Antenna device

Abstract

This antenna device includes: a plurality of antenna elements capable of beam scanning; and a matching layer provided between and at a gap from radiation surfaces of the plurality of antenna elements in a radiation direction of the plurality of antenna elements. The matching layer includes a substrate composed of a dielectric, and a plurality of strips provided on the substrate and composed of conductors. The plurality of strips are provided corresponding to the plurality of antenna elements, respectively, and the center of each antenna element overlaps with the corresponding strip when viewed from the radiation direction.

Description

Antenna device

[0001] The present disclosure relates to an antenna device.

[0002] Conventionally, there has been a dual-linearly polarized patch antenna including a plurality of patch antennas arranged in an array and a plurality of parasitic dipole antennas. Within each rectangular parallelepiped unit space in which each patch antenna is provided, four parasitic dipole antennas are provided at a distance from the patch antenna in the radial direction. The plurality of unit spaces are periodically arranged in an array. The four parasitic dipole antennas are located on the four sides of the unit space in plan view, are spaced apart from the patch of the patch antenna in plan view, and do not overlap with the patch (see, for example, "Measurement Results of a Prototype 26 GHz Wide-Angle Beam Scanning Dipole-Loaded Patch Array" by Tomura Takashi, Wada Takehisa, Shirane Atsushi, Okada Kenichi, Sudo Junpei, Higaki Makoto, Inoue Soichiro, and Nagashima Takashi, in "The Institute of Electronics, Information and Communication Engineers, IEICE Technical Report, A・P2022-251(2023-03)").

[0003] In a conventional linearly polarized patch antenna (antenna device), the multiple unit spaces are periodically arranged in an array, so that two parasitic dipole antennas located at the boundary between adjacent unit spaces are either integrated into one or are located very close to each other. On the other hand, at the boundary between the unit spaces located at the ends of the multiple unit spaces on the side where there is no adjacent unit space, there is no adjacent parasitic dipole antenna, so the coupling state, etc., is different from that of the parasitic dipole antenna located at the boundary between the adjacent unit spaces.

[0004] A parasitic dipole antenna located on the boundary where there are no adjacent unit spaces requires a separate design, and the structural design is likely to become complicated in order to maintain a low beam reflection coefficient even when the beam angle is changed. Also, in frequency bands above the millimeter wave band, a configuration using a patch antenna is not suitable for achieving low loss.

[0005] Therefore, an object of the present invention is to provide an antenna device that can suppress an increase in the reflection coefficient during beam scanning.

[0006] An antenna device according to an embodiment of the present disclosure includes a plurality of beam-steerable antenna elements and a matching layer spaced apart from the radiation surfaces of the plurality of antenna elements in the radiation direction of the plurality of antenna elements, the matching layer having a base made of a dielectric and a plurality of strips made of a conductor and provided on the base, the plurality of strips corresponding to the plurality of antenna elements, and the center of each antenna element overlaps with the corresponding strip when viewed from the radiation direction.

[0007] It is possible to provide an antenna device that can suppress an increase in the reflection coefficient during beam scanning.

[0008] 5 is a diagram illustrating an example of the configuration of an antenna device 300 according to an embodiment. FIG. 5 is a diagram illustrating an example of the configuration of an input section and an output section of a Butler matrix feed circuit 101. FIG. 5 is a diagram illustrating an example of the configuration of a matching layer 310. FIG. 5 is a diagram illustrating an example of the positional relationship between one output port 102B and a strip 312 corresponding to one output port 102B, as viewed in the yz plane. FIG. 5 is a diagram illustrating an example of a simulation model of a unit structure of a Butler matrix feed circuit 101 and a unit structure of a matching layer 310. FIG. 5 is a diagram illustrating an example of a simulation result of a comparative antenna device. FIG. 5 is a diagram illustrating an example of a simulation result of an antenna device 300 according to an embodiment. FIG. 5 is a perspective view illustrating an example of the configuration of a cross-crossing directional coupler 1 used in an antenna device according to a modified example of the embodiment. FIG. 5 is a cross-sectional view taken along line II-II of FIG. 5. FIG. 5 is a cross-sectional view taken along line III-III of FIG. 5. FIG. 5 is a top view illustrating the configuration of each waveguide. FIG. 5 is a diagram illustrating an example of the configuration of an antenna device 300M according to a modified example of the embodiment. FIG. 5 is a schematic view illustrating an example of a bend structure included in the antenna device 300M. 17 is a perspective view showing a configuration example of a cross-crossing directional coupler according to a second embodiment. FIG. 18 is a cross-sectional view taken along the section line XVII-XVII in FIG. 12. FIG. 19 is a cross-sectional view taken along the section line XVIII-XVIII in FIG. 12. FIG. 20 is a top view illustrating the configuration of each waveguide. FIG. 21 is a graph illustrating simulation results of the cross-crossing directional coupler according to the second embodiment. FIG. 22 is a perspective view illustrating a configuration example of a cross-crossing directional coupler according to a third embodiment. FIG. 23 is a cross-sectional view taken along the section line XXII-XXII in FIG. 17. FIG. 24 is a cross-sectional view taken along the section line XXIII-XXIII in FIG. 12. FIG. 25 is a top view illustrating the configuration of each waveguide. FIG. 26 is a graph illustrating simulation results of the cross-crossing directional coupler according to the third embodiment. FIG. 27 is a top view illustrating another configuration example of each waveguide of the cross-crossing directional coupler according to the third embodiment. FIG. 28 is a perspective view illustrating a configuration example of a cross-crossing directional coupler according to a fourth embodiment. FIG. 29 is a diagram illustrating an example of a simulation model (periodic boundary model) of the unit structure of the Butler matrix feed circuit 101 and the unit structure of the matching layer 310. FIG. 10 is a diagram showing an example of a calculation result of an admittance locus in a simulation model of the Butler matrix feed circuit 101 alone.1 is a diagram showing an example of a calculation result of an admittance locus in a simulation model of the matching layer 310 alone. FIG. 2 is a diagram showing an example of a calculation result of an admittance locus in a simulation model of the unit structure of the Butler matrix feed circuit 101 and the unit structure of the matching layer 310. FIG. 3 is a diagram showing an example of the characteristics of the S11 parameter with respect to the beam scanning angle in a simulation model of the unit structure of the Butler matrix feed circuit 101 and the unit structure of the matching layer 310. FIG. 4 is a diagram showing an example of a simulation model of a one-dimensional antenna device. FIG. 5 is a diagram showing an example of the characteristics of the S11 parameter with respect to the beam scanning angle θs in one periodic boundary model of the simulation model of a 1×8 one-dimensional antenna device. FIG. 6 is a diagram showing an example of a simulation model of a one-dimensional antenna device having a parasitic strip. FIG. 7 is a diagram showing an example of a simulation model of a one-dimensional antenna device having a parasitic strip. FIG. 8 is a diagram showing an example of the positional relationship between one output port 102B and a strip 312 and two parasitic strips 312P corresponding to one output port 102B, as viewed in the yz plane. 1 is a diagram showing an example of the positional relationship between one output port 102B and a strip 312 and two parasitic strips 312P corresponding to one output port 102B, as viewed in the yz plane. FIG. 2 is a diagram showing an example of a simulation result of the frequency characteristics of active S-parameters in an antenna device with a one-dimensional arrangement having parasitic strips. FIG. 3 is a diagram showing an example of a simulation result of the frequency characteristics of active S-parameters in an antenna device with a one-dimensional arrangement having parasitic strips. FIG. 4 is a diagram showing an example of a simulation result of the frequency characteristics of active S-parameters in an antenna device with a one-dimensional arrangement having parasitic strips. FIG. 5 is a diagram showing an example of a simulation result of the frequency characteristics of active S-parameters in an antenna device with a one-dimensional arrangement having parasitic strips.

[0009] Hereinafter, embodiments to which the antenna device of the present disclosure is applied will be described. In the following, the same elements will be given the same reference numerals, and duplicated descriptions may be omitted.

[0010] In the following description, an xyz coordinate system is defined. The direction parallel to the x-axis (x direction), the direction parallel to the y-axis (y direction), and the direction parallel to the z-axis (z direction) are perpendicular to each other. For ease of explanation, the -z direction may be referred to as the lower side or bottom, and the +z direction may be referred to as the upper side or top. Planar view refers to an xy plane view. In the following description, the length, width, thickness, etc. of each part may be exaggerated to make the configuration easier to understand. Terms such as parallel, right angle, orthogonal, horizontal, vertical, and up and down may be misaligned to the extent that they do not impair the effects of the embodiments.

[0011] In the following description, "radio waves" refers to a type of electromagnetic wave, and generally, electromagnetic waves below 3 THz are called radio waves. Hereinafter, electromagnetic waves emitted from outdoor base stations or relay stations will be referred to as "radio waves," and electromagnetic waves in general will be referred to as "electromagnetic waves." In addition, in the following, "millimeter waves" or "millimeter wave band" will include not only the frequency band of 30 GHz to 300 GHz, but also the quasi-millimeter wave band of 24 GHz to 30 GHz.

[0012] The radio waves transmitted and received by the antenna device of the embodiment are preferably in the millimeter wave band of the fifth generation mobile communication system (5G) or the like, or in the 1 GHz to 30 GHz frequency band including Sub-6. The radio waves transmitted and received by the antenna device of the embodiment may be Long Term Evolution (LTE), LTE-Advanced (LTE-A), or Ultra Mobile Broadband (UMB). The radio waves transmitted and received by the antenna device of the embodiment may be IEEE 802.11 (Wi-Fi (registered trademark)), IEEE 802.16 (WiMAX (registered trademark)), IEEE 802.20, Ultra-Wideband (UWB), Bluetooth (registered trademark), Low Power Wide Area (LPWA), or the like.

[0013] <Embodiment 1> <Antenna device 300> Fig. 1 is a diagram showing an example of the configuration of an antenna device 300 of embodiment 1. The antenna device 300 includes a Butler matrix feed circuit 101 and a matching layer 310. The Butler matrix feed circuit 101 extends in the x direction, and the matching layer 310 is arranged on the +x direction side of the Butler matrix feed circuit 101. The matching layer 310 is spaced in the +x direction from the end of the Butler matrix feed circuit 101 on the +x direction side.

[0014] <Butler matrix feed circuit 101> Figure 2 is a diagram illustrating an example of the configuration of the input section and output section of the Butler matrix feed circuit 101. The Butler matrix feed circuit 101 shown in Figure 2 has hybrid couplers, cross couplers, and phase shifters connected in multiple stages (not shown), and includes multiple input ports 102A to which input signals are input and multiple output ports 102B to which output signals are output. The multiple input ports 102A are located at the end of the Butler matrix feed circuit 101 on the -x direction side and arranged in a matrix. The multiple input ports 102A form the input section of the Butler matrix feed circuit 101. The multiple output ports 102B are located at the end of the Butler matrix feed circuit 101 on the +x direction side and arranged in a matrix. The multiple output ports 102B form the output section of the Butler matrix feed circuit 101. Note that the circle on the right side of Figure 2 shows the multiple output ports 102B as viewed from the +x direction.

[0015] 2 includes input ports 1 to 16 as input ports 102A, and output ports 17 to 32 as output ports 102B. Input ports 1 to 16 are arranged in a 4×4 matrix, and output ports 17 to 32 are arranged in a 4×4 matrix.

[0016] The Butler matrix feed circuit 101 shown in FIG. 2 is, for example, configured with waveguides, so that input ports 1 to 16 and output ports 17 to 32 are connected in space along the x direction. More specifically, input port 1 is connected in space along the x direction with output port 17, and input port 1 and output port 17 are positioned at the same location when viewed in the yz plane. Input port 2 is connected in space along the x direction with output port 18, and input port 2 and output port 18 are positioned at the same location when viewed in the yz plane. This also applies to input ports 3 to 15 and output ports 19 to 31. Furthermore, input port 16 is connected in space along the x direction with output port 32, and input port 16 and output port 62 are positioned at the same location when viewed in the yz plane.

[0017] In this way, the Butler matrix feed circuit 101 has a configuration in which unit structures each including one input port 102A and one output port 102B are periodically arranged in the y direction and the z direction.

[0018] When input signals are input to the multiple input ports 102A of the Butler matrix feed circuit 101 and output signals are output from the multiple output ports 102B, the multiple output ports 102B function as multiple antenna elements that radiate radio waves based on the output signals. As an example, the polarization direction of the radio waves radiated from each output port 102B is assumed to be parallel to the z direction. That is, as an example, the radio waves radiated from each output port 102B are vertically polarized radio waves.

[0019] Here, a configuration will be described in which the port on the −x side of the Butler matrix feed circuit 101 is the input port 102A, and the port on the +x side of the Butler matrix feed circuit 101 is the output port 102B, but the reverse is also possible.

[0020] Furthermore, the Butler matrix feed circuit 101 is not limited to being configured with a waveguide, but may be configured with a transmission line such as a microstrip line, or a high-frequency circuit, for example.

[0021] In Butler matrix feeder 101, the direction of the beam output from output port 102B changes depending on the position of input signals input to input ports 1 to 16. For example, Butler matrix feeder 101 is used in a phased array antenna that changes the beam direction two-dimensionally.

[0022] In the Butler matrix feed circuit 101, the direction in which an input signal is input and the direction in which an output signal is output are the same (x direction).

[0023] 3A is a diagram showing an example of the configuration of the matching layer 310. The matching layer 310 has a substrate 311 and a plurality of strips 312. The substrate 311 is an example of a base.

[0024] <Substrate 311> The substrate 311 may be any substrate made of a dielectric material, and may be, for example, a resin substrate, a rigid substrate, or a flexible substrate. The substrate 311 may be a wiring substrate conforming to the FR4 (Flame Retardant type 4) standard or the like. For example, the flexible substrate may be made of resin such as polyimide, fluororesin, maleimide resin, or cycloolefin polymer, or liquid crystal polymer. For example, the rigid substrate may be made of PPE (polyphenylene ether). The substrate 311 may also be made of glass such as soda glass, alkali-free glass, or quartz glass.

