symmetrical shape, such as a rectangle or a circle, the phase center essentially coincides with the position of the antenna's center of gravity.

[0022] Below is a specific example of each of the transmitting antennas 21 to 23 and the receiving antennas 24 to 27 with reference to Fig. As described in Figure 3, the transmitting antennas 21 to 23 and the receiving antennas 24, 25, each having an aperture width in the x-axis direction defined as the second width W2, include a plurality of patch antennas P arranged in a single line along the y-axis direction and a power supply line L designed to energize the patch antennas in the same phase. The receiving antennas 26, 27, each having an aperture width in the x-axis direction defined as the first width W1, are configured in which the patch antennas P are arranged in two lines and power supply lines L are connected to both of the two lines of the patch antennas P. [1-1-2. Virtual Array]

[0023] With reference to Fig. 4 and Fig. Section 5 describes a virtual array or arrangement of M × N antennas, including M transmitting antennas and N receiving antennas. As in Fig. As shown in Figure 4, in the case where M equals 2 and N equals 2, there are two transmitting antennas TX1, TX2 at a first distance d. T and two receiving antennas RX1, RX2 at a second distance d R arranged.

[0024] Assume that an object to be detected is located in a direction at an angle θ ahead of the transmitting antennas TX1, TX2 and the receiving antennas RX1, RX2. The reflection coefficient through the object is denoted by R, and a change in the phase of a signal along a path from TX1 to the object is denoted by α. T denoted, and a change in the phase of a signal in a path from the object to RX1 is denoted by α R designated. It is noted that α T and α Rrepresented by complex numbers.

[0025] In this case, a signal sent by TX1 and received by RX1 is represented by expression (1). A signal sent by TX1 and received by RX2 is represented by expression (2). A signal sent by TX2 and received by RX1 is represented by expression (3). A signal sent by TX2 and received by RX2 is represented by expression (4). [Expression 1] αT⋅R⋅αR αT⋅R⋅αR⋅exp(jkdRsinθ) αT⋅R⋅αR⋅exp(jkdTsinθ) αT⋅R⋅αR⋅exp(jk(dT+dR)sinθ)

[0026] As in Fig. As shown in Figure 5, these expressions are equivalent to those in the case where a signal transmitted by a transmitting antenna is received by four receiving antennas spaced at respective intervals d R , d T and d T + d Rare arranged. The virtual receiving antennas arranged in this way are referred to as a virtual array or a virtual arrangement.

[0027] In other words, as in Fig. As shown in Figure 6, in antenna device 2 the combination of the three transmitting antennas 21 to 23 and the four receiving antennas 24 to 27 is represented as a virtual array with 12 virtual receiving antennas. Specifically, virtual receiving antennas are represented by the dashed lines in Figure 6. Fig. 6 are represented, formed at positions that are determined by moving the four receiving antennas 24 to 27, which are defined by the solid lines in Fig. 6 are represented to define a distance D and a distance 2D in the x-axis direction.

[0028] Hereinafter, receiving antennas 24 and 25 are referred to as channels CH1 and CH2, virtual receiving antennas located at positions defined by shifting receiving antennas 24 and 25 by a distance D are referred to as channels CH3 and CH4, and virtual receiving antennas located at positions defined by further shifting receiving antennas 24 and 25 by a distance D are referred to as channels CH5 and CH6. Furthermore, receiving antenna 26 is referred to as channel CH7, a virtual receiving antenna located at a position defined by shifting receiving antenna 26 by a distance D is referred to as channel CH8, and a virtual receiving antenna located at a position defined by further shifting receiving antenna 26 by a distance D is referred to as channel CH9.Furthermore, the receiving antenna 27 is designated as channel CH10, a virtual receiving antenna located at a position defined by moving the receiving antenna 27 by a distance D is designated as channel CH11, and a virtual receiving antenna located at a position defined by a further movement of the receiving antenna 27 by a distance D is designated as channel CH12. It is noted that the receiving antenna 26 corresponds to a first receiving antenna, the receiving antennas 24 and 25 correspond to a second receiving antenna, and the receiving antenna 27 corresponds to an additional receiving antenna.

