Waveguide slot array antenna and method for manufacturing waveguide slot array antenna

Abstract

The ridge portion satisfies the conditions for manufacturing by diffusion bonding, and a high-gain waveguide slot array antenna with a beamforming function is provided. [Solution] A waveguide slot array antenna in which multiple waveguide slot subarrays are arranged in parallel, each of which is a waveguide with a rectangular cross-section surrounded by two opposing wide walls and two opposing narrow walls that connect the two wide walls and are narrower than the wide walls, and which has multiple slots provided in one of the wide walls, a ridge portion provided in the other wide wall, and a first matching element on the other wide wall, of the same thickness as the ridge portion, connecting the ridge portion and the narrow walls.

Description

Technical Field

[0001] The present invention relates to a waveguide slot array antenna and a method for manufacturing a waveguide slot array antenna.

Background Art

[0002] Non-Patent Document 1 describes that in a two-layer slot waveguide antenna manufactured by laminating thin metal plates formed by etching and diffusion bonding, the number of metal plates to be laminated is reduced by supplying alternating phases.

Prior Art Document

Non-Patent Document

[0003]

Non-Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] To realize long-distance communication in the millimeter wave band, a high gain of the antenna is required. When designing an antenna on a printed circuit board, it is easy to integrate with a beamforming module configured on the printed circuit board, but it is not suitable for achieving high gain due to the loss of the transmission line. A waveguide with low loss is suitable for achieving high gain. From the transmission conditions of the waveguide and the conditions of beamforming, a ridge waveguide is suitable for the waveguide. When manufacturing a ridge waveguide by diffusion bonding, it is difficult for the ridge portion of the ridge waveguide to satisfy the manufacturing conditions by diffusion bonding. An object of the present invention is to provide a high-gain waveguide slot array antenna having a beamforming function while satisfying the conditions for manufacturing a ridge portion by diffusion bonding.

Means for Solving the Problems

[0005] The invention according to claim 1 is a waveguide slot array antenna in which a plurality of waveguide slot sub-arrays are arranged in parallel. The waveguide slot sub-array is a waveguide having a quadrangular cross-section surrounded by two wide walls facing each other and two narrow walls facing each other that connect the two wide walls and are narrower than the wide walls. It is a waveguide slot array antenna comprising a plurality of slots provided in one of the wide walls, a ridge portion provided in the other wide wall, and a first matching element provided on the other wide wall having the same thickness as the ridge portion and connecting the ridge portion and the narrow wall. The invention according to claim 2 is the waveguide slot array antenna according to claim 1, further comprising a second matching element provided on the narrow wall and connecting between the two wide walls or between the first matching element and the wide wall facing the wide wall on which the first matching element is provided. The invention according to claim 3 is the waveguide slot array antenna according to claim 1, further comprising a converter provided on the wide wall on which the ridge portion is provided, the converter having a tapered portion connected to the ridge portion and gradually widening in width from the ridge portion, and two narrow walls having an interval gradually widening from the interval between the narrow walls to which the tapered portion is connected. The invention according to claim 4 is the waveguide slot array antenna according to claim 1 or 2, wherein the plurality of waveguide slot sub-arrays in the waveguide slot array antenna are serially fed to the slots from an input / output port provided at an end, and are arranged in parallel such that the input / output ports are staggered in the longitudinal direction of the waveguide slot sub-array in the direction of adjacent waveguide slot sub-arrays. The invention according to claim 5 is the waveguide slot array antenna according to claim 4, wherein a wiring board provided with a beam forming circuit for forming the beam of the waveguide slot array antenna is provided on the side opposite to the side where the slots are provided, and a signal for controlling beam forming is supplied to the input / output port. The invention according to claim 6 includes a step of creating a plurality of thin plate members parallel to the broad wall, which become the waveguide slot array antenna according to claim 1 by overlapping, and a step of overlapping the plurality of thin plate members and heating them at a temperature below the melting point of the thin plate members while applying pressure to diffusion-bond the plurality of thin plate members, which is a method for manufacturing a waveguide slot array antenna.

Advantages of the Invention

[0006] According to the invention described in claim 1, a high-gain waveguide slot array antenna with a beam forming function can be formed while satisfying the conditions for manufacturing the ridge portion by diffusion bonding. According to the invention described in claim 2, the adjustment of inductance becomes easier compared to the case where the second matching element is not provided. According to the invention described in claim 3, reflection is suppressed between the waveguide for power supply and the ridge waveguide, which is a waveguide slot sub-array, compared to the case where a converter is not used. According to the invention described in claim 4, the change in the beam direction radiated by the waveguide slot array antenna is suppressed compared to the case where they are not staggered. According to the invention described in claim 5, the waveguide slot array antenna can be configured in a flat plate shape compared to the case where the beam forming circuit is not provided on the wiring board. According to the invention described in claim 6, a waveguide slot array antenna using a ridge waveguide can be manufactured by diffusion bonding.

Brief Description of the Drawings

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Embodiments for Carrying Out the Invention

[0008] Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings. Note that members having the same function may be denoted by the same reference numerals. Also, some configurations may be given reference numerals, and similar configurations may not be given reference numerals.

[0009] When the communication target such as mobile communication moves, the antenna is required to have a beamforming function. Such an antenna is required to be able to change the direction of the beam over a wide range in a direction horizontal to the ground surface (horizontal direction).

[0010] A circuit (beamforming module) for controlling an RF signal for performing beamforming is provided on a wiring board, a so-called printed circuit board. That is, the beamforming module has a flat plate shape. In order to connect and integrate the antenna and the beamforming module without using a cable (cableless), it is preferable that the antenna also has a flat plate shape. When the antenna is provided on a wiring board such as a printed circuit board, it is easy to integrate with the beamforming module, but it is difficult to obtain high gain due to the loss of the transmission line. Since the waveguide has low loss, the antenna can obtain high gain. Therefore, a waveguide provided with a plurality of slots is used as a subarray, and a plurality of subarrays are arranged in parallel to realize a flat plate-shaped antenna. This antenna is referred to as a waveguide slot array antenna, and the subarray is referred to as a waveguide slot subarray.

[0011] (First Embodiment) FIG. 1 is a diagram for explaining an example of a waveguide slot array antenna 1 to which the first embodiment is applied. FIG. 1(a) is a plan view, and FIG. 1(b) is a side view. In FIG. 1(a), the right direction of the paper surface is the x direction, the upward direction of the paper surface is the y direction, and the surface direction of the paper surface is the z direction. In FIG. 2(b), the left direction of the paper surface is the z direction, the upward direction of the paper surface is the y direction, and the surface direction of the paper surface is the x direction. Hereinafter, the directions are as shown in the figure, and the description thereof will be omitted. Note that the +z direction of the waveguide slot array antenna 1 may be referred to as the front side, and the -z direction may be referred to as the back side.