[0025] <Strips 312> As an example, the multiple strips 312 are provided on the surface on the −x direction side of the substrate 311. The surface on the −x direction side faces the multiple output ports 102B of the Butler matrix feed circuit 101. The multiple strips 312 may also be provided on the surface on the +x direction side of the substrate 311. Furthermore, if the substrate 311 is a multilayer substrate, the multiple strips 312 may be provided on an inner layer.

[0026] The plurality of strips 312 can be made of copper or aluminum, for example. The plurality of strips 312 extend parallel to the z direction, for example. The plurality of strips 312 are all parallel to one another. Each strip 312 has a longitudinal direction extending in the z direction and is a linear conductor layer in plan view. The plurality of strips 312 extend parallel to the polarization direction of the radio waves emitted from the plurality of strips 312.

[0027] Here, as an example, the case where the radio waves are vertically polarized will be described, and therefore the strips 312 extend in the z direction, but if the radio waves are horizontally polarized, the strips 312 may extend in the y direction. Also, if there are both vertically polarized and horizontally polarized radio waves, a cross-shaped strip may be used that combines the strips 312 extending in the z direction with the strips 312 extending in the y direction.

[0028] The number of the plurality of strips 312 is equal to the number of output ports 102B of the Butler matrix feeding circuit 101. As the Butler matrix feeding circuit 101 shown in Figures 1 and 2 has, as an example, 16 output ports 102B, the number of the plurality of strips 312 is, as an example, 16.

[0029] The 16 strips 312 are provided at positions corresponding to the 16 output ports 102B when viewed in the yz plane. In other words, when viewed in the yz plane, one strip 312 is provided corresponding to each output port 102B. Viewing the output ports 102B and the strips 312 in the yz plane means viewing the output ports 102B and the strips 312 from the radial direction of the output ports 102B.

[0030] The matching layer 310 has a configuration in which unit structures, each including one strip 312, are periodically arranged in the y and z directions. The unit structures of the matching layer 310 are arranged to correspond to the unit structures of the Butler matrix feed circuit 101, respectively, when viewed in the yz plane.

[0031] 3B is a diagram showing an example of the positional relationship between one output port 102B and the strip 312 corresponding to that output port 102B in the yz plane. In FIG. 3B, the outline of one of the 16 output ports 102B is shown by a dashed line as an example. The center 102B1 of the output port 102B in the yz plane is also shown. Note that, as an example, the polarization direction of the radio wave at the output port 102B is the z direction, i.e., vertical polarization.

[0032] The strip 312 extends in the z direction through the center of the corresponding output port 102B in the yz plane. The strip 312 is disposed so as to overlap the center 102B1 of the output port 102B in the yz plane.

[0033] In FIG. 3B , as an example, both ends of strip 312 in the z direction are located outside both ends of output port 102B in the z direction, but both ends of strip 312 in the z direction may coincide with the positions of both ends of output port 102B in the z direction, or may be located inside both ends of output port 102B in the z direction.

[0034] The strip 312 is arranged symmetrically in the z direction with respect to the output port 102B. More specifically, in the z direction, the center 102B1 of the output port 102B is located at the center of both ends of the strip 312 in the z direction. Because the z direction is the polarization direction of the radio waves at the output port 102B, it is preferable that the strip 312 be symmetrical in the z direction with respect to the output port 102B.

[0035] Moreover, the strip 312 is arranged symmetrically in the y direction with respect to the output port 102B. More specifically, in the y direction, the center 102B1 of the output port 102B is located at the center of both ends of the strip 312 in the y direction. Note that, because the y direction is 90 degrees different from the polarization direction of the radio waves at the output port 102B, the centers of both ends of the strip 312 in the y direction and the center 102B1 of the output port 102B may be slightly misaligned.

[0036] The centers of both ends of each strip 312 in the y direction may be offset from the center 102B1 of the corresponding output port 102B, but the center 102B1 of each output port 102B only needs to overlap with the corresponding strip 312 when viewed from the radial direction (+x direction).

[0037] The strip 312 is arranged symmetrically in the z direction with respect to the output port 102B, so that the strip 312 overlaps with the center of the output port 102B in the z direction.

[0038] Therefore, when viewed from the radial direction (+x direction), overlapping of the center 102B1 of the output port 102B with the corresponding strip 312 means that there is little misalignment in the y direction between the center 102B1 and the strip 312, and that there is an overlapping portion in the y direction.

[0039] Furthermore, in the yz plane view, the distance in the direction (y direction) perpendicular to the polarization direction (z direction) of the radio waves between the center 102B1 of the output port 102B and the center of the width Sy (see FIG. 3B ) of the corresponding strip 312 in the direction (y direction) perpendicular to the polarization direction (z direction) of the radio waves may be λe / 4 or less, where λe is the electrical length of the wavelength taking into account the dielectric constant between the output port 102B and the strip 312 at the operating frequency at which the multiple output ports 102B operate as antenna elements. The electrical length of the wavelength taking into account the dielectric constant between the output port 102B and the strip 312 is the electrical length of the wavelength at the operating frequency of the output port 102B.

[0040] This is because, if the distance in the y direction between the center 102B1 of the output port 102B and the center of the width Sy of the corresponding strip 312 is λe / 4 or less, the electromagnetic field coupling between the strip 312 and the output port 102B allows the reflection coefficient of the beam to remain low even if the antenna device 300 changes the beam angle.

[0041] <Simulation model of unit structure of Butler matrix feed circuit 101 and unit structure of matching layer 310> Figure 3C is a diagram illustrating an example of a simulation model of the unit structure of the Butler matrix feed circuit 101 and the unit structure of the matching layer 310. Although Figure 3C shows the configuration as a simulation model, the actual unit structure of the Butler matrix feed circuit 101 and the actual unit structure of the matching layer 310 have the same configuration as the simulation model.

[0042] <Unit structure of Butler matrix feed circuit 101> In Figure 3C, the unit structure of the Butler matrix feed circuit 101 shows a portion of the end of the waveguide inside the waveguide on the +x direction side, with the metal parts of the waveguide, SIW (Substrate Integrated waveguide), or post-wall waveguide omitted. Hereinafter, the waveguide refers to the waveguide, SIW, or post-wall waveguide. The unit structure of the Butler matrix feed circuit 101 has lengths Py101 and Pz101 in the y and z directions. Figure 3C also shows the portion of the unit structure of the Butler matrix feed circuit 101 on the +x direction side with length Px101.

[0043] The waveguide included in the unit structure of the Butler matrix feed circuit 101 has lengths a and b in the y and z directions. The rectangular opening at the end of the waveguide in the positive x direction is the output port 102B.

[0044] 3C shows two posts 102B2 inside the waveguide, slightly to the −x direction side of output port 102B. The distance between the two posts 102B2 and output port 102B is Cx.

[0045] For example, the two posts 102B2 are arranged at the ±y-direction ends of the waveguide so as to extend in the z-direction. The two posts 102B2 connect the ±z-direction walls of the waveguide (waveguide walls). These two posts 102B2 are provided to improve the radiation of radio waves from the output port 102B. The two posts 102B2 may also be provided in the waveguide of the actual Butler matrix feed circuit 101.

[0046] <Unit Structure of Matching Layer 310> The unit structure of the matching layer 310 is disposed at a position spaced a distance Px from the output port 102B in the +x direction. The unit structure of the matching layer 310 is composed of one strip 312 and a portion of the substrate 311 that corresponds to the one strip 312.

[0047] The thickness of the substrate 311 in the x direction is dx, and the lengths in the y direction and z direction of a portion of the substrate 311 corresponding to one strip 312 are Py and Pz, respectively. The length Py is equal to the length Py101 in the y direction of the unit structure of the Butler matrix feed circuit 101. The length Pz is equal to the length Pz101 in the z direction of the unit structure of the Butler matrix feed circuit 101. The length Sz in the z direction of the strip 312. The width Sy in the y direction of the strip 312 is as shown in FIG. 3B .

[0048] <Simulation Results> A simulation was performed on the antenna device 300 with the lengths of each component set to the following values. The y-direction length a of the waveguide of the Butler matrix feed circuit 101 was set to 1.000 mm, and the z-direction length b of the waveguide was set to 0.370 mm. The y-direction length Py of one unit structure of the substrate 311 was set to 1.200 mm, and the z-direction length Pz was set to 0.624 mm. The distance Cx of the two posts 102B2 from the output port 102B was set to 0.850 mm, and the distance Px of the matching layer 310 from the output port 102B in the +x direction was set to 0.490 mm. The length Sz of the strip 312 was set to 0.400 mm, and the width Sy of the strip 312 was set to 0.127 mm. Note that, when viewed in the yz plane, the center of the strip 312 was aligned with the center 102B1 of the output port 102B.

[0049] Simulations were also performed on a comparative antenna device. The comparative antenna device has a configuration in which the matching layer 310 is omitted from the antenna device 300 of the first embodiment. The lengths a and b, the length Py, and the length Pz of the comparative antenna device are the same as those of the antenna device 300 described above. In addition, for the comparative antenna device, the distance Cx was set to 0.770 mm.

[0050] 4A is a diagram showing an example of simulation results for a comparative antenna device, in which the horizontal axis represents the frequency of the radio wave radiated from output port 102B of Butler matrix feed circuit 101, and the vertical axis represents the value of the S11 parameter, which is a parameter that represents the portion of the power input from input port 102A that is not radiated from output port 102B but returns to input port 102A.

[0051] In the simulation, a phase difference was provided between radio waves input from the input port 102A and emitted from the output port 102B adjacent in the y direction, thereby performing beam scanning so as to form an angle with respect to the +x direction within the xy plane.

[0052] 4A shows the characteristics when the direction of the beams radiated from adjacent output ports 102B in the y direction of the Butler matrix feed circuit 101 (the downward angle from the x-axis in the xy plane in FIG. 3C) is 0 degrees, 20 degrees, 40 degrees, 60 degrees, and 70 degrees. The Butler matrix feed circuit 101 is configured so that the reflection coefficient is minimized in the 120 GHz band when the phase difference between the radio waves radiated from adjacent output ports 102B in the y direction is 0 degree.

[0053] As shown in Figure 4A, when the phase difference between the radio waves emitted from adjacent output ports 102B in the y direction is 0 degrees, as the phase difference between the radio waves increases to 20 degrees, 40 degrees, 60 degrees, and 70 degrees, the reflection coefficient increases and the frequency band at which the reflection coefficient is minimum tends to decrease.

[0054] Fig. 4B is a diagram showing an example of a simulation result for the antenna device 300 of embodiment 1. The horizontal and vertical axes in Fig. 4B are the same as those in Fig. 4A. As in the comparative antenna device, the Butler matrix feed circuit 101 in the antenna device 300 of embodiment 1 is also configured so that the reflection coefficient is minimized in the 120 GHz band when the phase difference between radio waves radiated from adjacent output ports 102B in the y direction is 0 degree.

[0055] As shown in Figure 4B, when the phase difference between the radio waves radiated from adjacent output ports 102B in the y direction is 0 degree, the increase in the reflection coefficient is suppressed even when the beam direction (the downward angle from the x-axis in the xy plane in Figure 3C) is increased to 20 degrees, 40 degrees, 60 degrees, and 70 degrees. The frequency band at which the reflection coefficient is minimum tends to decrease as the phase difference between the radio waves increases, similar to the comparative antenna device, but it was confirmed that the increase in the reflection coefficient can be significantly suppressed.

[0056] Through the simulation, the following was found:

[0057] It has been found that the ratio Sz / Pz of the length Sz to the length Pz is preferably 0.3 or more and 1 or less.

[0058] Furthermore, it was found that, when the electrical length of the wavelength taking into account the dielectric constant between the output port 102B and the strip 312 is λe, it is preferable that the distance Px be 0.1 λe or more and 0.5 λe or less, and that the thickness dx be 10 μm or more and 10 mm or less.

[0059] It was also found that it is preferable that the beams emitted from the multiple output ports 102B have a reflection coefficient of -15 dB or less when the absolute value of the beam scanning angle is 60 degrees. In the case of vertically polarized radio waves, the beam scanning angle is the angle of the arc drawn from the +x direction toward the y axis in the xy plane.

[0060] <Modification of First Embodiment> Depending on the application of the antenna device 300, it may be desirable to bend the propagation direction of the output signal output from the Butler matrix feed circuit 101. For example, when the Butler matrix feed circuit 101 is mounted on a window glass or a wall surface, it may be desirable to output the output signal in a direction perpendicular to the propagation direction of the signal in the Butler matrix feed circuit 101.

[0061] In the modified example, an antenna device including a bent structure using a cross-shaped directional coupler will be described. First, the cross-shaped directional coupler will be described with reference to FIGS.

[0062] Fig. 5 is a perspective view showing a configuration example of a cruciform directional coupler 1 used in an antenna device according to a modified example of the first embodiment. Fig. 6 is a cross-sectional view taken along line II-II in Fig. 5. Fig. 7 is a cross-sectional view taken along line III-III in Fig. 5. Fig. 8 is a top view illustrating the configuration of each waveguide.

[0063] 5 to 7, the cross-shaped directional coupler 1 includes a first waveguide 111, a second waveguide 112, and a third waveguide 113. The first to third waveguides 111 to 113 are stacked in the z-axis direction in the order of the second waveguide 112, the first waveguide 111, and the third waveguide 113.