[0029] As in Fig. As shown in Figure 7, the channels CH1 to CH6 form a uniformly spaced 6-element array (hereinafter referred to as an MRR array) in which the channels are arranged at a distance d in the x-axis direction.

[0030] The combined antenna formed from the pair of channels CH1 and CH2, the combined antenna formed from the pair of channels CH3 and CH4, and the combined antenna formed from the pair of channels CH5 and CH6 are referred to as a channel CH1-2, a channel CH3-4, and a channel CH5-6, respectively. As in Fig. As shown in Figure 8, the channels CH1-2, CH3-4, CH5-6 and CH7 to CH9 form an evenly spaced 6-element array (hereinafter referred to as an LRR array) in which the channels are arranged at a distance D in the x-axis direction.

[0031] As in Fig. As shown in Figure 9, the pair of channels CH8 and CH10 and the pair of channels CH9 and CH11 each form a 2-element array (hereinafter referred to as a vertical array) in which the channels are arranged at a distance V in the y-axis direction. [1-2. Transmit / Receive Unit]

[0032] The transmit / receive unit 3 delivers transmission signals to the respective transmit antennas 21 to 23. The transmit / receive unit 3 modulates each of the transmission signals using a Doppler Division Multiple Access (DDMA) technique. DDMA is a modulation method that allows the identification of individual signals from received signals on which two or more signals, simultaneously transmitted by two or more transmit antennas, are superimposed. DDMA is a technique used, for example, in MIMO radar.

[0033] The transmit / receive unit 3 generates a beat signal for each of the receiving antennas 24 to 27 by mixing a local signal, which is a transmit signal serving as a reference among the transmit signals described above, into each of the received signals supplied by the respective receiving antennas 24 to 27 and then feeding the beat signal to the processing unit 4. [1-3. Processing unit]

[0034] The processing unit 4 comprises a microcomputer with a central processing unit (CPU) 41 and a semiconductor memory (hereinafter referred to as a memory 42), such as random-access memory (RAM) or ROM. Each function of the processing unit 4 is implemented by the CPU 41, which executes a program stored on a non-volatile, physical recording medium. In this example, the memory 42 corresponds to the non-volatile, physical recording medium on which the program is stored. Furthermore, a procedure corresponding to the program is performed during the execution of this program. It is noted that the processing unit 4 can comprise a single microcomputer, or two or more microcomputers.

[0035] Processing Unit 4 performs at least one target acquisition process. The method for implementing each function of Processing Unit 4 is not limited to a method using software; some or all of the functions of Processing Unit 4 may be implemented using one or more hardware products. For example, if a function is implemented using an electronic circuit, which is a hardware product, the electronic circuit may be a digital circuit, an analog circuit, or a combination of these. [1-4. Processing]

[0036] Next, the target capture process, which is carried out by processing unit 4, will be described with reference to the flowchart in Fig. 10 described. When processing unit 4 is activated, the target acquisition process is carried out periodically.

[0037] First, the processing unit 4 in S110 performs a radar measurement by operating the transmit / receive unit 3 and receiving sample data of the beat signal supplied by each of the receiving antennas 24 to 27.

[0038] In S120, processing unit 4 extracts signals from 12 channels in the virtual array based on the sample data obtained in S110. Specifically, a fast Fourier transform (FFT) or similar is performed for each of the receiving antennas 24 to 27, and a Doppler spectrum is calculated that represents the Doppler frequency components contained in the received signals. In other words, since the transmitted signals resulting from DDMA modulation have different phase shifts for the respective transmitting antennas, the transmitted signals from the respective transmitting antennas are extracted as signal components with different Doppler frequencies on a Doppler spectrum. Consequently, signals from channels CH1, CH3, and CH5 are extracted from the signals received by receiving antenna 24. Signals from channels CH2, CH4, and CH6 are extracted from the signals received by receiving antenna 25.Signals from channels CH7 to CH9 are extracted from the signals received by receiving antenna 26. Signals from channels CH10 to CH12 are extracted from the signals received by receiving antenna 27.

[0039] In S130, processing unit 4 performs a process in a medium-range radar (MRR) mode. In the MRR mode process, the signals from channels CH1 to CH6, which correspond to the... Fig. The 7 MRR array shown includes a target located in a mid-range or wide-angle area, detected, for example, by a digital beamforming (hereinafter DBF) method or the like.