[0012] The waveguide slot array antenna 1 includes a waveguide slot array module 10. Note that the waveguide slot array antenna 1 may include a radiation aperture module 20. Further, the waveguide slot array antenna 1 may include a beamforming module 30. As shown in FIG. 1(b), the radiation aperture module 20 is provided on one side (here, the +z direction side) of the waveguide slot array module 10. The beamforming module 30 is provided on the other side of the waveguide slot array module 10 (here, the -z direction side, which is the side opposite to the side where the slot 121 to be described later is provided). The waveguide slot array module 10, the radiation aperture module 20, and the beamforming module 30 are all configured in a flat plate shape. By overlapping the waveguide slot array module 10, the radiation aperture module 20, and the beamforming module 30 and fixing them with a fixing mechanism 50 such as a screw, the waveguide slot array antenna 1 including the radiation aperture module 20 and the beamforming module 30 is configured as a flat plate-shaped antenna as a whole.

[0013] The fixing mechanism 50 includes, for example, a hole and a bolt and nut (notation omitted). The hole is provided through the waveguide slot array module 10, the radiation aperture module 20, and the beamforming module 30. By passing a bolt through this hole and tightening it with a nut, the waveguide slot array module 10, the radiation aperture module 20, and the beamforming module 30 are integrated. Note that the fixing mechanism 50 may have other configurations. Hereinafter, the description of the fixing mechanism 50 will be omitted.

[0014] In the waveguide slot array antenna 1, the y-direction is the direction perpendicular to the ground surface (vertical direction), and the x-direction is the direction horizontal to the ground surface (horizontal direction). The waveguide slot array antenna 1 radiates radio waves toward the +z direction side. In the vertical direction, the waveguide slot array antenna 1 radiates beam-shaped radio waves in a fixed direction (without change) and with a small spread in the angle of the radiated radio waves. In the horizontal direction, the waveguide slot array antenna 1 changes the radiation direction over a wide range by the beamforming module 30. Here, it is described in terms of radiation, but generally, an antenna can perform both radio wave radiation and radio wave reception. Note that although the y-direction of the waveguide slot array antenna 1 is the direction perpendicular to the ground surface and the x-direction is the direction horizontal to the ground surface, the x-direction and the y-direction may face other directions.

[0015] As shown in FIG. 1(a), the waveguide slot array module 10 includes a plurality of waveguide slot sub-arrays 100. The waveguide slot sub-array 100 is a waveguide in which the ±y directions are radio wave transmission paths. The waveguide slot array module 10 is configured by arranging a plurality of waveguide slot sub-arrays 100 in the x-direction. When distinguishing the waveguide slot sub-arrays 100, as shown in FIG. 1(a), they are denoted as waveguide slot sub-arrays 100-1, 100-2,..., 100-8 in order in the x-direction. The waveguide slot array antenna 1 is composed of, for example, eight waveguide slot sub-arrays 100.

[0016] The waveguide slot sub-array 100 in the waveguide slot array antenna 1 includes eight radiating element parts 120. The waveguide slot array module 10 includes a slot 121 as an example of a radiating element for each radiating element part 120. The slot 121 has a longitudinal direction and a transverse direction. The longitudinal direction of the slot 121 faces the longitudinal direction of the waveguide slot sub-array 100. In the waveguide slot sub-array 100, the slots 121 arranged in the y direction are provided with an alternating shift in the ±x direction. Here, the waveguide slot sub-array 100 is virtually divided into each slot 121 in the longitudinal direction, and the portion including one divided slot 121 is denoted as the radiating element part 120.

[0017] The radiation aperture module 20 includes a radiation aperture 21. The radiation aperture 21 is provided corresponding to the slot 121 in the waveguide slot array module 10. The waveguide slot array antenna 1 radiates radio waves from the slot 121 through the radiation aperture 21. By using the radiation aperture 21, the reflection characteristics are broadened compared to the case where the radiation aperture 21 is not used. Note that the waveguide slot array antenna 1 may not include the radiation aperture module 20. The radiation aperture module 20 is formed by etching or the like on a flat plate of a metal such as copper (Cu), aluminum (Al), or stainless steel (SUS), and the radiation aperture 21 is provided.

[0018] FIG. 2 is a perspective view of the waveguide slot array antenna 1 viewed from the back side. The directions in FIG. 2 are as shown. The waveguide slot array module 10, the radiation aperture module 20, and the beamforming module 30 are overlapped and integrated. However, in FIG. 2, a state is shown in which the waveguide slot array module 10 and the radiation aperture module 20 are overlapped and the beamforming module 30 is removed and shifted.

[0019] The back surface of the waveguide slot array module 10 is the back side (sometimes also referred to as the outer side) of the wide wall 111 (see FIG. 3 described later) of the waveguide slot sub-array 100. The wide wall 111 is provided with an input / output port 190 for RF signals. The input / output port 190 is an opening provided at the end of the waveguide slot sub-array 100. The waveguide slot sub-array 100 is fed in series from the input / output port 190. Note that the input / output ports 190 of the waveguide slot sub-arrays 100 are arranged alternately in the ±y direction (see FIG. 1(a)) so as to avoid adjacent input / output ports 190 being adjacent to each other between adjacent waveguide slot sub-arrays 100, for example, between the waveguide slot sub-array 100-1 and the waveguide slot sub-array 100-2. That is, the waveguide slot sub-arrays 100 are arranged alternately in parallel so that their directions are opposite to each other. This is because when the input / output port 190 is a waveguide without a ridge portion 117 (see FIG. 3 described later), the waveguide forming the input / output port 190 will have a wider tube width. Therefore, by providing the input / output ports 190 alternately, mechanical interference between adjacent input / output ports 190 is avoided.

[0020] The beamforming module 30 includes a wiring board 31, a beamforming circuit 32, a microstrip line 33, and an RF signal input / output terminal 34.

[0021] The wiring board 31 is a so-called printed circuit board. The beamforming circuit 32 controls the phase and / or amplitude of the RF signal transmitted to the waveguide slot sub-array 100 of the waveguide slot array antenna 1 to cause beamforming in the waveguide slot array antenna 1. The RF signal from the beamforming circuit 32 propagates through the microstrip line 33 and is supplied to the RF signal input / output terminal 34.

[0022] The input / output terminal 34 of the RF signal is provided to face the input / output port 190 of the waveguide slot array module 10. The waveguide slot array module 10, the radiation aperture module 20, and the beamforming module 30 are integrated by being overlapped and fixed by the fixing mechanism 50. The beamforming module 30 and the waveguide slot array module 10 are connected without using wiring (cable).

[0023] Hereinafter, one waveguide slot sub-array 100 is taken out and described centering on the waveguide slot sub-array 100.