[0064] As shown in FIG. 6 , the first waveguide 111 has a first port P1 at one end in the waveguiding direction (the negative side in the x-axis direction) and a third port P3 at the other end in the waveguiding direction (the positive side in the x-axis direction). The second waveguide 112 has a second port P2 at one end in the waveguiding direction (the negative side in the x-axis direction), and the output port 17 opposite the second port P2 is short-circuited. The second waveguide 112 is disposed below the first waveguide 111. The third waveguide 113 has a fourth port P4 at one end in the waveguiding direction (the positive side in the x-axis direction), and the output port 18 opposite the fourth port P4 is short-circuited. The third waveguide 113 is disposed above the first waveguide 111.

[0065] As shown in Figures 6 and 7, the first waveguide 111 and the second waveguide 112 each have one first slot SL1. The two first slots SL1 are aligned and communicate with each other when viewed in the xy plane. In the following, the two first slots SL1 are described as being integrated. Furthermore, the first waveguide 111 and the third waveguide 113 each have one second slot SL2. The two second slots SL2 are aligned and communicate with each other when viewed in the xy plane. In the following, the two second slots SL2 are described as being integrated with each other.

[0066] 7 and 8, the first slot SL1 and the second slot SL2 are disposed on the lower and upper surfaces of the first waveguide 111 at the center in the width direction (y-axis direction) of the first waveguide 111. That is, as shown in Fig. 8, the first slot SL1 and the second slot SL2 are provided symmetrically along the central axis C1 of the first waveguide 111.

[0067] As shown in Figures 7 and 8, the first slot SL1 and the second slot SL2 are disposed on the upper surface of the second waveguide 112 and the lower surface of the third waveguide 113, offset by a predetermined distance D1 from the center of the second waveguide 112 and the third waveguide 113 in the width direction (y-axis direction). That is, as shown in Figure 8, the first slot SL1 is disposed offset by the distance D1 from the center axis C2 of the second waveguide 112. Furthermore, the second slot SL2 is disposed offset by the distance D1 from the center axis C2 of the third waveguide 113. Note that the center axis C2 of the second waveguide 112 and the center axis C2 of the third waveguide 113 overlap when viewed from the z-axis direction. Furthermore, the first slot SL1 and the second slot SL2 overlap when viewed from the z-axis direction.

[0068] 7 , for example, the positions of the second waveguide 112 and the third waveguide 113 in the y-axis direction are aligned, and the position of the first waveguide 111 in the y-axis direction is shifted toward the positive side of the y-axis direction relative to the second waveguide 112 and the third waveguide 113. With this configuration, the positions of the first slot SL1 and the second slot SL2 can be offset by a predetermined distance D1 from the center of the second waveguide 112 and the third waveguide 113 in the width direction (y-axis direction).

[0069] The first to third waveguides 111 to 113 can be configured using rectangular parallelepiped waveguides. For example, the first to third waveguides 111 to 113 are hollow waveguides through which electromagnetic waves propagate. Furthermore, a dielectric material may be disposed inside the first to third waveguides 111 to 113. For example, the first to third waveguides 111 to 113 may be configured using a hollow metal material, or may be configured by forming a metal film on the inner wall of a hollow resin material.

[0070] For example, in the case of the TE10 mode in a rectangular waveguide, the length in the y-axis direction (long side a) and the length in the z-axis direction (short side b) of the first to third waveguides 111 to 113 can be determined as follows.

[0071] First, the cutoff frequency f of the first to third waveguides 111 to 113 (hereinafter collectively referred to as "waveguides") ｃ is determined by the following formula:

[0072] Here, c p is the velocity of the electromagnetic wave in the dielectric, a is the length of the long side of the waveguide, b is the length of the short side of the waveguide, and m and n are mode numbers. p can be expressed by the following formula:

[0073] where ε ０ is the dielectric constant of a vacuum, ε ｒ is the relative permittivity of the dielectric, μ ０ is the permeability of a vacuum, μ ｒ is the relative permeability of the dielectric.

[0074] In the TE10 mode, which is the fundamental propagation mode, f ｃ is expressed as follows:

[0075]

[0076] Furthermore, when a substrate integrated waveguide (SIW) is used, the above a can be expressed as the following a ｓ It will look like this.

[0077] Here, a ｄ is the length of the substrate integrated waveguide in the y-axis direction (length of the long side), d is the diameter of the via, and p is the pitch. Also, A is 0.5≦A<1.5.

[0078] For example, the relative dielectric constant of the dielectric is 3.6, and a ｄ When the cutoff frequency is set to f = 0.924 mm, ｃ = 83 GHz. Generally, b≦a / 2 is set to avoid the occurrence of unwanted propagation modes other than the desired mode.

[0079] f obtained from the above formula ｃ ga f ｃ <<The dimensions a and b of the waveguide are determined so as to achieve the design frequency. As an example, the length in the y-axis direction (long side a) of the first to third waveguides 111 to 113 can be a = 0.924 mm, and the length in the z-axis direction (short side b) can be b = 0.35.

[0080] The first slot SL1 and the second slot SL2 can be configured by forming holes in the first to third waveguides 111 to 113. Specifically, the first slot SL1 can be configured by partially cutting out the bottom surface of the first waveguide 111 and the top surface of the second waveguide 112 to form holes. The second slot SL2 can be configured by partially cutting out the top surface of the first waveguide 111 and the bottom surface of the third waveguide 113 to form holes.

[0081] For example, the dimensions of the first slot SL1 and the second slot SL2 can be determined as follows: If the design frequency is 120 GHz, the wavelength λ of 120 GHz is approximately 2.5 mm. ｇ is about 1.28 mm, and λ ｇ / 2 = 0.64 mm.

[0082] The short sides of the slots SL1 and SL2 are determined by adjusting the electromagnetic coupling. ＳＬ１ can be determined to be in the following range:

[0083] λ ｇ / 8≦L ＳＬ１ ≦2λ ｇ

[0084] In addition, the long side L of the slot SL1 ＳＬ１ and the long side L of slot SL2 ＳＬ２ can be made to be of the same size, so the long side L of slot SL2 ＳＬ２ can be determined to be in the following range:

[0085] 0.5L ＳＬ１ ≦L ＳＬ２ ≦1.5L ＳＬ１

[0086] As an example, if the dimensions of the long side a and short side b of the first to third waveguides 111 to 113 are the above dimensions (a = 0.924 mm, b = 0.35), the dimensions of the first slot SL1 and the second slot SL2 can be 0.132 mm x 0.660 mm.

[0087] In the cross-shaped directional coupler 1, the second waveguide 112 and the third waveguide 113 are coupled to each other via the first slot SL1, the first waveguide 111, and the second slot SL2. In other words, the second waveguide 112 and the third waveguide 113 are coupled to the first slot SL1 and the second slot SL2, and are also coupled to each other via the first waveguide 111.

[0088] Therefore, the electromagnetic wave supplied to the second port P2 of the second waveguide 112 propagates through the first slot SL1, the first waveguide 111, and the second slot SL2 to the third waveguide 113 and is output from the fourth port P4 of the third waveguide 113. In addition, the electromagnetic wave supplied to the first port P1 of the first waveguide 111 is output from the third port P3 of the first waveguide 111.

[0089] That is, in the first waveguide 111, the first slot SL1 and the second slot SL2 are provided symmetrically along the central axis C1 of the first waveguide 111. Therefore, no potential difference is generated in the TE10 mode of the first waveguide 111, and therefore the first waveguide 111 is not coupled to the first slot SL1 or the second slot SL2. Therefore, an electromagnetic wave supplied to the first port P1 of the first waveguide 111 is output from the third port P3 of the first waveguide 111.

[0090] On the other hand, the first slot SL1 and the second slot SL2 in the second waveguide 112 and the third waveguide 113 are offset by a distance D1 from the central axis C2 of the second waveguide 112 and the third waveguide 113. In other words, the first slot SL1 and the second slot SL2 in the second waveguide 112 and the third waveguide 113 are arranged asymmetrically with respect to the central axis C2. Therefore, the second waveguide 112 and the third waveguide 113 are coupled to the first slot SL1 and the second slot SL2, and are also coupled to each other via the first waveguide 111. At this time, because the first slot SL1 and the second slot SL2 are arranged centrally with respect to the first waveguide 111, the second waveguide 112 and the third waveguide 113 are not coupled to the first waveguide 111. Therefore, the electromagnetic wave supplied to the second port P2 of the second waveguide 112 propagates through the first slot SL1, the first waveguide 111, and the second slot SL2 to the third waveguide 113 and is output from the fourth port P4 of the third waveguide 113. Here, the path between the second port P2 and the fourth port P4 is a path that passes vertically through the first waveguide 111.

[0091] The above-mentioned predetermined distance (offset distance) D1 can be determined arbitrarily depending on the design of the cross-cross directional coupler 1. That is, the offset distance D1 can be any distance so long as the second waveguide 112 and the third waveguide 113 are coupled to the first slot SL1 and the second slot SL2, and the first waveguide 111 is not coupled to the first slot SL1 and the second slot SL2. Here, "the first waveguide 111 is not coupled to the first slot SL1 and the second slot SL2" also includes the case where the first waveguide 111 is weakly coupled to the first slot SL1 and the second slot SL2. That is, as long as it does not significantly affect the design of the cross-cross directional coupler 1, the case where the first waveguide 111 is weakly coupled to the first slot SL1 and the second slot SL2 may also be included.

[0092] As an example, the predetermined distance (offset distance) D1 is preferably in the range of 1% to 50% of the width (distance in the y-axis direction) of the second waveguide 112 and the third waveguide 113, more preferably in the range of 1% to 35%, and even more preferably in the range of 5% to 25%.

[0093] 8 shows an example in which the first slot SL1 and the second slot SL2 are rectangular in shape extending in the waveguide direction (x-axis direction). However, the first slot SL1 and the second slot SL2 may be rectangular in shape extending in the width direction of the waveguide (y-axis direction), or may be cross-shaped. In other words, the first slot SL1 and the second slot SL2 may be any shape as long as the second waveguide 112 and the third waveguide 113 are coupled to the first slot SL1 and the second slot SL2.

[0094] The cross-cross directional coupler 1 is also capable of propagating electromagnetic waves in opposite directions from each port. That is, when an electromagnetic wave is supplied to the third port P3 of the first waveguide 111, the electromagnetic wave is output from the first port P1 of the first waveguide 111. When an electromagnetic wave is supplied to the fourth port P4 of the third waveguide 113, the electromagnetic wave propagates through the second slot SL2, the first waveguide 111, and the first slot SL1 to the second waveguide 112 and is output from the second port P2 of the second waveguide 112.

[0095] In a modification of the first embodiment, as shown in FIG. 9 , an antenna device 300M is provided with a bend structure 130 on the output port 102B side of the Butler matrix feed circuit 101, so that the direction of the output signal output from the Butler matrix feed circuit 101 is bent 90 degrees relative to the direction of the input signal. The antenna device 300M further includes a matching layer 310 on the bend structure 130. In FIG. 9 , the matching layer 310 is shown transparently with dashed lines to make the output ports 141 and other components more easily visible. In the antenna device 300M shown in FIG. 9 , an output section 140 is provided on the surface of the bend structure 130 on the positive side in the z-axis direction. The output section 140 is provided with output ports 141 corresponding to the output ports 102B (see FIG. 2 ) of the Butler matrix feed circuit 101, respectively. In other words, a plurality of output ports 141 are arranged in a matrix on the surface of the bend structure 130 on the positive side in the z-axis direction. 9 , the direction (x-axis direction) of the output signal output from output port 102B of Butler matrix feed circuit 101 can be bent to the z-axis direction using bend structure 130. As a result, beam 150 is radiated in the z-axis direction from output section 140 of bend structure 130.

[0096] Next, the bend structure 130 will be described in detail. FIG. 10 is a schematic diagram illustrating an example of a bend structure included in the antenna device 300M. The bend structure 130 has a function of bending the output direction of an output signal output from the output port 102B of the Butler matrix feed circuit 101 by 90 degrees. In other words, the bend structure 130 has a function of bending the direction of the output signal of the Butler matrix feed circuit 101 from the x-axis direction to the z-axis direction. Note that FIG. 10 illustrates, as an example, a configuration in which the directions of the output signals from ports 20, 24, 28, and 32 of the output port 102B of the Butler matrix feed circuit 101 shown in FIG. 2 are bent from the x-axis direction to the z-axis direction. Note that the bend structures of the other ports of the output port 102B can be configured in a similar manner.

[0097] 10 , the output signal output from port 20 propagates through waveguide 201, is bent vertically at a predetermined position within waveguide 201, and is radiated from port V20 in the positive direction in the z-axis direction. The output signal output from port 24 propagates through waveguide 202, is bent vertically at a predetermined position within waveguide 202, and is radiated from port V24 in the positive direction in the z-axis direction. The output signal output from port 28 propagates through waveguide 203, is bent vertically at a predetermined position within waveguide 203, and is radiated from port V28 in the positive direction in the z-axis direction. The output signal output from port 32 propagates through waveguide 204, is bent vertically at a predetermined position within waveguide 204, and is radiated from port V32 in the positive direction in the z-axis direction.

[0098] 10 , there is a location where a signal propagating in the x-axis direction and a signal propagating in the z-axis direction intersect. For example, at the location indicated by the reference numeral 210, a signal propagating in the x-axis direction output from port 24 intersects with a signal bent in the z-axis direction after being output from port 28. Here, a cross-shaped directional coupler 1 is used at the location where the signals intersect.

[0099] The antenna device 300M also includes a matching layer 310 provided on the +Z direction side of the bend structure 130. The matching layer 310 is the same as the matching layer 310 shown in Figures 3A to 3C, and has a plurality of strips 312 (see Figure 3A) corresponding to the plurality of output ports 141 arranged on the surface on the +Z direction side of the bend structure 130. The matching layer 310 of the antenna device 300M is provided parallel to the xy plane as shown in Figures 9 and 10, and the plurality of strips 312 are provided on the surface on the -Z direction side of the substrate 311 as shown in Figure 10, for example. Each strip 312 extends in the x direction as shown in Figure 10. That is, the longitudinal direction of each strip 312 is the x direction.