[0040] In S140, processing unit 4 performs a process in long-range radar (LRR) mode. In the LRR mode process, the signals from the combined channels CH1-2, CH3-4, and CH5-6, as well as channels CH7 to CH9, which are part of the... Fig. The LRR array shown in Figure 8 includes a target located in a far, narrow-angled region, detected, for example, by a multiple storage, integration, and correlation (MUSIC) method or similar. It is noted that in the LRR mode process, the result of the MRR mode process can be used, for example, to perform a process for determining the direction to the target, which is made uncertain by a grid.

[0041] In S150, processing unit 4 performs a process in a vertical angle measurement mode. This process uses signals from at least one of the channel pairs CH8 and CH10 and the channel pair CH9 and CH11, which are part of the... Fig. The data from the vertical array shown in Figure 9 are obtained. Subsequently, the angle in the vertical direction and the position in the vertical direction of the target detected in S130 and S140 are calculated, for example, using the DBF or monopulse method.

[0042] In S160, the processing unit 4 uses the acquisition result obtained in S130 to S150 to generate target information, which is information about the target present in the search area, outputs the target information to a downstream device which performs various processes using the target information, and terminates the present process. [1-5. Beneficial Effects]

[0043] In the present embodiment, described in detail above, the following advantageous effects are produced. (1a) In the antenna device 2, unlike the conventional device, the transmitting antennas 21 to 23 are located between the receiving antennas 24 to 27, and the plurality of receiving antennas 24, 25 are arranged at a distance d which is smaller than the reference distance D in one orientation direction when viewed from the side of the transmitting antennas 21 to 23. Consequently, the receiving antennas in the virtual array formed by the transmitting antennas 21 to 23 and the receiving antennas 24, 25 (i.e., the MRR array) and the receiving antennas in the virtual array formed by the transmitting antennas 21 to 23 and the receiving antennas 26, 27 (i.e., the LRR array) are arranged at different distances. In this way, two virtual arrays with different grid lobes can be implemented with the antenna device 2 with a configuration that is as simple as the configuration of the conventional device. (1b) The antenna device 2 is configured such that the circumscribed geometric shape of the receiving antennas 24, 25 has the same shape and size as the receiving antennas 26. Therefore, the virtual array formed from the transmitting antennas 21 to 23 and the combined antennas resulting from a combination of the receiving antennas 24, 25 (i.e., channels CH1-2, CH3-4, CH5-6) can be used as part of the virtual array formed from the transmitting antennas 21 to 23 and the receiving antenna 26 (i.e., channels CH7 to CH9). (1c) In the antenna device 2, the distance between the phase center of the receiving antenna 24 and the phase center of the receiving antenna 25 can be set to less than 0.5 λ, where λ represents the wavelength used. In this case, the use of the MRR array enables an angle measurement process that does not cause any angle ambiguity. (1d) With the antenna device 2, an angle measurement method that achieves, for example, high directional accuracy or high angular resolution can be carried out in the case where the LRR array is used. In addition, since the aperture of each channel in the LRR array is larger than in the MRR array, the antenna gain can be higher, and an object located at a greater distance can be detected. It is noted that with the LRR array, angular ambiguity due to the grating lobe occurs because of the greater distance between the receiving antennas, but this angular ambiguity can be resolved when using the MRR array in combination. (1e) In the antenna device 2, the receiving antenna 27 is provided at a position defined by moving the receiving antenna 26 in the y-axis direction. Therefore, the vertical array can be provided; the use of the vertical array allows the detection of not only an angle in the x-axis direction, but also an angle in the y-axis direction. [2. Second embodiment][2-1. Differences from the first embodiment]

[0044] The basic configuration in the second embodiment is essentially the same as that in the first embodiment; therefore, differences are described below. It should be noted that reference numerals identical to those of the first embodiment represent the same elements as those of the first embodiment; therefore, reference is made to the preceding description.