[0024] In order for radio waves to be transmitted in a waveguide with a rectangular cross-section, the tube width needs to be equal to or greater than half the wavelength (1 / 2λ) of the radio waves to be transmitted. On the other hand, the closer the distance between the waveguide slot sub-arrays 100 is to half the wavelength (1 / 2λ), the more beamforming in a wide angle range becomes possible. Note that λ is the wavelength of the radio waves. In the first embodiment, in order to enable beamforming in a wide angle range, a ridge portion is provided so that radio waves can be transmitted even when the tube width is made smaller than half the wavelength (1 / 2λ). By providing the ridge portion, the tube width effectively becomes wider.

[0025] Here, the waveguide slot array antenna 1 transmits and receives radio waves in the millimeter wave band, for example, the 60 GHz band. The wavelength λ of radio waves with a frequency of 60 GHz is approximately 5 mm. Then, the interval between the waveguide slot sub-arrays 100 is approximately 2.5 mm. The manufacturing of the waveguide slot array module 10 in which a plurality of waveguide slot sub-arrays 100 are arranged at such a fine interval of about 2.5 mm is difficult by methods such as cutting used for manufacturing waveguides with a wavelength λ longer than millimeter waves. Here, the waveguide slot sub-array 100 is manufactured by overlapping plate-like members (hereinafter referred to as thin plate members) and diffusion bonding. Diffusion bonding is a method of manufacturing by overlapping thin plate members of metal that have been pattern-processed by an etching method or the like, heating at a temperature below the melting point while applying pressure. Between the thin plate members, the thin plate members are joined by the mutual diffusion of metal atoms. Diffusion bonding suppresses the occurrence of sag, deformation, fillets, etc. that occur in welding, and the waveguide slot array module 10 can be manufactured with high precision.

[0026] Before explaining the waveguide slot sub-array 100 in the first embodiment, the conventional waveguide slot sub-array 100' will be explained. FIG. 3 is a diagram for explaining the problems that occur when manufacturing a conventional waveguide slot sub-array 100' provided with a ridge portion 117 by diffusion bonding. FIG. 3(a) is a cross-sectional view of the conventional waveguide slot sub-array 100', FIG. 3(b) is a perspective view of the conventional waveguide slot sub-array 100' seen with the wide wall 112 removed, and FIG. 3(c) is a perspective view of the thin plate member B of pattern B including the ridge portion 117 of the conventional waveguide slot sub-array 100'.

[0027] As shown in Fig. 3(a), a conventional waveguide slot subarray 100' having a ridge portion 117 is a waveguide with a rectangular cross-section in the x-z plane. The waveguide slot subarray 100' includes wide walls 111, 112, narrow walls 113, 114, end walls 115, 116, and a ridge portion 117. The wide walls 111, 112 are planes parallel to the x-y plane and face each other. The narrow walls 113, 114 are planes parallel to the z-y plane, face each other, and connect between the wide walls 111, 112. The widths of the wide walls 111, 112 are wider than the widths of the narrow walls 113, 114. A slot 121 through which radio waves are radiated is provided in the wide wall 112. The ridge portion 117 is provided so as to extend in the y direction on the wide wall 111 as shown in Fig. 3(b). The end walls 115, 116 shown in Fig. 3(b) will be described later.

[0028] In Fig. 3(a), the boundaries of the thin plate members to be overlapped when manufacturing the conventional waveguide slot subarray 100' by diffusion bonding are shown by broken lines. The waveguide slot subarray 100' is manufactured by overlapping a thin plate member A of pattern A that constitutes the wide wall 111 from the back side, a thin plate member B of pattern B that constitutes the ridge portion 117 and the narrow walls 113, 114, a thin plate member C of pattern C that constitutes the narrow walls 113, 114, and a thin plate member D of pattern D that constitutes the wide wall 112 provided with the slot 121. Note that, to avoid complexity, the reference signs of the thin plate members and the patterns are made the same. In Fig. 3(a), the waveguide slot subarray 100' is manufactured using one thin plate member A, three thin plate members B, seven thin plate members C, and one thin plate member D. Each pattern of the thin plate members A, B, C, D is processed by etching. For example, a production plate for screen printing is created, and a metal plate is etched based on the resist formed through the production plate. Instead of using a production plate for screen printing, a production plate for exposure may be created for each pattern of the thin plate members A, B, C, D. Note that the fewer the number of production plates, the lower the initial cost.

[0029] In diffusion bonding, as shown by the arrows in Fig. 3(a), after stacking thin plate members A, B, C, and D in predetermined numbers, pressure is applied from above (+z direction side) and heating is performed at a temperature below the melting point, so that metal elements diffuse into each other between the thin plate members and the thin plate members are joined together.

[0030] As shown in Fig. 3(b), the waveguide slot subarray 100' seen with the wide wall 112 removed includes an input / output port 190 where the wide wall 111 is removed and an opening is formed at the -y direction end. End walls 115 connecting between the narrow walls 113 and 114 are provided at the -y direction end, and end walls 116 connecting between the narrow walls 113 and 114 are provided at the +y direction end. That is, the waveguide slot subarray 100' is a space surrounded by the wide walls 111 and 112, the narrow walls 113 and 114, and the end walls 115 and 116, and radio waves are input from the input / output port 190 and radiated from the slots 121.

[0031] The thin plate member B (denoted as pattern B in Fig. 3(c)) formed in the pattern B shown in Fig. 3(c) includes portions that become the narrow walls 113 and 114, the end walls 115 and 116, and the ridge portion 117. In the pattern B (thin plate member B), the portions that become the narrow walls 113 and 114, the end walls 115 and 116, and the ridge portion 117 are denoted as the narrow walls 113 and 114, the end walls 115 and 116, and the ridge portion 117.

[0032] Here, it will be explained that it is difficult to manufacture the waveguide slot subarray 100' having the ridge portion 117 by diffusion bonding. As described above, in diffusion bonding, heating is performed while applying pressure. In Fig. 3(a), the ridge portion 117 indicated by α is not subjected to pressure application. In the case of the 60 GHz band, the width W of the ridge portion 117 R is, for example, 0.6 mm, and the length L of the ridge portion 117 RFor example, it is 36 mm. The ridge portion 117 is in the form of a thin line. One end portion indicated by β (+y direction end portion) is connected to the end wall 116 of the ridge portion 117 and is less likely to be displaced. On the other hand, the other end portion of the ridge portion 117 indicated by γ (-y direction end portion) is not connected to the end wall 115 or the like, so it is likely to be displaced. Therefore, the ridge portion 117 of the conventional waveguide slot subarray 100' is not under insufficient pressure and is likely to be displaced. For this reason, it is difficult to manufacture the waveguide slot subarray 100' with high precision.