[0100] The strips 312 are provided corresponding to the output ports 141, respectively. When viewed from the radiation direction (+z direction), the center of each output port 141 overlaps with the corresponding strip 312. This is as described for the antenna device 300 using FIG. 3B .

[0101] FIG. 11 is a schematic diagram illustrating an example of a bend structure, illustrating a configuration example in which the bend structure 130 shown in FIG. 10 is configured using the cross-cross directional coupler 1 described in embodiment 1. The bend structure 130 shown in FIG. 11 is configured using cross-cross directional couplers 1a to 1f and phase shifters 5a to 5f. The phase shifters 5a to 5f have the function of adjusting the phase of signals passing through them. Each of the cross-cross directional couplers 1a to 1f is labeled with a port number P1 to P4 corresponding to the cross-cross directional coupler 1 described in embodiment 1. In addition, in FIG. 11, the ports for signals introduced into the bend structure 130 are labeled H1 to H4, and the ports for signals output from the bend structure 130 are labeled V1 to V4.

[0102] 11, a signal introduced from port H1 is supplied to port P2 of the cross-cross directional coupler 1a, and then output from port P4 of the cross-cross directional coupler 1a, passes through ports P2 and P4 of the cross-cross directional coupler 1b, and ports P2 and P4 of the cross-cross directional coupler 1c, and is output from output port V4 of the bend structure 130.

[0103] The signal introduced from port H2 is supplied to port P1 of the cross-cross directional coupler 1a, and then output from port P3 of the cross-cross directional coupler 1a, passes through phase shifter 5a, passes through ports P2 and P4 of the cross-cross directional coupler 1d, and ports P2 and P4 of the cross-cross directional coupler 1e, and is output from output port V3 of the bend structure 130.

[0104] The signal introduced from port H3 is supplied to port P1 of the cross-cross directional coupler 1b, and then output from port P3 of the cross-cross directional coupler 1b, passes through phase shifter 5b, then passes through ports P1 and P3 of the cross-cross directional coupler 1d, phase shifter 5d, and ports P2 and P4 of the cross-cross directional coupler 1f, and is output from output port V2 of the bend structure 130.

[0105] The signal introduced from port H4 is supplied to port P1 of the cross-cross directional coupler 1c, and then output from port P3 of the cross-cross directional coupler 1c, passes through phase shifter 5c, then passes through ports P1 and P3 of the cross-cross directional coupler 1e, phase shifter 5e, ports P1 and P3 of the cross-cross directional coupler 1f, and phase shifter 5f, and is output from output port V1 of the bend structure 130.

[0106] In this way, the bend structure 130 is configured using the cross-shaped directional couplers 1a to 1f, so the configuration of the bend structure 130 can be simplified. Furthermore, when the cross-shaped directional couplers 1a to 1f are used, it is possible to allow the signals to cross each other. Therefore, the differences in the path lengths of the paths, i.e., the path length from port H1 to port V4, the path length from port H2 to port V3, the path length from port H3 to port V2, and the path length from port H4 to port V1, can be reduced. Furthermore, since there is no need to connect the beam switching circuit and the bending circuit with a connector, the bend structure can be formed as an integrated unit.

[0107] The antenna device 300M according to the modification of the first embodiment includes a Butler matrix feed circuit 101 implemented using a waveguide and having a plurality of output ports, a bend structure 130 that bends the propagation direction of electromagnetic waves output from the plurality of output ports by 90 degrees and has a plurality of output ports that radiate the electromagnetic waves in a radiation direction bent by 90 degrees from the propagation direction, and a matching layer 310 provided at intervals between the plurality of output ports 141 of the bend structure 130. The matching layer 310 includes a substrate 311 made of a dielectric material and a plurality of strips 312 made of a conductor and provided on the substrate 311, the plurality of strips 312 corresponding to the plurality of output ports 141, respectively, and the center of each output port 141 overlaps with the corresponding strip 312 when viewed from the radiation direction.

[0108] <Effects> The antenna device 300 includes a plurality of antenna elements (output port 102B) capable of beam scanning, and a matching layer 310 provided at a distance from the radiation surface of the plurality of antenna elements (output port 102B) in the radiation direction (x direction) of the plurality of antenna elements (output port 102B), and the matching layer 310 has a substrate 311 made of a dielectric, and a plurality of strips 312 made of a conductor and provided on the substrate 311, and the plurality of strips 312 are provided corresponding to the plurality of antenna elements (output port 102B), respectively, and the center of each antenna element (output port 102B) overlaps with the corresponding strip 312 when viewed from the radiation direction (x direction). Therefore, when viewed from the radiation direction, each strip 312 is located at the center of the antenna element (output port 102B), and even if multiple strips 312 are arranged corresponding to multiple antenna elements (output ports 102B), the coupling state between the strips 312 and the antenna element (output port 102B) can be made equal at the center and end parts of the antenna device 300 when viewed from the radiation direction (x direction).

[0109] Therefore, it is possible to provide the antenna device 300 that can suppress an increase in the reflection coefficient during beam scanning.

[0110] Furthermore, the strips 312 may extend along the polarization direction of the radio waves emitted from the antenna elements (output port 102B). By extending the strips 312 along the polarization direction of the radio waves, the scanning angle characteristics of the reflection coefficient can be matched according to the scanning angle, and the reflection coefficient can be kept low when the beam is scanned, while suppressing fluctuations in the reflection coefficient due to the scanning angle.

[0111] Furthermore, when viewed from the radiation direction, the substrate 311 has a plurality of periodic regions respectively corresponding to the plurality of antenna elements (output ports 102B), and where Pz represents the length of the plurality of periodic regions in the polarization direction of the radio waves, and Sz represents the length of the strip 312 in the polarization direction of the radio waves, the ratio Sz / Pz of the length Sz to the length Pz may be 0.3 or more and 1 or less. By setting the ratio Sz / Pz to 0.3 or more and 1 or less, the directivity of the radio waves can be further improved, and the reflection coefficient can be kept low when the beam is scanned, while further suppressing fluctuations in the reflection coefficient due to the scanning angle.

[0112] Furthermore, the distance in the direction perpendicular to the polarization direction of the radio waves between the center of each antenna element (output port 102B) and the center of the width of the corresponding strip 312 in the direction perpendicular to the polarization direction of the radio waves may be λe / 4 or less, where λe is the electrical length of the wavelength at the operating frequency of the multiple antenna elements (output port 102B). Even if the antenna device 300 changes the angle of the beam, the reflection coefficient of the beam can be kept low.

[0113] Furthermore, if the distance in the radiation direction between the radiation surfaces of the plurality of antenna elements (output port 102B) and the plurality of strips 312 is Px, the thickness in the radiation direction of the substrate 311 is dx, and the wavelength at the operating frequency of the plurality of antenna elements (output port 102B) is λ, the distance Px may be 0.1 λe or more and 0.5 λe or less, and the thickness dx may be 10 μm or more and 10 mm or less. By setting the distance Px and the thickness dx to such values, the directivity of the radio wave can be further improved, and the reflection coefficient can be kept low when the beam is scanned, while further suppressing fluctuations in the reflection coefficient due to the scanning angle.

[0114] Furthermore, the multiple antenna elements (output port 102B) may be configured as input / output units of Butler matrix feed circuit 101. By using the input / output units of Butler matrix feed circuit 101 as multiple antenna elements, it is possible to provide antenna device 300 with a simple configuration that can suppress an increase in the reflection coefficient during beam scanning.

[0115] The multiple antenna elements (output port 102B) may be configured as input / output sections of Butler matrix feed circuit 101 implemented using waveguides. By using the input / output sections of Butler matrix feed circuit 101 implemented using waveguides as the multiple antenna elements, the configuration of the multiple antenna elements can be simplified, and antenna device 300 can be provided with a simple configuration that can suppress an increase in the reflection coefficient during beam scanning.

[0116] Furthermore, the beams radiated from the multiple antenna elements (output port 102B) may have a reflection coefficient of −15 dB or less when the beam scanning angle is 60 degrees. This makes it possible to provide an antenna device 300 that can suppress an increase in the reflection coefficient of the beam even when the beam is steered at a large angle.

[0117] The antenna device 300M includes a Butler matrix feed circuit 101 realized with a waveguide and having a plurality of output sections, a bend structure 130 that bends the propagation direction of electromagnetic waves output from the plurality of output sections by 90 degrees, the bend structure 130 having a plurality of output ports 141 that radiate the electromagnetic waves in a radiation direction bent by 90 degrees from the propagation direction, and a matching layer 310 provided at intervals between the plurality of output ports 141 of the bend structure 130, the matching layer 310 having a substrate 311 made of a dielectric and a plurality of strips 312 provided on the substrate 311 and made of a conductor, the plurality of strips 312 being provided corresponding to the plurality of output ports 141, respectively, and the center of each output port overlaps with the corresponding strip 312 when viewed from the radiation direction. Therefore, when viewed from the radiation direction, each strip 312 is located at the center of the output port 141, and even if multiple strips 312 are arranged corresponding to multiple output ports 141, the coupling state between the strips 312 and the output ports 141 can be made equal at the center and ends of the antenna device 300M when viewed from the radiation direction (z direction).

[0118] Therefore, it is possible to provide the antenna device 300M that can suppress an increase in the reflection coefficient during beam scanning. Furthermore, since the antenna device 300M includes the bend structure 130, it is possible to bend the propagation direction of the electromagnetic waves output from the Butler matrix feed circuit 101 and output the waves.

[0119] Second Embodiment Next, a second embodiment of the present disclosure will be described. In the second embodiment, a cross-crossing directional coupler having a radiation structure will be described. The cross-crossing directional coupler of the second embodiment can be used in the bend structure 130 described above. FIG. 12 is a perspective view showing a configuration example of the cross-crossing directional coupler according to the second embodiment. FIG. 13 is a cross-sectional view taken along the line XVII-XVII in FIG. 12. FIG. 14 is a cross-sectional view taken along the line XVIII-XVIII in FIG. 12. FIG. 15 is a top view illustrating the configuration of each waveguide. Note that the cross-crossing directional coupler 3 having a radiation structure according to this embodiment differs from the cross-crossing directional coupler 1 described in the first embodiment in that it does not include the third waveguide 13. Other configurations are similar to those of the cross-crossing directional coupler 1 described in the first embodiment, and therefore, the same components are denoted by the same reference numerals, and redundant description will be omitted as appropriate.

[0120] 12 to 14, the cross-shaped directional coupler 3 according to this embodiment includes a first waveguide 11 and a second waveguide 12. The first and second waveguides 11 and 12 are stacked in the z-axis direction.

[0121] 13 , the first waveguide 11 has a first port P1 at one end in the waveguiding direction (the negative x-axis direction) and a third port P3 at the other end in the waveguiding direction (the positive x-axis direction). The second waveguide 12 has a second port P2 at one end in the waveguiding direction (the negative x-axis direction), and an end 17 opposite to the second port P2 is short-circuited. The second waveguide 12 is disposed below the first waveguide 11.

[0122] 13 and 14, a first slot SL1 is provided between the first waveguide 11 and the second waveguide 12. A second slot SL2 is provided on the surface of the first waveguide 11 opposite to the second waveguide 12 side (the surface on the positive side in the z-axis direction).

[0123] 14 and 15 , the first slot SL1 and the second slot SL2 are disposed on the lower and upper surfaces of the first waveguide 11 at the center in the width direction (y-axis direction) of the first waveguide 11. That is, as shown in Fig. 15 , the first slot SL1 and the second slot SL2 are provided symmetrically along the central axis C1 of the first waveguide 11.

[0124] 14 and 15, the first slot SL1 is disposed on the upper surface of the second waveguide 12, offset by a predetermined distance D1 from the center of the second waveguide 12 in the width direction (y-axis direction). That is, as shown in Fig. 15, the first slot SL1 is disposed offset by the distance D1 from the central axis C2 of the second waveguide 12. The first slot SL1 and the second slot SL2 overlap when viewed from the z-axis direction.

[0125] In this embodiment, the first and second waveguides 11 and 12 can be configured using rectangular parallelepiped waveguides. Note that the configurations of the first and second waveguides 11 and 12 are the same as those described in the first embodiment, so a duplicated description will be omitted.

[0126] The first slot SL1 and the second slot SL2 can be configured by forming holes in the first and second waveguides 11, 12. Specifically, the first slot SL1 can be configured by partially cutting out the bottom surface of the first waveguide 11 and the top surface of the second waveguide 12 to form a hole. The second slot SL2 can be configured by partially cutting out the top surface of the first waveguide 11 to form a hole. The configurations of the first and second slots SL1, SL2 are the same as those described in the first embodiment, so repeated description will be omitted.

[0127] In the cross-cross directional coupler 3 according to this embodiment, the second waveguide 12 and a space 50 (see FIGS. 13 and 14 ) on the positive side of the first waveguide 11 in the z-axis direction are coupled to each other via the first slot SL1, the first waveguide 11, and the second slot SL2. In other words, the second waveguide 12 and the space 50 are coupled to the first slot SL1 and the second slot SL2, and are also coupled to each other via the first waveguide 11. Here, the space 50 on the positive side of the first waveguide 11 in the z-axis direction is a space that is conveniently illustrated for the sake of explanation, and in reality, the space is not particularly limited on the positive side of the first waveguide 11 in the z-axis direction.

[0128] Therefore, the electromagnetic wave (output signal) supplied to the second port P2 of the second waveguide 12 passes through the first slot SL1, the first waveguide 11, and the second slot SL2, and is radiated from the second slot SL2 into the space 50 on the positive side of the first waveguide 11 in the z-axis direction.