[0045] In the first embodiment described above, the aperture width of each of the receiving antennas 24, 25 in the x-axis direction and the aperture width of each of the receiving antennas 26, 27 in the x-axis direction are different. The second embodiment differs from the first embodiment in that the receiving antennas have the same aperture width and in that the receiving antennas are arranged at different distances. [2-2. Antenna device]

[0046] As in Fig. Figure 11 shows an antenna device 2a in the present embodiment comprising transmitting antennas 21a to 23a and receiving antennas 24a to 26a.

[0047] The transmitting antennas 21a to 23a have essentially the same shape as the transmitting antennas 21 to 23 in the first embodiment and are arranged in essentially the same way as the transmitting antennas 21 to 23 in the first embodiment. However, the aperture width of each of the transmitting antennas 21a to 23a in the x-axis direction is set to less than 0.5 times the reference distance D.

[0048] The receiving antennas 24a to 27a have essentially the same shape as the transmitting antennas 21a to 23a.

[0049] The receiving antennas 24a to 27a are arranged as follows, using the position of receiving antenna 24a as a reference. Receiving antenna 25a is positioned by moving receiving antenna 24a 0.5 times the reference distance D in the x-axis direction. Receiving antenna 27a is positioned by moving receiving antenna 25a 2.5 times the reference distance D in the x-axis direction. Receiving antenna 26a is positioned by moving receiving antenna 26a by the reference distance D in the x-axis direction and then by the vertical distance V in the y-axis direction.

[0050] The transmitting antennas 21a to 23a are arranged at positions defined by moving the receiving antennas 24a to 27a in the y-axis direction so that they do not overlap any of the receiving antennas 24a to 27a.

[0051] Furthermore, the transmitting antennas 21a to 23a are arranged such that the position of the phase center of each of the transmitting antennas 21a to 23a in the x-axis direction lies between the phase center of the receiving antenna 25a and the phase center of the receiving antenna 26a. [2-3. Virtual Array]

[0052] As in Fig. As shown in Figure 12, in the antenna device 2a, a virtual array with 12 virtual receiving antennas is obtained by combining the three transmitting antennas 21a to 23a and the four receiving antennas 24a to 27a. In particular, virtual receiving antennas are shown by the dashed lines in Figure 12. Fig. 12 are represented, formed at positions that are determined by moving the four receiving antennas 24a to 27a, which are defined by the solid lines in Fig. 12 are represented to define the distance D and the distance 2D in the x-axis direction.

[0053] In the following, receiving antennas 24a and 25a are referred to as channels CH1 and CH2, virtual receiving antennas located at positions defined by shifting receiving antennas 24a and 25a by a distance D are referred to as channels CH3 and CH4, and virtual receiving antennas located at positions defined by further shifting receiving antennas 24a and 25a by a distance D are referred to as channels CH5 and CH6. Furthermore, receiving antenna 26a is referred to as channel CH7, a virtual receiving antenna located at a position defined by shifting receiving antenna 26a by a distance D is referred to as channel CH8, and a virtual receiving antenna located at a position defined by further shifting receiving antenna 26a by a distance D is referred to as channel CH9.Furthermore, receiving antenna 27a is designated as channel CH10, a virtual receiving antenna located at a position defined by moving receiving antenna 27a by a distance D is designated as channel CH11, and a virtual receiving antenna located at a position defined by further moving receiving antenna 27a by a distance D is designated as channel CH12. It is noted that receiving antenna 26a corresponds to a first receiving antenna, receiving antennas 24a and 25a correspond to a second receiving antenna, and receiving antenna 27a corresponds to an additional receiving antenna.

[0054] As in Fig. As shown in Figure 13, the channels CH1 to CH7 form a uniformly spaced 7-element array (hereinafter referred to as an MRR array) in which the channels CH1 to CH7 are arranged at a distance D / 2 in the x-axis direction.

[0055] As in Fig. As shown in Figure 14, CH1, CH3, CH5, CH7, CH8 and CH9 form a uniformly spaced 6-element array (hereinafter referred to as an LRR array) in which the channels are arranged at a distance D in the x-axis direction.