[0033] The plurality of waveguide slot subarrays 100' of the waveguide slot array module 10 may be manufactured integrally. That is, in adjacent waveguide slot subarrays 100', the narrow wall 114 of the waveguide slot subarray 100' on the left side (-x direction side) is configured to also serve as the narrow wall 113 of the waveguide slot subarray 100' on the right side (+x direction side). The waveguide slot array module 10 is configured in a flat plate shape. The same applies to the waveguide slot subarray 100 in the first embodiment described later.

[0034] There are two ways to excite the waveguide slot subarray: standing wave excitation and traveling wave excitation. In standing wave excitation, matching is achieved by adjusting the admittance characteristics of the radiation element portion 120 including the slot 121. In standing wave excitation, matching elements such as stubs and irises are not used for matching. On the other hand, in traveling wave excitation, matching is achieved by providing matching elements such as stubs and irises for each radiation element portion 120 including the slot 121.

[0035] In the waveguide slot subarray 100 in the first embodiment, traveling wave excitation is used. And the waveguide slot subarray 100 in the first embodiment suppresses insufficient pressure and displacement of the ridge portion 117 by using matching elements. Hereinafter, the waveguide slot subarray 100 in the first embodiment will be described in comparison with the conventional waveguide slot subarray 100'. Note that the same parts will be denoted by the same reference numerals and the description thereof will be omitted.

[0036] FIG. 4 is a diagram for explaining the configuration of the waveguide slot sub-array 100 in the first embodiment. FIG. 4(a) is a perspective view of the appearance of the waveguide slot sub-array 100 and the conventional waveguide slot sub-array 100' in the first embodiment. FIG. 4(b) is a perspective view of the conventional waveguide slot sub-array 100' with the broad wall 112 shown by a dashed line. FIG. 4(c) is a perspective view of the waveguide slot sub-array 100 in the first embodiment with the broad wall 112 shown by a dashed line. In FIGS. 4(a), (b), and (c), three radiating element portions 120 are shown. The directions in FIGS. 4(a), (b), and (c) are as shown.

[0037] As shown in FIG. 4(a), the appearance of the waveguide slot sub-array 100 in the first embodiment and the conventional waveguide slot sub-array 100' is the same. Therefore, they are denoted as the waveguide slot sub-array 100 / 100'. In FIG. 4(a), slots 121 are provided in the broad wall 112. Note that the broad wall 112 where the slots 121 are provided may be called a slot plate.

[0038] As shown in Fig. 4(b), in the conventional waveguide slot subarray 100', a matching element 131 called an iris is provided for each radiating element section 120. The matching element 131 is a member provided on the narrow wall 113 or 114 so as to connect the wide walls 111 and 112. The matching element 131 reduces the cross-sectional area of the waveguide from the narrow wall 113 side or the narrow wall 114 side and adjusts the inductance. Note that the amount (protrusion amount) by which the matching element 131 protrudes from the narrow walls 113 and 114 to the central portion of the waveguide is set according to the required inductance. Also, when the required inductance is small, the matching element 131 may not be provided for the radiating element section 120. In Fig. 4(b), the cross-sectional shape of the tip portion where the matching element 131 protrudes to the central portion of the waveguide is rounded, but it does not have to be rounded. The matching element 131 in the conventional waveguide slot subarray 100' is provided on the narrow walls 113 and 114 and is not connected to the ridge portion 117. In the conventional waveguide slot subarray 100', even if the matching element 131 is provided, the insufficient pressurization and displacement of the ridge portion 117 described with reference to Figs. 3(a) and (c) are not suppressed.

[0039] The waveguide slot subarray 100 in the first embodiment shown in Fig. 4(c) further includes a first matching element 132 and a second matching element 133 in addition to the conventional waveguide slot subarray 100'. The first matching element 132 is a member provided on the wide wall 111 and connecting the ridge portion 117 and the narrow wall 113. The thickness of the first matching element 132 is set to be the same as that of the ridge portion 117. In Fig. 4(c), two first matching elements 132 are provided on both sides of the ridge portion 117 so as to sandwich the ridge portion 117. Also, the two first matching elements 132 are provided for all of the three radiating element sections 120 shown in Fig. 4(c). The first matching element 132 reduces the cross-sectional area of the waveguide from the wide wall 111 side and adjusts the inductance. The waveguide slot subarray 100 is a ridge waveguide having a rectangular cross-section in the x-z plane and is made of a metal such as copper (Cu), aluminum (Al), or stainless steel (SUS).

[0040] The second matching element 133 is provided on the narrow wall 113 or the narrow wall 114 in the waveguide so as to connect the first matching element 132 and the wide wall 112. In Fig. 4(c), in each radiating element section 120, one second matching element 133 is provided on the narrow wall 113 or the narrow wall 114 on the side far from the slot 121. The second matching element 133 reduces the cross-sectional area of the waveguide from the narrow wall 113 side or the narrow wall 114 side and adjusts the inductance.

[0041] In the radiating element section 120, when the required inductance is small, the first matching element 132 may be provided only on one side (one-sided) with respect to the ridge portion 117. In this case, the second matching element 133 does not necessarily need to be provided so as to be connected to the first matching element 132. That is, the second matching element 133 may be provided so as to connect the wide wall 111 and the wide wall 112, similarly to the matching element 131 of the conventional waveguide slot subarray 100'. In the radiating element section 120, when the required inductance is even smaller, the first matching element 132 does not necessarily need to be provided.

[0042] The amount by which the second matching element 133 protrudes from the narrow walls 113 and 114 toward the central portion of the waveguide (protrusion amount) may be set according to the required inductance, similarly to the matching element 131. When the required inductance is small, the second matching element 133 does not necessarily need to be provided.

[0043] Fig. 5 is a diagram for explaining a method of manufacturing the waveguide slot subarray 100 in the first embodiment including the ridge portion 117 by diffusion bonding. Fig. 5(a) is a diagram for explaining patterns A, B, C, and D of the thin plate member used for manufacturing the waveguide slot subarray 100, and Fig. 5(b) is a diagram for explaining a state in which the thin plate members are overlapped and diffusion bonded. The directions in Figs. 5(a) and 5(b) are as shown.

[0044] In the waveguide slot sub-array 100 according to the first embodiment, the ridge portion 117 is connected to the narrow wall 113 or the narrow wall 114 by the first matching element 132. Therefore, as shown in Fig. 5(a), in the waveguide slot sub-array 100 according to the first embodiment, unlike the thin plate member B shown in Fig. 3(c), in the thin plate member B including the ridge portion 117, the ridge portion 117 is connected to the narrow wall 113 or the narrow wall 114 by the first matching element 132. Since the thickness of the first matching element 132 is set to be the same as the thickness of the ridge portion 117, in all the thin plate members B, the ridge portion 117 indicated by α is connected to the narrow wall 113 or the narrow wall 114 by the first matching element 132. As shown in Fig. 5(b), while the narrow walls 113 and 114 are pressurized, the ridge portion 117 is pressurized via the first matching element 132. The ridge portion 117 indicated by α has a fixed distance from the narrow wall 113 and / or the narrow wall 114 by the first matching element 132, and displacement of the ridge portion 117 is suppressed.