[0129] That is, in the first waveguide 11, the first slot SL1 and the second slot SL2 are provided symmetrically along the central axis C1 of the first waveguide 11. Therefore, no potential difference is generated in the TE10 mode of the first waveguide 11, and therefore the first waveguide 11 is not coupled to the first slot SL1 or the second slot SL2. Therefore, the electromagnetic wave supplied to the first port P1 of the first waveguide 11 is output from the third port P3 of the first waveguide 11.

[0130] On the other hand, the first slot SL1 and the second slot SL2 are offset by a distance D1 from the central axis C2 of the second waveguide 12. In other words, when the second waveguide 12 is used as a reference, the first slot SL1 and the second slot SL2 are arranged asymmetrically with respect to the central axis C2. Therefore, the second waveguide 12 and the space 50 on the positive side of the z-axis direction of the first waveguide 11 are coupled to the first slot SL1 and the second slot SL2, and are also coupled to each other via the first waveguide 11. At this time, because the first slot SL1 and the second slot SL2 are arranged at the center with respect to the first waveguide 11, the second waveguide 12 is not coupled to the first waveguide 11. Therefore, the electromagnetic waves supplied to the second port P2 of the second waveguide 12 pass through the first slot SL1, the first waveguide 11, and the second slot SL2, and are radiated from the second slot SL2 into the space 50 on the positive side of the first waveguide 11 in the z-axis direction.

[0131] In this embodiment, the predetermined distance (offset distance) D1 can be determined arbitrarily depending on the design of the cross-cross directional coupler 3. That is, the offset distance D1 can be any distance so long as the second waveguide 12 is coupled to the first slot SL1 and the second slot SL2 and the first waveguide 11 is not coupled to the first slot SL1 and the second slot SL2. Here, "the first waveguide 11 is not coupled to the first slot SL1 and the second slot SL2" also includes the case where the first waveguide 11 is weakly coupled to the first slot SL1 and the second slot SL2. That is, as long as it does not significantly affect the design of the cross-cross directional coupler 3, the case where the first waveguide 11 is weakly coupled to the first slot SL1 and the second slot SL2 may also be included.

[0132] 16 is a graph showing the simulation results of the cross-cross directional coupler according to this embodiment. The simulation results shown in Fig. 16 show the frequency characteristics of the S parameters of the cross-cross directional coupler when the design frequency is 120 GHz and the relative dielectric constant inside each waveguide and each slot is 3.6.

[0133] Here, S11 indicates a signal reflected to the first port P1 when a signal is input from the first port P1. S12 indicates a signal passing through the first port P2 when a signal is input from the second port P1. S22 indicates a signal reflected to the second port P2 when a signal is input from the second port P2. S31 indicates a signal passing through the third port P3 when a signal is input from the first port P1. S32 indicates a signal passing through the third port P3 when a signal is input from the second port P2. S ＦＰ１，２ indicates a signal radiated from the second slot SL2 to the space 50 on the positive side in the z-axis direction of the first waveguide 11 when a signal is input from the second port P2. ＦＰ１，１ indicates a signal radiated from the second slot SL2 into the space 50 on the positive side in the z-axis direction of the first waveguide 11 when a signal is input from the first port P1.

[0134] As shown in Figure 16, S11 was -20 dB or less over a wide band. This is because the first slot SL1 and the second slot SL2 were located at the center of the first waveguide 11, and the influence of the first slot SL1 and the second slot SL2 was small. S22 was -10 dB or less near 120 GHz. S31 was -0.1 dB or more over a wide band, and the transmission characteristics from the first port P1 to the third port P3 were good.

[0135] S ＦＰ１，２ was -1 dB or more over a wide band, and the transmission characteristics from the second port P2 to the space 50 on the positive side in the z-axis direction of the first waveguide 11 were good. ＦＰ１，１ was −28 dB or less, and the isolation between the ports, that is, the isolation between the first port P1 and the second port P2, and the isolation between the first port P1 and the space 50 on the positive side of the first waveguide 11 in the z-axis direction, were good.

[0136] As described above, this embodiment can provide a cross-cross directional coupler 3 that has good transmission characteristics between the first port P1 and the third port P3 and good transmission characteristics between the second port P2 and the space 50 on the positive side in the z-axis direction of the first waveguide 11. Therefore, this embodiment can realize a cross-cross directional coupler, and can radiate an electromagnetic wave (output signal) supplied to the second port P2 of the second waveguide 12 from the second slot SL2 into the space 50 on the positive side in the z-axis direction of the first waveguide 11.

[0137] For example, by using the cross-crossing directional coupler 3 according to this embodiment on the output side of the bend structure 130 shown in Fig. 13, it is possible to radiate the output signal into the space 50 on the positive side in the z-axis direction of the first waveguide 11. Specifically, the cross-crossing directional coupler 3 according to this embodiment is used as the cross-crossing directional couplers 1c, 1e, and 1f arranged on the output side of the bend structure 130 shown in Fig. 13. With this configuration, it is possible to radiate the output signal from the output ports V2 to V4 into the space 50 on the positive side in the z-axis direction of the first waveguide 11, without providing separate antennas for the cross-crossing directional couplers 1c, 1e, and 1f.

[0138] <Embodiment 3> Next, a third embodiment of the present disclosure will be described. In the third embodiment, a cross-crossing directional coupler having a four-layer structure will be described. The cross-crossing directional coupler of the third embodiment can be used in the bend structure 130 described above. FIG. 17 is a perspective view showing a configuration example of the cross-crossing directional coupler according to the third embodiment. FIG. 18 is a cross-sectional view taken along the section line XXII-XXII in FIG. 17. FIG. 19 is a cross-sectional view taken along the section line XXIII-XXIII in FIG. 17. FIG. 20 is a top view illustrating the configuration of each waveguide. Note that the cross-crossing directional coupler 4 according to this embodiment differs from the cross-crossing directional coupler 1 described in the first embodiment in that it further includes a fourth waveguide 41. Other configurations are similar to those of the cross-crossing directional coupler 1 described in the first embodiment, and therefore, the same components are denoted by the same reference numerals, and redundant description will be omitted as appropriate.

[0139] 17 to 19 , the cross-cross directional coupler 4 according to this embodiment includes a first waveguide 11, a second waveguide 12, a third waveguide 13, and a fourth waveguide 41. The first to fourth waveguides 11 to 13, 41 are stacked in the z-axis direction in the order of the second waveguide 12, the first waveguide 11, the fourth waveguide 41, and the third waveguide 13. In other words, the cross-cross directional coupler 4 according to this embodiment has a configuration in which the fourth waveguide 41 is provided between the first waveguide 11 and the third waveguide 13 of the cross-cross directional coupler 1 described in the first embodiment.

[0140] As shown in FIG. 18 , the first waveguide 11 has a first port P1 at one end in the waveguiding direction (negative side in the x-axis direction) and a third port P3 at the other end in the waveguiding direction (positive side in the x-axis direction). The second waveguide 12 has a second port P2 at one end in the waveguiding direction (negative side in the x-axis direction), and an end 17 opposite the second port P2 is short-circuited. The second waveguide 12 is disposed below the first waveguide 11. The fourth waveguide 41 has a fifth port P5 at one end in the waveguiding direction (negative side in the x-axis direction) and a sixth port P6 at the other end in the waveguiding direction (positive side in the x-axis direction). The fourth waveguide 41 is disposed above the first waveguide 11. The third waveguide 13 has a fourth port P4 at one end in the waveguiding direction (positive side in the x-axis direction), and an end 18 opposite the fourth port P4 is short-circuited. The third waveguide 13 is disposed above the fourth waveguide 41 .

[0141] 18 and 19 , a first slot SL1 is provided between the first waveguide 11 and the second waveguide 12. A second slot SL2 is provided between the first waveguide 11 and the fourth waveguide 41. A third slot SL3 is provided between the fourth waveguide 41 and the third waveguide 13.

[0142] 19 and 20 , the first slot SL1 and the second slot SL2 are disposed at the center of the width direction (y-axis direction) of the first waveguide 11 on the lower and upper surfaces thereof. That is, as shown in Fig. 20 , the first slot SL1 and the second slot SL2 are disposed symmetrically along the central axis C1 of the first waveguide 11. Furthermore, the second slot SL2 and the third slot SL3 are disposed at the center of the width direction (y-axis direction) of the fourth waveguide 41 on the lower and upper surfaces thereof. That is, as shown in Fig. 20 , the second slot SL2 and the third slot SL3 are disposed symmetrically along the central axis C1 of the fourth waveguide 41.

[0143] As shown in Figures 19 and 20, the first slot SL1, the second slot SL2, and the third slot SL3 are disposed on the upper surface of the second waveguide 12 and the lower surface of the third waveguide 13, offset by a predetermined distance D1 from the center of the second waveguide 12 and the third waveguide 13 in the width direction (y-axis direction). That is, as shown in Figure 20, the first slot SL1 is disposed offset by the distance D1 from the central axis C2 of the second waveguide 12. Furthermore, the third slot SL3 is disposed offset by the distance D1 from the central axis C2 of the third waveguide 13. Note that the central axis C2 of the second waveguide 12 and the central axis C2 of the third waveguide 13 overlap when viewed from the z-axis direction. Furthermore, the first slot SL1 to the third slot SL3 overlap when viewed from the z-axis direction.

[0144] 19 , for example, the positions of the second waveguide 12 and the third waveguide 13 in the y-axis direction are aligned, the positions of the first waveguide 11 and the fourth waveguide 41 in the y-axis direction are aligned, and the positions of the first waveguide 11 and the fourth waveguide 41 in the y-axis direction are shifted toward the positive side in the y-axis direction with respect to the second waveguide 12 and the third waveguide 13. With this configuration, the positions of the first slot SL1 to the third slot SL3 can be offset by a predetermined distance D1 from the center of the second waveguide 12 and the third waveguide 13 in the width direction (y-axis direction).

[0145] In this embodiment, the first to fourth waveguides 11 to 13, 41 can be configured using rectangular parallelepiped waveguides. The fourth waveguide 41 can be configured in the same manner as the first waveguide 11. Note that the configurations of the first to fourth waveguides 11 to 13, 41 are the same as those described in the first embodiment, and therefore, redundant description will be omitted.

[0146] The first slot SL1 to the third slot SL3 can be configured by forming holes in the first to fourth waveguides 11 to 13, 41. Specifically, the first slot SL1 can be configured by partially cutting out the bottom surface of the first waveguide 11 and the top surface of the second waveguide 12 to form a hole. The second slot SL2 can be configured by partially cutting out the top surface of the first waveguide 11 and the bottom surface of the fourth waveguide 41 to form a hole. The third slot SL3 can be configured by partially cutting out the top surface of the fourth waveguide 41 and the bottom surface of the third waveguide 13 to form a hole. The configurations of the first slot SL1 to the third slot SL3 are the same as those described in the first embodiment, so repeated description will be omitted.

[0147] In the cross-cross directional coupler 4 according to this embodiment, the second waveguide 12 and the third waveguide 13 are coupled to each other via the first slot SL1, the first waveguide 11, the second slot SL2, the fourth waveguide 41, and the third slot SL3. In other words, the second waveguide 12 and the third waveguide 13 are coupled to the first slot SL1 and the third slot SL3, and are also coupled to each other via the first waveguide 11, the second slot SL2, and the fourth waveguide 41.

[0148] Therefore, the electromagnetic wave supplied to the second port P2 of the second waveguide 12 propagates through the first slot SL1, the first waveguide 11, the second slot SL2, the fourth waveguide 41, and the third slot SL3 to the third waveguide 13 and is output from the fourth port P4 of the third waveguide 13. Furthermore, the electromagnetic wave supplied to the first port P1 of the first waveguide 11 is output from the third port P3 of the first waveguide 11. Furthermore, the electromagnetic wave supplied to the fifth port P5 of the fourth waveguide 41 is output from the sixth port P6 of the fourth waveguide 41.

[0149] That is, in the first waveguide 11, the first slot SL1 and the second slot SL2 are provided symmetrically along the central axis C1 of the first waveguide 11. Therefore, no potential difference is generated in the TE10 mode of the first waveguide 11, and therefore the first waveguide 11 is not coupled to the first slot SL1 or the second slot SL2. Therefore, the electromagnetic wave supplied to the first port P1 of the first waveguide 11 is output from the third port P3 of the first waveguide 11.

[0150] Similarly, in the fourth waveguide 41, the second slot SL2 and the third slot SL3 are provided symmetrically along the central axis C1 of the fourth waveguide 41. Therefore, no potential difference is generated in the TE10 mode of the fourth waveguide 41, and therefore the fourth waveguide 41 is not coupled to the second slot SL2 or the third slot SL3. Therefore, an electromagnetic wave supplied to the fifth port P5 of the fourth waveguide 41 is output from the sixth port P6 of the fourth waveguide 41.

[0151] Meanwhile, the first slot SL1 and the third slot SL3 in the second waveguide 12 and the third waveguide 13 are arranged offset by a distance D1 from the central axis C2 of the second waveguide 12 and the third waveguide 13. In other words, the first slot SL1 and the third slot SL3 in the second waveguide 12 and the third waveguide 13 are arranged asymmetrically with respect to the central axis C2. In this embodiment, the second slot SL1 is also arranged asymmetrically with respect to the central axis C2, and the first slot SL1 to the third slot SL3 are arranged so as to overlap when viewed from the z-axis direction.