[0056] As in Fig. As shown in Figure 15, the channel pair CH8 and CH10 and the channel pair CH9 and CH11 each form a 2-element array (hereinafter referred to as a vertical array) in which the channels are arranged at a distance V in the y-axis direction. [2-4. Beneficial Effects]

[0057] In the second embodiment described in detail above, the aforementioned advantageous effects (1a) and (1c) to (1e) of the first embodiment are provided, and the following additional advantageous effect is provided.

[0058] (2a) In the antenna device 2a, even with the same number of transmitting antennas 21a to 23a and receiving antennas 24a to 27a as in the antenna device 2 according to the first embodiment, the number of elements in the MRR array is 1 greater, thereby achieving an MRR array with a large aperture. [3. other embodiments]

[0059] Although the embodiments of the invention have been described above, the invention is not limited to the embodiments described above and can be implemented with various modifications.

[0060] (3a) In the foregoing embodiments, the two receiving antennas 24, 25, which are the second receiving antennas, have a circumscribed shape that corresponds to the shape of the receiving antennas 26, which are the first receiving antenna, but the invention is not limited to this example. For example, three or more second receiving antennas can have a circumscribed shape that corresponds to the shape of the first receiving antenna.

[0061] (3b) In the embodiments described above, the distance between the phase center of the receiving antenna 26 and the phase center of the combined antenna resulting from a combination of the plurality of receiving antennas 24, 25 is set to an integer multiple of the reference distance D, which need not necessarily be an integer multiple.

[0062] (3c) A plurality of functions of a structural element in the embodiments described above can be implemented by more than one structural element, and a function of a structural element in the embodiments described above can be implemented by more than one structural element. Furthermore, a plurality of functions of more than one structural element in the embodiments described above can be implemented by one structural element, and a function that is implemented by more than one structural element in the embodiments described above can be implemented by one structural element. Some of the configurations in the embodiments described above can be omitted.Furthermore, at least part of the configuration in the embodiments described above can be added to the configuration in another of the embodiments described above, or replaced by the configuration in another of the embodiments described above.

[0063] (3d) The invention can be implemented in various embodiments besides the antenna device described above, such as a system which includes the antenna device described above as a structural element, an antenna arrangement method and the like.

Claims

[1] Antenna device comprising: a plurality of transmitting antennas (21 to 23, 21a to 23a) aligned at a reference distance along an orientation direction, wherein the reference distance and the orientation direction are specified; a first receiving antenna (26, 26a) with an aperture width in the direction of orientation that is fixed to a first width that is smaller than the reference distance; and a plurality of second receiving antennas (24, 25, 24a, 25a), each having an aperture width in the direction of orientation which is fixed to a second width which is less than or equal to the first width, wherein the plurality of second receiving antennas is aligned at a distance which is less than the reference distance along the direction of orientation, wherein a distance along the direction of alignment between a phase center of the first receiving antenna and a phase center of a second receiving antenna, which is closest to the first receiving antenna among the plurality of second receiving antennas, is fixed to a length greater than or equal to a value obtained by multiplying the reference distance by a value obtained by subtracting 1 from the total number of transmitting antennas. [2] Antenna device according to claim 1, wherein the plurality of second receiving antennas are arranged such that a circumscribed geometric shape of the plurality of second receiving antennas has an area equal to an area of ​​the first receiving antenna. [3] Antenna device according to claim 1 or 2, wherein the plurality of transmitting antennas are arranged such that, when viewed in the direction of orientation, a phase center of each of the plurality of transmitting antennas is arranged between a position of a center of the first receiving antenna and a position of a center of the second receiving antenna that is closest to the first receiving antenna among the plurality of second receiving antennas. [4] Antenna device according to any one of claims 1 to 3, further comprising an additional receiving antenna (27, 27a) with the same shape as the first receiving antenna, wherein the additional receiving antenna is arranged in a position defined by moving the first receiving antenna in a direction orthogonal to the direction of orientation. [5] Antenna device according to claim 4, wherein the additional receiving antenna is arranged at a position defined by moving the first receiving antenna by a distance greater than or equal to the reference distance in the direction of alignment. [6] Antenna device according to claim 5, wherein a displacement amount for the additional receiving antenna in the direction orthogonal to the alignment direction is set to be less than an aperture width of the first receiving antenna in the direction orthogonal to the alignment direction.

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