[0045] Fig. 6 is a perspective view of an example of the waveguide slot sub-array 100 according to the first embodiment. The directions in Fig. 6 are as shown. As shown in Fig. 6, the waveguide slot sub-array 100 is configured by combining the first matching element 132 and the second matching element 133. As shown in Fig. 6, in the waveguide slot sub-array 100, the first matching element 132 may not be provided in all the radiation element portions 120. Similarly, the second matching element 133 may not be provided in all the radiation element portions 120 of the waveguide slot sub-array 100. The amount of protrusion of the second matching element 133 from the narrow wall 113 or the narrow wall 114 may be different between the radiation element portions 120. Also, there may be a radiation element portion 120 that does not include the second matching element 133.

[0046] Next, the radiation performance of the waveguide slot sub-array 100 when the first matching element 132 and the second matching element 133 are provided will be described. FIG. 7 is a diagram for explaining the radiation performance when the first matching element 132 and the second matching element 133 are provided. FIG. 7(a) is a perspective view of the appearance of one radiation element section 120, FIG. 7(b) is a perspective view of the radiation element section 120 (Model A) in the conventional waveguide slot sub-array 100' using the matching element 131, FIG. 7(c) is a perspective view of the radiation element section 120 (Model B) using one first matching element 132 and one second matching element 133 in the waveguide slot sub-array 100 of the first embodiment, FIG. 7(d) is a perspective view of another radiation element section 120 (Model C) using one first matching element 132 and one second matching element 133 in the waveguide slot sub-array 100 of the first embodiment, and FIG. 7(e) shows the reflection characteristics of each model. FIGS. 7(b), (c), and (d) are diagrams in which the radiation aperture module 20 and the broad wall 112 (see FIG. 4(a)) are separated by the dashed line shown in FIG. 7(a). In FIGS. 7(b), (c), and (d), the slot 121 is indicated by a dashed line. The directions in FIGS. 7(a), (b), (c), and (d) are as shown.

[0047] The appearance of the waveguide slot sub-array 100 in the first embodiment shown in FIG. 7(a) is the same as that of the conventional waveguide slot sub-array 100'. Therefore, it is denoted as the waveguide slot sub-array 100 / 100'. A radiation aperture module 20 having a radiation aperture 21 is provided on the waveguide slot sub-array 100 / 100'. In one radiation element section 120, one end (-y direction side end) is defined as Port1 and the other end (+y direction side end) is defined as Port2. The reflection characteristic (S11 in the S parameter) with respect to Port1 was obtained by simulation.

[0048] FIG. 7(b) shows the radiation element section 120 (Model A) in the conventional waveguide slot sub-array 100', in which a matching element 131 called a so-called iris is provided on the narrow wall 113.

[0049] FIG. 7(c) shows the radiation element section 120 (Model B) in the waveguide slot sub-array 100 of the first embodiment, where a first matching element 132 is provided on the side of the narrow wall 114 on the wide wall 112, and a second matching element 133 is provided on the narrow wall 113.

[0050] FIG. 7(d) shows another radiation element section 120 (Model C) in the waveguide slot sub-array 100 of the first embodiment, where a first matching element 132 is provided on the side of the narrow wall 113 on the wide wall 112, and a second matching element 133 is provided on the narrow wall 113. The second matching element 133 is provided so as to overlap the first matching element 132.

[0051] As shown in FIG. 7(e), the reflection characteristics of the waveguide slot sub-array 100 of the first embodiment in Models B and C are equal to or better than those of the conventional waveguide slot sub-array 100' in Model A. That is, by providing the first matching element 132 so as to connect to the ridge portion 117, it is possible to avoid insufficient pressure on the ridge portion 117 and suppress displacement during diffusion bonding without affecting the radiation characteristics.

[0052] Next, the converter 140 between the waveguide slot sub-array 100 and the input / output port 190 in the first embodiment will be described. The converter 140 is a member that converts the transmission mode between the waveguide slot sub-array 100, which is a waveguide with a ridge portion (ridge waveguide), and the input / output port 190, which is a waveguide without a ridge portion (waveguide).

[0053] FIG. 8 is a diagram for explaining the converter 140 in the first embodiment. FIG. 8(a) is a perspective view of the waveguide slot sub-array 100 with the wide wall 112 removed, and FIG. 8(b) is a perspective view of Pattern B (thin plate member B) including the converter 140 portion. The directions in FIGS. 8(a) and 8(b) are as shown.

[0054] As shown in FIG. 8(a), the converter 140 includes a tapered portion 141 and narrow walls 143 and 144. The tapered portion 141 is provided connected to the ridge portion 117 between the ridge portion 117 and the input / output port 190, and its width gradually widens in a tapered shape from the ridge portion 117 and contacts the narrow walls 143 and 144 in front of the input / output port 190. The narrow wall 143 consists of a narrow wall 143a and a narrow wall 143b, and the narrow wall 144 consists of a narrow wall 144a and a narrow wall 144b. The narrow wall 143a and the narrow wall 144a are each connected to the narrow wall 113 and the narrow wall 114. The distance between the narrow wall 143a and the narrow wall 144a gradually widens from the distance between the narrow wall 113 and the narrow wall 114. The distance W2 between the narrow wall 143b and the narrow wall 144b, which are each connected to the narrow wall 143a and the narrow wall 144a, is constant. The distance W2 is wider than the distance W1 between the narrow wall 113 and the narrow wall 114 that sandwich the ridge portion 117. This is because it is necessary to make the waveguide width (distance W2) of the waveguide without the ridge portion 117 wider than the waveguide width (distance W1) of the waveguide with the ridge portion 117. Note that the narrow walls 143b and 144b are connected to the end wall 116. If the width of the tapered portion 141 and the distance between the narrow wall 143a and the narrow wall 144a are changed in a curved shape, reflection is easily suppressed.

[0055] The thickness of the tapered portion 141 is set to be the same as the thickness of the ridge portion 117. Thereby, in the thin plate member B including the tapered portion 141, the end portion of the ridge portion 117 indicated by α is connected to the narrow wall 143 continuous with the narrow wall 113 and the narrow wall 144 continuous with the narrow wall 114 by the tapered portion 141, so that displacement in diffusion bonding is suppressed.

[0056] FIG. 9 is a diagram for explaining the conversion characteristics of the converter 140. FIG. 9(a) is a perspective view of the converter 140, FIG. 9(b) is a perspective view of the converter 140 cut along the broken line in FIG. 9(a), and FIG. 9(c) is the reflection characteristic representing the conversion characteristics of the converter 140. The directions in FIGS. 9(a) and 9(b) are as shown. In FIG. 9(c), the horizontal axis is the frequency [GHz], and the vertical axis is the S11 [dB] indicating the reflection characteristic.