[0152] Therefore, the second waveguide 12 and the third waveguide 13 are coupled to the first slot SL1 and the third slot SL3, and are also coupled to each other via the first waveguide 11, the second slot SL2, and the fourth waveguide 41. At this time, since the first slot SL1 and the second slot SL2 are disposed centrally with respect to the first waveguide 11, the second waveguide 12 and the third waveguide 13 are not coupled to the first waveguide 11. Similarly, since the second slot SL2 and the third slot SL3 are disposed centrally with respect to the fourth waveguide 41, the second waveguide 12 and the third waveguide 13 are not coupled to the fourth waveguide 41. Therefore, the electromagnetic wave supplied to the second port P2 of the second waveguide 12 propagates through the first slot SL1, the first waveguide 11, the second slot SL2, the fourth waveguide 41, and the third slot SL3 to the third waveguide 13 and is output from the fourth port P4 of the third waveguide 13. Here, the path between the second port P2 and the fourth port P4 is a path that passes perpendicularly through the first waveguide 11 and the fourth waveguide 41.

[0153] In this embodiment, the predetermined distance (offset distance) D1 can be determined arbitrarily depending on the design of the cross-cross directional coupler 4. That is, the offset distance D1 can be any distance such that the second waveguide 12 and the third waveguide 13 are coupled to the first slot SL1 and the third slot SL3, the first waveguide 11 is not coupled to the first slot SL1 and the second slot SL2, and the fourth waveguide 41 is not coupled to the second slot SL2 and the third slot SL3. Here, "the first waveguide 11 is not coupled to the first slot SL1 and the second slot SL2" also includes the case where the first waveguide 11 is weakly coupled to the first slot SL1 and the second slot SL2. That is, as long as it does not significantly affect the design of the cross-cross directional coupler 1, the case where the first waveguide 11 is weakly coupled to the first slot SL1 and the second slot SL2 may also be included. The same applies to the case where "the fourth waveguide 41 is not coupled to the second slot SL2 and the third slot SL3."

[0154] As an example, the predetermined distance (offset distance) D1 is preferably in the range of 1% to 50% of the width (distance in the y-axis direction) of the second waveguide 12 and the third waveguide 13, more preferably in the range of 1% to 35%, and even more preferably in the range of 5% to 25%.

[0155] 20 shows an example in which the first slot SL1 to the third slot SL3 are rectangular in shape extending in the waveguide direction (x-axis direction). However, in this embodiment, the first slot SL1 to the third slot SL3 may be rectangular in shape extending in the width direction of the waveguide (y-axis direction), or may be cross-shaped. In other words, the first slot SL1 to the third slot SL3 may be any shape as long as the second waveguide 12 and the third waveguide 13 are coupled to the first slot SL1 to the third slot SL3.

[0156] The cross-shaped directional coupler 4 according to this embodiment is also capable of propagating electromagnetic waves in opposite directions from each port. That is, when an electromagnetic wave is supplied to the third port P3 of the first waveguide 11, the electromagnetic wave is output from the first port P1 of the first waveguide 11. When an electromagnetic wave is supplied to the sixth port P6 of the fourth waveguide 41, the electromagnetic wave is output from the fifth port P5 of the fourth waveguide 41. When an electromagnetic wave is supplied to the fourth port P4 of the third waveguide 13, the electromagnetic wave propagates to the second waveguide 12 via the third slot SL3, the fourth waveguide 41, the second slot SL2, the first waveguide 11, and the first slot SL1, and is output from the second port P2 of the second waveguide 12.

[0157] 21 is a graph showing the simulation results of the cross-cross directional coupler according to this embodiment. The simulation results shown in Fig. 21 show the frequency characteristics of the S parameters of the cross-cross directional coupler when the design frequency is 120 GHz and the relative dielectric constant inside each waveguide and each slot is 3.6.

[0158] Here, S55 indicates a signal reflected at the fifth port P5 when a signal is input from the fifth port P5. S51 indicates a signal passing through the fifth port P5 when a signal is input from the first port P1. S22 indicates a signal reflected at the second port P2 when a signal is input from the second port P2. S31 indicates a signal passing through the third port P3 when a signal is input from the first port P1. S63 indicates a signal passing through the sixth port P6 when a signal is input from the third port P3. S42 indicates a signal passing through the fourth port P4 when a signal is input from the second port P2. S56 indicates a signal passing through the fifth port P5 when a signal is input from the sixth port P6. Due to structural symmetry, S55 = S66, S51 = S63, and S22 = S44.

[0159] As shown in FIG. 21, S55 was −35 dB or less across a wide bandwidth. This is because the second slot SL2 and the third slot SL3 were located at the center of the fourth waveguide 41, and the influence of the second slot SL2 and the third slot SL3 was small. S22 was −15 dB or less across a wide bandwidth. S31 was −0.1 dB or more across a wide bandwidth, and the transmission characteristics from the first port P1 to the third port P3 were good. S56 was −0.1 dB or more across a wide bandwidth, and the transmission characteristics from the fifth port P5 to the sixth port P6 were good. S42 was −0.2 dB or more across a wide bandwidth, and the transmission characteristics from the second port P2 to the fourth port P4 were good. Furthermore, S51 and S63 were −25 dB or less, and the isolation between ports, that is, the isolation between the first port P1 and the fifth port P5, and the isolation between the third port P3 and the sixth port P6, was good.

[0160] As described above, this embodiment can provide a cross-cross directional coupler 4 that has good transmission characteristics between the first port P1 and the third port P3, and between the fifth port P5 and the sixth port P6, and also has good transmission characteristics between the second port P2 and the fourth port P4.

[0161] For example, by using the cross-cross directional coupler 4 according to this embodiment in the bend structure 130 shown in Fig. 13, the configuration of the bend structure 130 can be simplified. Specifically, the two cross-cross directional couplers 1a and 1b of the bend structure 130 shown in Fig. 13 can be replaced with the cross-cross directional coupler 4 according to this embodiment. In other words, since the two cross-cross directional couplers 1a and 1b can be replaced with one cross-cross directional coupler 4, the configuration of the bend structure 130 can be simplified.

[0162] In the configuration example described above, a cross-crossing directional coupler having a four-layer structure has been described. That is, a cross-crossing directional coupler with three inputs and three outputs has been described. However, in this embodiment, an additional waveguide may be added between the first waveguide 11 and the fourth waveguide 41 to increase the number of input ports and output ports of the cross-crossing directional coupler. Specifically, an additional n (n is an integer equal to or greater than 1) waveguides may be added between the first waveguide 11 and the fourth waveguide 41 to form a cross-crossing directional coupler with (n+3) inputs and (n+3) outputs.

[0163] In this case, the additional waveguide can be configured in the same manner as the first waveguide 11 and the fourth waveguide 41. Specifically, the position of the slot provided in the additional waveguide can be the same as the position of the second slot SL2 in the first waveguide 11 and the fourth waveguide 41. In other words, the position of the slot provided in the additional waveguide can be a position that overlaps with the second slot SL2 when viewed from the z-axis direction.

[0164] Next, another configuration example of the cross-cross directional coupler according to this embodiment will be described. FIG. 22 is a top view illustrating another configuration example of each waveguide of the cross-cross directional coupler according to the third embodiment. In the cross-cross directional coupler according to this embodiment, a recess 45 may be formed on the side surface of the first waveguide 11. The configuration example shown in FIG. 22 illustrates a configuration example in which four recesses 45 are formed on the side surface of the first waveguide 11. The positions at which the recesses 45 are formed can be determined depending on the state of the electromagnetic wave propagating inside the first waveguide 11. A recess 46 may also be formed on the side surface of the fourth waveguide 41. When the recesses 45 and 46 are formed on the side surfaces of the first waveguide 11 and the fourth waveguide 41, respectively, as in the configuration example shown in FIG. 22, the state of the electromagnetic wave propagating inside the first waveguide 11 and the fourth waveguide 41 can be accurately adjusted.

[0165] <Fourth Embodiment> Next, a fourth embodiment of the present disclosure will be described. Fig. 23 is a perspective view showing a configuration example of a cross-cross directional coupler according to the fourth embodiment. The cross-cross directional coupler according to the fourth embodiment can be used in the bend structure 130 described above. The cross-cross directional coupler 5 according to the fourth embodiment has a configuration in which the cross-cross directional coupler 3 described in the second embodiment and the cross-cross directional coupler 4 described in the third embodiment are combined. That is, the cross-cross directional coupler 5 according to the present embodiment has a configuration in which a radiation structure is provided in the cross-cross directional coupler 4 according to the third embodiment. Note that the cross-cross directional coupler 5 according to the present embodiment differs from the cross-cross directional coupler 4 described in the third embodiment in that it does not include the third waveguide 13. The rest of the configuration is the same as the cross-cross directional coupler 4 described in the third embodiment, so the same components are denoted by the same reference numerals, and duplicated descriptions will be omitted as appropriate.

[0166] 23 , the cross-cross directional coupler 5 according to this embodiment includes a first waveguide 11, a second waveguide 12, and a fourth waveguide 41. These waveguides are stacked in the z-axis direction in the order of the second waveguide 12, the first waveguide 11, and the fourth waveguide 41. In other words, the cross-cross directional coupler 5 according to this embodiment has a configuration in which the third waveguide 13 is removed from the cross-cross directional coupler 4 described in the third embodiment.

[0167] As shown in Figure 23, the first waveguide 11 has a first port P1 at one end in the waveguiding direction (negative side in the x-axis direction) and a third port P3 at the other end in the waveguiding direction (positive side in the x-axis direction). The second waveguide 12 has a second port P2 at one end in the waveguiding direction (negative side in the x-axis direction), and an end 17 opposite the second port P2 is short-circuited. The second waveguide 12 is disposed below the first waveguide 11. The fourth waveguide 41 has a fifth port P5 at one end in the waveguiding direction (negative side in the x-axis direction) and a sixth port P6 at the other end in the waveguiding direction (positive side in the x-axis direction). The fourth waveguide 41 is disposed above the first waveguide 11.

[0168] A first slot SL1 is provided between the first waveguide 11 and the second waveguide 12. A second slot SL2 is provided between the first waveguide 11 and the fourth waveguide 41. A third slot SL3 is provided on the top surface of the fourth waveguide 41.

[0169] In the cross-cross directional coupler 5 according to this embodiment, the second waveguide 12 is coupled to the space on the positive side in the z-axis direction of the fourth waveguide 41 via the first slot SL1, the first waveguide 11, the second slot SL2, the fourth waveguide 41, and the third slot SL3. Thus, an electromagnetic wave (output signal) supplied to the second port P2 of the second waveguide 12 passes through the first slot SL1, the first waveguide 11, the second slot SL2, the fourth waveguide 41, and the third slot SL3, and is radiated from the third slot SL3 into the space on the positive side in the z-axis direction of the fourth waveguide 41.

[0170] The cross-cross directional coupler 5 according to this embodiment having the above configuration can provide a cross-cross directional coupler that has good transmission characteristics between the first port P1 and the third port P3, and between the fifth port P5 and the sixth port P6, and that also has good transmission characteristics between the second port P2 and the space on the positive side of the z-axis direction of the first waveguide 11. Therefore, this embodiment realizes a cross-cross directional coupler, and can radiate an electromagnetic wave (output signal) supplied to the second port P2 of the second waveguide 12 from the third slot SL3 into the space on the positive side of the z-axis direction of the fourth waveguide 41.

[0171] For example, by using the cross-crossing directional coupler 5 according to this embodiment on the output side of the bend structure 130 shown in Fig. 13 , an output signal can be radiated into space on the positive side in the z-axis direction of the fourth waveguide 41. Specifically, by replacing the two cross-crossing directional couplers 1d and 1e arranged on the output side of the bend structure 130 shown in Fig. 13 with the cross-crossing directional coupler 5 according to this embodiment, the two cross-crossing directional couplers 1d and 1e can be replaced with one cross-crossing directional coupler 5. This simplifies the configuration of the bend structure 130. Furthermore, an output signal can be radiated from the output port V3 into space on the positive side in the z-axis direction of the fourth waveguide 41 without providing a separate antenna to the cross-crossing directional coupler.

[0172] In the configuration example described above, a three-input, three-output cross-cross directional coupler has been described. However, in this embodiment, an additional waveguide may be added between the first waveguide 11 and the fourth waveguide 41 to increase the number of input ports and output ports of the cross-cross directional coupler. Specifically, an additional n (n is an integer equal to or greater than 1) waveguides may be added between the first waveguide 11 and the fourth waveguide 41 to configure a (n+3) input, (n+3) output cross-cross directional coupler.

[0173] In this case, the additional waveguide can be configured in the same manner as the first waveguide 11 and the fourth waveguide 41. Specifically, the position of the slot provided in the additional waveguide can be the same as the position of the second slot SL2 in the first waveguide 11 and the fourth waveguide 41. In other words, the position of the slot provided in the additional waveguide can be a position that overlaps with the second slot SL2 when viewed from the z-axis direction.

[0174] Furthermore, the results of the following simulations will be explained.

[0175] <Simulation Results of Admittance Locus> Fig. 24 is a diagram showing an example of a simulation model (periodic boundary model) of the unit structure of the Butler matrix feed circuit 101 and the unit structure of the matching layer 310. The simulation model shown in Fig. 24 is the same as the simulation model of the unit structure of the Butler matrix feed circuit 101 and the unit structure of the matching layer 310 shown in Fig. 3C. Using the simulation model shown in Fig. 24, the admittance locus between the input port 102A and the surface of the matching layer 310 on the +x direction side of the substrate 311 was calculated. The surface of the matching layer 310 on the +x direction side of the substrate 311 was set as the phase reference plane of the admittance locus.

[0176] In a simulation model of the Butler matrix feed circuit 101 unit structure and the matching layer 310 unit structure, the y-direction length a of the waveguide of the Butler matrix feed circuit 101 was set to 1.000 mm, and the z-direction length b of the waveguide was set to 0.370 mm. The y-direction length Py of one unit structure of the substrate 311 was set to 1.200 mm, and the z-direction length Pz was set to 0.624 mm. The distance Cx of the two posts 102B2 from the output port 102B was set to 0.850 mm, and the distance Px of the matching layer 310 from the output port 102B in the +x direction was set to 0.490 mm. The length Sz of the strip 312 was set to 0.400 mm, and the width Sy of the strip 312 was set to 0.127 mm. Note that, when viewed in the yz plane, the center of the strip 312 was aligned with the center 102B1 of the output port 102B. The frequency of the input signal was set to 120 GHz.

[0177] In addition, to confirm the function of the Butler matrix feed circuit 101 as a waveguide, a simulation model in which the matching layer 310 is omitted and a simulation model in which the matching layer 310 is used alone were used.

[0178] The simulation model omitting the matching layer 310 is a simulation model obtained by omitting the matching layer 310 from the simulation model shown in Fig. 24, and is a simulation model of the Butler matrix feed circuit 101 alone. Hereinafter, this will be referred to as a simulation model of the Butler matrix feed circuit 101 alone. The simulation model of the matching layer 310 alone is a simulation model that includes only the matching layer 310 of the simulation model shown in Fig. 24.

[0179] In the simulation, the locus of admittance in the E-plane and the H-plane was calculated when the direction of the beam output from the output port 102B was changed. To define the beam direction, angles θs and φs shown in FIG. 24 were used. The angle θs is the angle with respect to the +x direction, and the direction indicated by the arrow is the positive angle. The angle θs corresponds to the scanning angle of the beam. The angle φs is the angle with respect to the +y direction, and the direction indicated by the arrow is the positive angle. When the angle φs is 0 degrees, the angle θs is the angle with respect to the +x direction in the xy plane, and when the angle φs is 90 degrees, the angle θs is the angle with respect to the +x direction in the xz plane.

[0180] The reference plane for the phase of the beam was set on the surface of the matching layer 310 on the +x direction side of the substrate 311. The E plane is a plane parallel to the xz plane, and the H plane is a plane parallel to the xy plane.

[0181] 25 is a diagram showing an example of the calculation results of the admittance locus in a simulation model of the Butler matrix feed circuit 101 alone. The admittance locus on the E-plane is shown by a solid line, and the admittance locus on the H-plane is shown by a dashed line.

[0182] An input signal was input to input port 102A of Butler matrix feeding circuit 101, and a phase difference was applied to the radio waves emitted from output port 102B, thereby performing beam scanning so as to set an angle with respect to the +x direction, and the admittance was calculated.

[0183] To calculate the locus of admittance on the E-plane, the angle φs was set to 90 degrees and the angle θs was changed from 0 to 70 degrees. As a result, it was confirmed that the admittance changed as if an equal conductance circle was inverted around the center, and that reflection of the input power occurred.

[0184] Furthermore, in order to calculate the locus of admittance on the H-plane, the angle φs was set to 0 degrees and the angle θs was changed from 0 degrees to 70 degrees. As a result, it was confirmed that the admittance changed away from the center, and that beam reflection occurred.

[0185] As described above, it was confirmed that the Butler matrix feed circuit 101 alone caused large reflections.

[0186] 26 is a diagram showing an example of the calculation results of the admittance locus in a simulation model of the matching layer 310 alone. The admittance locus on the E-plane is shown by a solid line, and the admittance locus on the H-plane is shown by a dashed line.

[0187] When a beam was made incident on the matching layer 310, the beam was scanned so as to be angled with respect to the +x direction, and the admittance of the matching layer 310 alone was calculated.

[0188] To calculate the admittance locus on the E-plane, the angle φs was set to 90 degrees and the angle θs was changed from 0 to 70 degrees, and it was confirmed that the admittance changed along an equal conductance circle around the center, showing characteristics that are the exact opposite of the admittance locus on the E-plane shown in Figure 25. The admittance locus being the exact opposite means that the characteristics are inverted relative to the equal conductance circle.

[0189] Furthermore, in order to calculate the admittance locus on the H-plane, the angle φs was set to 0 degrees and the angle θs was varied from 0 degrees to 70 degrees. The result was a locus of admittance on the H-plane shown in Figure 25 that was inverted with respect to the horizontal axis.

[0190] As described above, it was confirmed that the simulation model of the matching layer 310 alone yields an admittance locus with characteristics similar to the inverse of the admittance locus of the simulation model of the Butler matrix feed circuit 101 alone.

[0191] <Calculation results of a simulation model of the unit structure of the Butler matrix feed circuit 101 and the unit structure of the matching layer 310> Figure 27 is a diagram showing an example of the calculation results of the admittance locus in a simulation model of the unit structure of the Butler matrix feed circuit 101 and the unit structure of the matching layer 310. The admittance locus on the E-plane is shown by a solid line, and the admittance locus on the H-plane is shown by a dashed line.

[0192] An input signal was input to input port 102A of Butler matrix feeding circuit 101, and a phase difference was applied to the radio waves emitted from output port 102B, thereby performing beam scanning so as to set an angle with respect to the +x direction, and the admittance was calculated.

[0193] To calculate the admittance locus on the E-plane, the angle φs was set to 90 degrees and the angle θs was changed from 0 to 70 degrees, resulting in a characteristic in which the admittance change was small near the center. The admittance locus on the E-plane shown in Figure 25 and the admittance locus on the E-plane shown in Figure 26 were added together and canceled out, confirming that the beam reflection was small.

[0194] In addition, to calculate the admittance locus on the H-plane, the angle φs was set to 0 degrees and the angle θs was changed from 0 degrees to 70 degrees, and it was confirmed that the admittance changed along the conductance circle near the center and that the beam reflection was small. The admittance locus on the H-plane exhibited characteristics such that the admittance locus on the H-plane shown in Figure 25 and the admittance locus on the H-plane shown in Figure 26 were added together and canceled each other out.

[0195] As described above, in the simulation model of the unit structure of the Butler matrix feed circuit 101 and the unit structure of the matching layer 310, it was confirmed that reflection was small from the admittance loci on the E-plane and H-plane.

[0196] <Simulation results of reflection characteristics in a simulation model of the unit structure of the Butler matrix feed circuit 101 and the unit structure of the matching layer 310> Figure 28 is a diagram showing an example of the characteristics of the S11 parameter with respect to the beam scanning angle in a simulation model of the unit structure of the Butler matrix feed circuit 101 and the unit structure of the matching layer 310.

[0197] The S11 parameter represents the portion of the power input from the input port 102A that is returned to the input port 102A without being radiated from the output port 102B. The frequency of the input signal was set to 120 GHz. The angular characteristics of the S11 parameter obtained on the E-plane are shown by a solid line, and the angular characteristics of the S11 parameter obtained on the H-plane are shown by a dashed line.

[0198] 28, it was confirmed that reflection could be suppressed to -10 dB or less even when the beam scanning angle increased from 0 degrees to 70 degrees on both the E-plane and the H-plane. Therefore, it was confirmed that the antenna device 300 is capable of beam scanning in an excellent state with reduced reflection from an angle region with a small beam scanning angle to an angle region with a large beam scanning angle.

[0199] <Simulation Results of a One-Dimensional Antenna Device> Fig. 29A is a diagram showing an example of a simulation model of a one-dimensional antenna device. Fig. 29A shows a periodic boundary model extracted from an example of a simulation model of the unit structure of the Butler matrix feed circuit 101 and the unit structure of the matching layer 310. Fig. 29A only shows the reference symbols for the matching layer 310 and the substrate 311, but the strip 312 is located at the center of the surface on the −x direction side of the substrate 311 and extends in the z direction. The origin of the xyz coordinate system is located at the center of the surface on the −x direction side of the strip 312. Also, on the −x direction side of the strip 312, a through-hole and two posts 102B2 connecting the input port 102A and the output port 102B in the unit structure of the Butler matrix feed circuit 101 are shown.

[0200] The Butler matrix feed circuit 101 of the one-dimensional antenna device has, as an example, a 1 x 8 one-dimensional configuration in which the input ports 102A and output ports 102B are arranged eight in the y direction and one in the z direction. Also, the strips 312 of the matching layer 310 of the one-dimensional antenna device are arranged eight in the y direction and one in the z direction, corresponding to the eight output ports 102B in the 1 x 8 one-dimensional configuration.

[0201] When an analysis was performed on such a one-dimensionally arranged antenna device with boundary conditions set only at the end on the -y direction side and the end on the +y direction side, it was found that, unlike the two-dimensionally arranged antenna device 300 shown in Figures 1 and 2, some ingenuity was required to make the S11 parameter -10 dB when the beam scanning angle (θs) was in the range of 0 degrees to 70 degrees.

[0202] Here, the length in the z direction of the portion of substrate 311 that corresponds to one strip 312 is Pz. When the length in the z direction Pz of substrate 311 of matching layer 310 was increased without changing the length in the z direction of strip 312, a condition was found under which the S11 parameter became −10 dB or less. Since the value of the S11 parameter decreased when length Pz of substrate 311 was long, it is thought that when length Pz was short, the portions of substrate 311 on the −z direction side and +z direction side of strip 312 were shorter, thereby increasing the reflection at output port 102B. It is thought that by increasing length Pz of substrate 311, the portions of substrate 311 on the −z direction side and +z direction side of strip 312 became larger, thereby reducing the reflection at output port 102B.

[0203] 29B is a diagram showing an example of the characteristic of the S11 parameter with respect to the beam scanning angle θs in one periodic boundary model of the simulation model of the antenna device with a 1x8 one-dimensional arrangement. The S11 parameter represents the power that is input from input port 102A of one periodic boundary model of the simulation model of the antenna device with a 1x8 one-dimensional arrangement and returns to input port 102A without being radiated from output port 102B. The frequency of the input signal was set to 120 GHz.

[0204] When the length Sz of the strip 312 was set to 0.400 mm and the length Pz of the substrate 311 was set to 5 mm and the beam scanning angle θs was changed from 0 degrees to 70 degrees, the S11 parameter was −10 dB or less throughout the entire range of the beam scanning angle θs from 0 degrees to 70 degrees. As a result of fixing the length Sz of the strip 312 to 0.400 mm and changing the length Pz of the substrate 311, it was found that the S11 parameter was −10 dB or less when the ratio Sz / Pz of the length Sz to the length Pz was 0.05 or more and 1 or less.

[0205] <Simulation Results of a One-Dimensional Arrangement Antenna Apparatus Having a Parasitic Strip> Figures 30A and 30B are diagrams showing an example of a simulation model of a one-dimensional arrangement antenna apparatus having a parasitic strip. Figure 30A shows a periodic boundary model extracted from an example of a simulation model of the unit structure of the Butler matrix feed circuit 101 and the unit structure of the matching layer 310. Figure 30B shows a simulation model (8-element model) having a 1x8 one-dimensional arrangement configuration. Note that the space on the +x direction side of the substrate 311 was set under conditions such that no radio wave reflection occurs.

[0206] In Fig. 30A, reference numerals are shown only for the matching layer 310, the substrate 311, the strip 312, and the parasitic strip 312P, but similar to Fig. 29A, on the -x direction side of the strip 312, there are shown a through hole and two posts 102B2 connecting the input port 102A and the output port 102B in the unit structure of the Butler matrix feed circuit 101. In addition, Fig. 30B shows an eight-element model in which eight periodic boundary models shown in Fig. 30A are arranged in the y direction.

[0207] The one-dimensional antenna device having parasitic strips has a configuration in which, compared to the antenna device shown in Fig. 29A , one parasitic strip 312P is added to each of the −z direction side and +z direction side of each strip 312. Therefore, the periodic boundary model shown in Fig. 30A has three strips: the strip 312 and two parasitic strips 312P provided on the −z direction side and +z direction side of the strip 312.

[0208] The configuration of the strip 312 is the same as that described with reference to FIG. 3B, and therefore will not be described here.

[0209] The two parasitic strips 312P, like the strips 312, are provided on the surface on the −x direction side of the substrate 311. Like the strips 312, the parasitic strips 312P can be made of copper or aluminum, for example. When the strips 312 are provided on the surface on the +x direction side of the substrate 311, the parasitic strips 312P are preferably provided on the surface on the +x direction side of the substrate 311. Furthermore, when the strips 312 are provided on an inner layer of the substrate 311, the parasitic strips 312P are also preferably provided on an inner layer of the substrate 311.

[0210] The parasitic strip 312P extends parallel to the z-direction, for example, similar to the strip 312. All of the parasitic strips 312P in the eight-element model are parallel to one another. Similar to the strip 312, the parasitic strip 312P has a longitudinal direction extending in the z-direction and is a linear conductor layer in plan view. Similar to the strip 312, the parasitic strip 312P extends parallel to the polarization direction of the radio wave radiated from the strip 312.

[0211] Such a parasitic strip 312P is parasitic on the strip 312 located between the two parasitic strips 312P. In other words, in each periodic boundary model, the two parasitic strips 312P are electromagnetically coupled to the strip 312 located therebetween.

[0212] 31A is a diagram showing an example of the positional relationship between one output port 102B, the strip 312 corresponding to that output port 102B, and two parasitic strips 312P in the yz plane. In FIG. 31A, the outline of one output port 102B is shown by a dashed line as an example. Also shown is the center 102B1 of one output port 102B in the yz plane. Note that, as an example, the polarization direction of the radio wave at the output port 102B is the z direction, which is vertical polarization.

[0213] The parasitic strips 312P are provided one on each of the −z direction side and the +z direction side of the strip 312. The size of each parasitic strip 312P in the yz plane is equal to that of the strip 312. The position of each parasitic strip 312P in the y direction coincides with the position of the strip 312 in the y direction. The distance in the z direction between each parasitic strip 312P and the strip 312 is equal.

[0214] 31A, the pitch P312 between the strip 312 and the parasitic strip 312P is preferably 0.05 λe or more and 5 λe or less, where λe is the electrical length of a wavelength at the operating frequency of the Butler matrix feed circuit 101 as a waveguide. The pitch P312 is the distance between the center of the length of the strip 312 in the z direction and the center of the length of the parasitic strip 312P in the z direction.