[0057] As shown in Fig. 9(a), in the converter 140, no slot is provided in the wide wall 112. As can be seen from Fig. 9(b), the side where the ridge portion 117 of the converter 140 is provided (ridge waveguide side) is defined as Port1, and the side connected to the narrow walls 143 and 144 of the taper portion 141 (waveguide side) is defined as Port2. Here, the reflection characteristic (S11 in the S parameter) with respect to Port1 was obtained by simulation.

[0058] As shown in Fig. 9(c), S11 indicating the reflection characteristic is extremely small, being -30 dB or less in the frequency range from 56 GHz to 64 GHz. That is, by passing through the converter 140, radio waves can be transmitted from the ridge waveguide side to the waveguide side with a small loss.

[0059] Fig. 10 is a diagram showing the radiation characteristics when the main beam of the waveguide slot array antenna 1 of the first embodiment is directed in the front direction. Fig. 10(a) shows the radiation pattern, and Fig. 10(b) shows the reflection characteristic. The directions in Fig. 10(a) are as shown. In Fig. 10(b), the horizontal axis represents the frequency [GHz], and the vertical axis represents S11 [dB] indicating the reflection characteristic.

[0060] As shown in Fig. 10(a), Port1 to Port8 were set in the waveguide slot array antenna 1. The RF signal exciting the waveguide slot sub-array 100 was supplied from the waveguide through the above-described converter 140. With the same excitation conditions for each Port, the radiation characteristics of the waveguide slot array antenna 1 were obtained by simulation. The excitation conditions in each waveguide slot sub-array 100 were the same. That is, the phase condition of the RF signal supplied to each waveguide slot sub-array 100 was set so that the main beam would face in the front direction (z direction), which is perpendicular to the waveguide slot array antenna 1. Therefore, in the radiation pattern, the main beam is directed in the front (z direction), which is perpendicular to the waveguide slot array antenna 1.

[0061] As shown in Fig. 10(b), S11 indicating the reflection characteristics at Ports 1, 4, and 8 is almost the same at frequencies from 56 GHz to 64 GHz and has little frequency dependence.

[0062] Fig. 11 is a diagram for explaining the directivity when the main beam of the waveguide slot array antenna 1 in the first embodiment is directed in the front direction. Fig. 11(a) shows the vertical plane directivity, and Fig. 11(b) shows the horizontal plane directivity. In the graphs of Fig. 11(a) and (b), the horizontal axis represents the angle [°], and the vertical axis represents the relative gain [dB]. Note that the vertical plane is the y - z plane shown in Fig. 10(a), and the horizontal plane is the z - x plane shown in Fig. 10(a). The +z direction is 0°. Also, the main beam direction [°], half - value width [°], and directivity gain [dB] are shown in a table.

[0063] The vertical plane directivity and horizontal plane directivity shown in Fig. 11(a) and (b) are almost the same at 58 GHz, 60 GHz, and 62 GHz and have little frequency dependence. Also, the main beam direction is 0°, the half - value width is approximately 8° in the vertical plane directivity and approximately 10° in the horizontal plane directivity, and the difference with frequency is small. That is, the waveguide slot array antenna 1 can be used in these frequency ranges.

[0064] Fig. 12 is a diagram showing the radiation characteristics when the main beam of the waveguide slot array antenna 1 of the first embodiment is directed from the front direction to the - 26° direction in the horizontal plane by phase control of each waveguide slot sub - array 100. Fig. 12(a) shows the radiation pattern at 58 GHz, Fig. 12(b) shows the radiation pattern at 60 GHz, Fig. 12(c) shows the radiation pattern at 62 GHz, and Fig. 12(d) shows the horizontal plane directivity. The directions in Fig. 12(a), (b), and (c) are as shown. In the graph of Fig. 12(d), the horizontal axis represents the angle [°], and the vertical axis represents the relative gain [dB].

[0065] The phase conditions of the RF signals supplied to each waveguide slot sub - array 100 are set (phase - controlled) so that the main beam of the waveguide slot array antenna 1 is directed to the - 26° direction in the horizontal plane. As shown in Fig. 12(a), in the directions of frequencies 58 GHz, 60 GHz, and 62 GHz, the direction of the main beam is approximately -26°, and the half-value width is approximately 11°. There is little difference from the radiation characteristics when the main beam is directed in the front direction shown in Fig. 11. That is, the waveguide slot array antenna 1 is an antenna capable of beamforming in the 60 GHz band. And the waveguide slot array antenna 1 to which the first embodiment is applied can be manufactured with high precision by diffusion bonding.

[0066] Next, a manufacturing method of the waveguide slot array antenna 1 will be described. Note that the waveguide slot array antenna 1 is configured by overlapping a waveguide slot array module 10, a radiation aperture module 20, and a beamforming module 30. As described above, these are fixed by a fixing mechanism 50. Therefore, it suffices to describe the manufacturing method of the waveguide slot array module 10 for the manufacturing method of the waveguide slot array antenna 1.

[0067] As shown in Fig. 5(a), after designing the waveguide slot sub-array 100, it is cut along a plane parallel to the broad wall 111 to create thin plate members corresponding to different patterns (patterns A, B, C, D in Fig. 5) (a step of manufacturing a plurality of thin plate members). Then, as shown in Fig. 5(b), these thin plate members of the patterns are overlapped in the required number, pressurized, and heated at a temperature below the melting point of the thin plate members for diffusion bonding (a step of diffusion bonding). Thereby, the waveguide slot array module 10 is manufactured.

[0068] (Second Embodiment) In the waveguide slot array antenna 1 according to the first embodiment, the waveguide slot sub-array 100 was fed in series from the end of the array. In this case, the beam direction of the waveguide slot sub-array 100 changes when the frequency is changed. However, in the waveguide slot array antenna 1, the adjacent waveguide slot sub-arrays 100 were arranged alternately in parallel such that the input / output ports 190 to be fed were at the ends in the ±y directions. As a result, the change in the beam direction was canceled out in the entire waveguide slot array antenna 1. However, grating lobes were likely to occur when beamforming was performed.

[0069] The grating lobe will be described. In the waveguide slot array antenna 1 according to the first embodiment, when the phase condition is set such that the main beam is in the -26° direction, beams Ga and Gb separated in the ±y directions are generated. The beams Ga and Gb are grating lobes. The grating lobes appear as two separated in the y direction. When distinguishing the beams Ga and Gb by frequency, the numerical value of the frequency is appended for notation. When the design frequency is 60 GHz, the beams Ga 58 and Gb 58 at 58 GHz in Fig. 12(a), and the beams Ga 62 and Gb 62 at 62 GHz in Fig. 12(c) are larger than the beams Ga 60 and Gb 60 at 60 GHz shown in Fig. 12(b). Thus, when beamforming is performed, grating lobes are likely to occur at frequencies other than the design frequency (here, 60 GHz).

[0070] To suppress the generation of grating lobes, it is advisable to feed power from the center so as to bisect the waveguide slot subarray 100. When attempting to equally divide the number of radiating element sections 120 in the waveguide slot subarray 100, the position where the branch circuit for branching the power feed in two directions (the position in the y direction in Fig. 1(a)) is the same between adjacent waveguide slot subarrays 100. When the branch circuit is composed of waveguides, it becomes necessary to make the waveguide width of the waveguides constituting the branch circuit equal to or less than the waveguide width of the waveguide slot subarray 100 which is a ridge waveguide. If the waveguide width of the waveguides constituting the branch circuit exceeds the waveguide width of the waveguide slot subarray 100 which is a ridge waveguide, a mechanical interference occurs where the branch circuit cannot be arranged between adjacent waveguide slot subarrays 100. Also, if the waveguide width of the waveguides constituting the branch circuit is made small, as described above, the transmission characteristics of radio waves are impaired.

[0071] Therefore, in the waveguide slot array antenna 2 in the second embodiment, in the waveguide slot subarray 100, the radiating element sections 120 are bisected with different numbers. Fig. 13 is a diagram for explaining the waveguide slot array antenna 2 in the second embodiment. Fig. 13(a) is a diagram for explaining the waveguide slot array module 10 and the power feed module 40 in the waveguide slot array antenna 2, Fig. 13(b) is a perspective view of the waveguide slot array antenna 2, and Fig. 13(c) is a cross-sectional view taken along line XIIIC-XIIIC of Fig. 13(b). The directions in Figs. 13(a), (b), and (c) are as shown.

[0072] Similar to the waveguide slot array antenna 1 in the first embodiment, the waveguide slot array antenna 2 includes a waveguide slot array module 10, a radiation aperture module 20, and a beamforming module 30. And the waveguide slot array antenna 2 further includes a power feed module 40. Since the beamforming module 30 is the same as that described in the first embodiment, the description thereof will be omitted below.

[0073] As shown in Fig. 13(b), the waveguide slot array antenna 2 is configured by stacking, in the z direction, a power feeding module 40, a waveguide slot array module 10, and a radiation aperture module 20 in this order. A beam forming module 30 (not shown) for which the explanation is omitted is stacked on the -z direction side (back side) of the power feeding module 40. The power feeding module 40, the waveguide slot array module 10, the radiation aperture module 20, and the beam forming module 30 are fixed by a fixing mechanism 50 (see Fig. 1).

[0074] Fig. 13(a) shows only the waveguide slot array module 10 and the power feeding module 40 in order to show the relationship between the waveguide slot array module 10 and the power feeding module 40 in the waveguide slot array antenna 2. In Fig. 13(a), the waveguide slot array module 10 is shown in a perspective view from the side of the waveguide slot array module 10. Note that the notation of the ridge portion 117 is omitted.

[0075] The waveguide slot array antenna 2 includes eight waveguide slot sub-arrays 100 in which the y direction is the longitudinal direction and the x direction is the short side direction. Each waveguide slot sub-array 100 includes nine radiation element portions 120 in the y direction. When distinguishing the waveguide slot sub-arrays 100, numbers are added for distinction, such as waveguide slot sub-array 100-1, 100-2, 100-3. The power feeding waveguide 43 that feeds power to the waveguide slot sub-array 100 is provided in each waveguide slot sub-array 100. When distinguishing the power feeding waveguides 43, numbers are added for distinction, such as power feeding waveguide 43-1, 43-2, 43-3. The same applies to other cases. The waveguide slot sub-array 100, which is a ridge waveguide, may be referred to as the first line, and the power feeding waveguide 43 may be referred to as the second line.

[0076] The number of radiating element parts 120 in the waveguide slot subarray 100 is nine. The radiating element parts 120 of the waveguide slot subarray 100-1 are divided into two such that there are five on the -y direction side and four on the +y direction side. A branch circuit 150-1 is provided between the five radiating element parts 120 and the four radiating element parts 120. The radiating element parts 120 of the waveguide slot subarray 100-2 adjacent to the waveguide slot subarray 100-1 are divided into two such that there are four on the -y direction side and five on the +y direction side. A branch circuit 150-2 is provided between the four radiating element parts 120 and the five radiating element parts 120. When not distinguishing between the branch circuits 150-1 and 150-2, they are denoted as the branch circuit 150.

[0077] By arranging the waveguide slot subarrays 100 with different positions of the radiating element parts 120 divided as described above in an alternating parallel arrangement, the branch circuit 150 does not have the same (overlapping) position in the y direction between adjacent waveguide slot subarrays 100. Then, if the power supply waveguide 43, which is a waveguide for power supply connected to the branch circuit 150, is extended along the longitudinal direction of the waveguide slot subarray 100 to the side with fewer radiating element parts 120, the power supply waveguides 43 do not adjacent to each other between adjacent waveguide slot subarrays 100. Therefore, it is suppressed that the waveguide width of the power supply waveguide 43 is restricted by the waveguide width of the waveguide slot subarray 100 which is a ridge waveguide. When the radiating element parts 120 are divided into different numbers, power distribution according to the number of the divided radiating element parts 120 is required in the branch circuit 150.

[0078] As shown in FIG. 2, the beamforming module 30 supplies an RF signal from the +y direction end or the -y direction end. Therefore, an input / output port 190 is provided at the +y direction end or the -y direction end of the power supply module 40 (see FIG. 13(c)).

[0079] In the above description, the number of radiation element parts 120 in the waveguide slot sub-array 100 is set to an odd number and divided so that the difference is one. The number of radiation element parts 120 in the waveguide slot sub-array 100 may be set to an even number and divided into two parts so that the difference is two. The smaller the difference, the easier the power distribution. The number of radiation element parts 120 to be divided may be set according to the power distribution. In order to avoid the performance of the waveguide slot sub-array 100 to be divided being biased to one side, the number of the divided radiation element parts 120 is preferably close. The difference in the number of radiation element parts 120 is preferably one.

[0080] As shown in FIG. 13(c), in the z direction, the power supply module 40, the waveguide slot array module 10, and the radiation aperture module 20 are superimposed. The waveguide slot sub-array 100 in the waveguide slot array module 10 includes a ridge part 117, a slot 121, a first matching element 132, and a second matching element 133, similar to the waveguide slot array antenna 1 described in the first embodiment.