[0215] As shown in Figure 31B, when both ends of the strip 312 in the z direction are located inside both ends of the output port 102B in the z direction, the end of the parasitic strip 312P on the -z direction side on the +z direction side and the end of the parasitic strip 312P on the +z direction side on the -z direction side may be arranged so as to be located inside the output port 102B when viewed from the yz plane.

[0216] Further, although the configuration described here has one parasitic strip 312P provided on the -z direction side and one on the +z direction side of each strip 312, the parasitic strip 312P may also be provided on either the -z direction side or the +z direction side of the strip 312.

[0217] The eight-element model shown in Figure 30B has a 1x8 one-dimensional configuration in which eight input ports 102A and output ports 102B are arranged in the y direction and one in the z direction. Corresponding to the eight output ports 102B in the 1x8 one-dimensional configuration, eight strips 312 are arranged in the y direction and one in the z direction, in a 1x8 one-dimensional configuration. In addition, one parasitic strip 312P is provided on each of the -z direction side and +z direction side of each strip 312.

[0218] <Simulation Results of Active S-Parameters in a One-Dimensional Arrangement Antenna Apparatus Having a Parasitic Strip> FIGS. 32A to 32D show examples of simulation results of frequency characteristics of active S-parameters in a one-dimensional arrangement antenna apparatus having a parasitic strip.

[0219] Active S-parameters were calculated when input signals with different phases were input to the eight input ports 102A of the eight-element model and the beam output from the output port 102B was scanned. Active S-parameters were calculated for each of the eight output ports 102B. The eight output ports 102B correspond to the input ports 102A, Port 1 to Port 8, shown in FIG. 30B, respectively. Below, the output ports 102B will also be referred to as Port 1 to Port 8. Port 1 is the port at the end on the -Y direction side, and Port 8 is the port at the end on the +y direction side.

[0220] The frequency characteristics of the active S-parameters S1 to S4 shown in Figures 32A to 32D are the frequency characteristics of the active S-parameters calculated for Ports 1 to 4 of the eight output ports 102B. The frequency characteristics of the active S-parameters calculated for Ports 5 to 8 are omitted here because they are symmetrical to the frequency characteristics of the active S-parameters calculated for Ports 1 to 4. The frequency of the input signal was set to 120 GHz.

[0221] The active S parameters were obtained by changing the phase difference Ψs of the input signal to the input ports 102A of Port 1 to Port 8 to 22.5 degrees, 67.5 degrees, 112.5 degrees, and 157.5 degrees. When the phase difference Ψs was 22.5 degrees, 67.5 degrees, 112.5 degrees, and 157.5 degrees, the beam scanning angle θs was 7.48 degrees, 22.98 degrees, 40.59 degrees, and 65.62 degrees, respectively. The pitch (center-to-center distance) in the y direction of the waveguides of the Butler matrix feed circuits 101 of Port 1 to Port 8 was 0.48λ. ０ λ ０ is the wavelength of a 120 GHz radio wave in free space.

[0222] As shown in Figure 32A, the frequency characteristics of the active S1 parameter obtained at Port 1 of output port 102B showed that when the phase difference Ψs was changed to 22.5 degrees, 67.5 degrees, 112.5 degrees, and 157.5 degrees, the frequency band in which the active S parameter was -10 dB or less was approximately the same.

[0223] This was also the case for the frequency characteristics of the active S2 parameter obtained at Port 2 of output port 102B as shown in Figure 32B, the frequency characteristics of the active S2 parameter obtained at Port 3 of output port 102B as shown in Figure 32C, and the frequency characteristics of the active S2 parameter obtained at Port 4 of output port 102B as shown in Figure 32D.

[0224] As described above, it has been confirmed that a one-dimensionally arranged antenna device having a parasitic strip is capable of beam scanning in an excellent state with reduced reflection, from angular regions with small beam scanning angles to angular regions with large beam scanning angles.

[0225] Note that the above description concerns a configuration in which parasitic strips 312P are provided on the −z and +z sides of a strip 312 extending in the z direction in response to vertically polarized radio waves. However, three parasitic strips 312P may be provided adjacent to the −y direction side of the three strips consisting of the strip 312 at the end of the −y direction and two parasitic strips 312P. These three parasitic strips 312P may have the same size as the other parasitic strips 312P in the yz plane view, be positioned in the z direction equal to the adjacent strip 312 and two parasitic strips 312P on the +y direction side, and be spaced apart in the y direction equal to the spacing between adjacent strips 312. Similarly, three parasitic strips 312P may be provided adjacent to the +y direction side of the three strips consisting of the strip 312 at the end of the +y direction and two parasitic strips 312P.

[0226] While exemplary antenna devices of the present disclosure have been described above, the present disclosure is not limited to the specifically disclosed embodiments, and various modifications and variations are possible without departing from the scope of the claims.

[0227] The following supplementary notes are further disclosed in relation to the above embodiments. (Supplementary Note 1) An antenna device including: a plurality of antenna elements capable of beam scanning; and a matching layer provided at a distance from the radiation surfaces of the plurality of antenna elements in the radiation direction of the plurality of antenna elements, wherein the matching layer has: a base made of a dielectric; and a plurality of strips provided on the base and made of a conductor, the plurality of strips being provided corresponding to the plurality of antenna elements, respectively, and the center of each antenna element overlapping with the corresponding strip when viewed from the radiation direction. (Supplementary Note 2) The antenna device according to Supplementary Note 1, wherein the plurality of strips extend along the polarization direction of radio waves radiated from the plurality of antenna elements. (Supplementary Note 3) The antenna device according to Supplementary Note 2, wherein the base has a plurality of periodic regions respectively corresponding to the plurality of antenna elements when viewed from the radiation direction, and where Pz is a length of the plurality of periodic regions in the polarization direction of the radio waves and Sz is a length of the strip in the polarization direction of the radio waves, a ratio Sz / Pz of the length Sz to the length Pz is not less than 0.3 and not more than 1. (Supplementary Note 4) The antenna device according to Supplementary Note 2, wherein the plurality of strips are arranged one-dimensionally, one strip at a time in the polarization direction of the radio waves radiated from the plurality of antenna elements, and a plurality of strips are arranged along a direction perpendicular to the polarization direction, and the base has a plurality of periodic regions respectively corresponding to the plurality of antenna elements when viewed from the radiation direction, and where Pz is a length of the plurality of periodic regions in the polarization direction of the radio waves and Sz is a length of the strip in the polarization direction of the radio waves, a ratio Sz / Pz of the length Sz to the length Pz is not less than 0.05 and not more than 1. (Supplementary Note 5) The antenna device according to Supplementary Note 4, further including a plurality of parasitic strips provided corresponding to the plurality of strips, two of which are provided so as to sandwich each of the plurality of strips in the extending direction of the plurality of strips. (Supplementary Note 6) The antenna device according to Supplementary Note 5, wherein a pitch between each of the strips and the two of the parasitic strips provided so as to sandwich each of the strips is not less than 0.05 λe and not more than 5 λe, where λe is the electrical length of a wavelength at an operating frequency of the antenna element.(Supplementary Note 7) The antenna device according to any one of Supplementary Notes 2 to 6, wherein the distance in the direction perpendicular to the polarization direction of the radio waves between the center of each antenna element and the center of the width of the corresponding strip in the direction perpendicular to the polarization direction of the radio waves is λe / 4 or less, where λe is the electrical length of a wavelength at the operating frequency of the plurality of antenna elements. (Supplementary Note 8) The antenna device according to any one of Supplementary Notes 1 to 7, wherein the distance in the radiation direction between the radiation surfaces of the plurality of antenna elements and the plurality of strips is Px, the thickness of the base in the radiation direction is dx, and the electrical length of a wavelength at the operating frequency of the plurality of antenna elements is λe, the distance Px is 0.1 λe or more and 0.5 λe or less, and the thickness dx is 10 μm or more and 10 mm or less. (Supplementary Note 9) The antenna device according to any one of Supplementary Notes 1 to 8, wherein the plurality of antenna elements are formed by input / output units of a Butler matrix feed circuit. (Supplementary Note 10) The antenna device according to Supplementary Note 9, wherein the plurality of antenna elements are configured as input / output units of a Butler matrix feed circuit realized by a waveguide, SIW, or post-wall waveguide. (Supplementary Note 11) The antenna device according to any one of Supplementary Notes 1 to 10, wherein beams radiated from the plurality of antenna elements have a reflection coefficient of -15 dB or less when the beam scanning angle is 60 degrees. (Supplementary Note 12) An antenna device comprising: a Butler matrix feed circuit realized with a waveguide and having a plurality of output sections; a bend structure that bends the propagation direction of electromagnetic waves output from the plurality of output sections by 90 degrees, the bend structure having a plurality of output ports that radiate the electromagnetic waves in a radiation direction bent by 90 degrees from the propagation direction; and matching layers provided at intervals between the plurality of output ports of the bend structure, wherein the matching layer has: a base made of a dielectric; and a plurality of strips provided on the base and made of a conductor, the plurality of strips being provided corresponding to the plurality of output ports, respectively, and the center of each output port overlaps with the corresponding strip when viewed from the radiation direction.

[0228] The disclosures of Japanese Patent Applications Nos. 2024-025135 and 2024-173812 are incorporated herein by reference in their entirety. All documents, patent applications, and technical standards mentioned herein are incorporated by reference into this specification to the same extent as if each individual document, patent application, and technical standard was specifically and individually indicated to be incorporated by reference.

[0229] 1, 3, 4, 5: Crisscross directional coupler 5a to 5f: Phase shifter 41: Fourth waveguide 45, 46: Recess 50: Space 101: Butler matrix feed circuit 102A: Input port 1 102B: Output port 102B1: Center 111: First waveguide 112: Second waveguide 113: Third waveguide 130: Bend structure 140: Output section 141: Output port 150: Beam 300, 300M: Antenna device 310: Matching layer 311: Substrate 312: Strip

Claims

1. An antenna device comprising: a plurality of antenna elements capable of beam scanning; and a matching layer provided at a distance from the radiation surfaces of the plurality of antenna elements in the radiation direction of the plurality of antenna elements, wherein the matching layer has a base made of a dielectric material; and a plurality of strips provided on the base and made of a conductor, the plurality of strips being provided corresponding to the plurality of antenna elements, respectively, and the center of each antenna element overlapping with the corresponding strip when viewed from the radiation direction.

2. The antenna device according to claim 1, wherein the plurality of strips extend along the polarization direction of radio waves radiated from the plurality of antenna elements.

3. The antenna device according to claim 2, wherein the base has a plurality of periodic regions respectively corresponding to the plurality of antenna elements when viewed from the radiation direction, and the ratio Sz / Pz of the length Sz to the length Pz is 0.3 or more and 1 or less, where Pz is the length of the plurality of periodic regions in the polarization direction of the radio waves, and Sz is the length of the strip in the polarization direction of the radio waves.

4. The antenna device according to claim 2, wherein the plurality of strips are arranged one-dimensionally in the direction of polarization of radio waves radiated from the plurality of antenna elements, and the plurality of strips are arranged along a direction perpendicular to the direction of polarization, and the base has a plurality of periodic regions corresponding to the plurality of antenna elements when viewed from the radiation direction, and the ratio Sz / Pz of the length Sz to the length Pz is 0.05 or more and 1 or less, where Pz is the length of the plurality of periodic regions in the direction of polarization of the radio waves and Sz is the length of the strip in the direction of polarization of the radio waves.

5. The antenna device according to claim 4, further comprising a plurality of parasitic strips provided corresponding to the plurality of strips, with two parasitic strips provided on either side of each strip in the extension direction of the plurality of strips.

6. An antenna device as described in claim 5, wherein the pitch between each strip and the two parasitic strips arranged to sandwich the strip is 0.05 λe or more and 5 λe or less, where λe is the electrical length of the wavelength at the operating frequency of the antenna element.

7. The antenna device according to claim 2, wherein the distance in the direction perpendicular to the polarization direction of the radio waves between the center of each antenna element and the center of the width of the corresponding strip in the direction perpendicular to the polarization direction of the radio waves is λe / 4 or less, where λe is the electrical length of the wavelength at the operating frequency of the plurality of antenna elements.

8. The antenna device according to claim 1, wherein the distance in the radiation direction between the radiation surfaces of the plurality of antenna elements and the plurality of strips is Px, the thickness in the radiation direction of the base is dx, and the electrical length of the wavelength at the operating frequency of the plurality of antenna elements is λe, the distance Px is not less than 0.1 λe and not more than 0.5 λe, and the thickness dx is not less than 10 μm and not more than 10 mm.

9. The antenna device according to any one of claims 1 to 5, wherein the plurality of antenna elements are configured as input / output sections of a Butler matrix feed circuit.

10. The antenna device of claim 9, wherein the plurality of antenna elements are configured at the inputs and outputs of a Butler matrix feed circuit implemented in waveguide, SIW, or post-wall waveguide.

11. The antenna device according to claim 1, wherein the beams radiated from said plurality of antenna elements have a reflection coefficient of -15 dB or less when the beam scanning angle is 60 degrees.

12. An antenna device comprising: a Butler matrix feed circuit realized with waveguides and having a plurality of output sections; a bend structure that bends the propagation direction of electromagnetic waves output from the plurality of output sections by 90 degrees, the bend structure having a plurality of output ports that radiate electromagnetic waves in a radiation direction bent by 90 degrees from the propagation direction; and matching layers provided at intervals between the plurality of output ports of the bend structure, wherein the matching layer has a base made of a dielectric material and a plurality of strips provided on the base and made of a conductor, the plurality of strips being provided corresponding to the plurality of output ports, respectively, and the center of each output port overlaps with the corresponding strip when viewed from the radiation direction.

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