[0081] The power supply module 40 is composed of two types of plate-like members 41 and 42. The power supply waveguide 43 is composed of a groove (slot) provided in the plate-like member 42, the broad wall 111 constituting the waveguide slot sub-array 100 as one broad wall (+z direction side broad wall), and the plate-like member 41 as the other broad wall (-z direction side broad wall). The power supply waveguide 43 is a waveguide with a rectangular cross-section. One end of the power supply waveguide 43 extends to the power supply aperture 151 provided in the broad wall 111, and the other end of the power supply waveguide 43 extends to the +y direction end of the waveguide slot sub-array 100. An input / output port 190 is provided in the plate-like member 41 at the other end of the power supply waveguide 43. The input / output port 190 has the same function as the input / output port 190 provided in the waveguide slot sub-array 100 of the waveguide slot array antenna 1, and performs input / output of RF signals with the beam forming module 30 provided on the back surface (-z direction side) of the power supply module 40. Therefore, the same reference numerals are used.

[0082] The waveguide slot array module 10 and the power feeding module 40 are overlapped. That is, the waveguide slot sub-array 100 in the waveguide slot array module 10 and the power feeding waveguide 43 in the power feeding module 40 are provided back to back.

[0083] Considering forming the power feeding module 40 by diffusion bonding, the fewer the types of production plates (types of patterns) constituting the thin plate member, the better. As shown in FIG. 13(c), by configuring the power feeding waveguide 43 and the input / output port 190 in an L shape, the types of production plates can be reduced to two types: the pattern of the groove that becomes the power feeding waveguide 43 in the plate member 42 and the pattern including the power feeding waveguide 43's wide wall on the -z direction side and the input / output port 190 in the plate member 41.

[0084] Next, the configuration of the branching circuit 150 that branches the waveguide slot sub-array 100 into two will be described. Here, it is assumed that the waveguide slot sub-array 100 shown in FIG. 13(a) has 9 radiation element parts 120 and is divided into 4 and 5.

[0085] FIG. 14 is a diagram for explaining the configuration of the branching circuit 150A in the waveguide slot sub-array 100. FIG. 14(a) is a plan view showing the configuration of the branching circuit 150A, and FIG. 14(b) is a perspective view of the waveguide slot array module 10. Note that FIGS. 14(a) and (b) are shown excluding the wide wall 112 where the slots 121 of the waveguide slot sub-array 100 are provided. The directions in FIGS. 14(a) and (b) are as shown.

[0086] As shown in FIG. 14(a), the branching circuit 150A is composed of structure I and structure II sandwiching the power feeding opening 151. In the waveguide slot sub-array 100, structure I is on the side with a larger number of radiation element parts 120, and structure II is on the side with a smaller number of radiation element parts 120. The ridge part 117 is divided by the power feeding opening 151. The ridge part 117 on the structure I side is denoted as the ridge part 117a, and the ridge part 117 on the structure II side is denoted as the ridge part 117b.

[0087] In Structure I, the ridge portion 117a is provided up to the power supply opening 151. In Structure I, a matching element 153 is provided on the narrow wall 113 and a matching element 154 is provided on the narrow wall 114 at the end of the power supply opening 151. The matching elements 153 and 154 may be in contact with the power supply opening 151, or a gap may be provided. The matching elements 153 and 154 are the same as the matching element 131 called a so-called iris provided in the conventional waveguide slot subarray 100' (see Fig. 3(b)). The matching element 153 is provided on the narrow wall 113 so as to connect the wide walls 111 and 112 (see Fig. 3(b)). The matching element 154 is provided on the narrow wall 114 so as to connect the wide walls 111 and 112.

[0088] In Structure II, a gap is provided between the ridge portion 117b and the power supply opening 151. The gap may be denoted as an offset P. Structure II does not include matching elements such as the matching elements 153 and 154. As described above, the power supply waveguide 43 extends to the side where the number of radiation element portions 120 is small, that is, the Structure II side (see Fig. 13(a)).

[0089] Fig. 15 is a diagram for explaining the branch circuit 150B in the power supply module 40. Fig. 15(a) is a perspective view of the power supply module 40, and Fig. 15(b) is an enlarged view showing the connection portion with the branch circuit 150A (see Fig. 14(a)) of the waveguide slot subarray 100. The directions in Figs. 15(a) and 15(b) are as shown.

[0090] The power supply waveguide 43 in the power supply module 40 includes a waveguide portion 43a and a matching portion 43b. As shown in Fig. 15(a), the matching portion 43b faces the power supply opening 151 in the branch circuit 150A of the waveguide slot subarray 100. The tube width W4 of the matching portion 43b is wider than the tube width W3 of the waveguide portion 43a. This is for matching the power supply waveguide 43 (waveguide portion 43a), which is a waveguide, with the waveguide slot subarray 100, which is a ridge waveguide. The branch circuit 150 combines the branch circuit 150A of the waveguide slot sub-array 100 and the matching portion 43b of the feed waveguide 43, and has a conversion function from a waveguide to a ridge waveguide and a conversion function from a ridge waveguide to a waveguide.

[0091] As described above, when the waveguide slot sub-array 100 including nine radiating element portions 120 is divided into a group of five radiating element portions 120 and a group of four radiating element portions 120, the power distribution ratio is required to be 5:4. That is, the power supplied to the side of the five radiating element portions 120 is 1.25 times the power supplied to the side of the four radiating element portions 120. Here, the conversion characteristics were simulated for the case where the power distribution ratio is 3:2. This is because in order to suppress the side lobes low, it is preferable to set the power distribution ratio to be greater than the ratio of the number of the radiating element portions 120. When the power distribution ratio is 3:2, the power supplied to the side of the five radiating element portions 120 becomes 1.5 times the power supplied to the side of the four radiating element portions 120.

[0092] FIG. 16 is a diagram for explaining the configuration of the branch circuit 150 used for evaluating the branching characteristics. FIG. 16(a) is a perspective view of the branch circuit 150, FIG. 16(b) is a perspective view of the branch circuit cut along the broken line in FIG. 16(a), and FIGS. 16(c), (d), and (e) are plan views of the branch circuit A having different configurations used for evaluating the branching characteristics. The directions in FIGS. 16(a) to (e) are as shown.

[0093] FIG. 16(a) shows a branch circuit 150 configured using the branch circuit 150A in the waveguide slot subarray 100 shown in FIG. 14 and the matching portion 43b of the feeding waveguide 43 in the feeding module 40 shown in FIG. 15. FIG. 16(a) shows the branch circuit 150 as viewed from the structure I side shown in FIG. 14(a). As shown in FIG. 16(b), in the cross section along the dashed line in FIG. 16(a), on the structure I side, the ridge portion 117a is provided up to the feeding aperture 151. And on the structure I side, a matching element 153 is provided adjacent to the feeding aperture 151. On the other hand, on the structure II side, the ridge portion 117b is provided offset by P from the feeding aperture 151. As shown in FIG. 16(b), the structure I side is Port2, the structure II side is Port3, and the feeding waveguide 43 side is Port1.

[0094] FIG. 16(c) shows the branch circuit 150A shown in FIG. 14(a) and has the configuration shown in FIGS. 14(a) and (b). This is denoted as model D. FIG. 16(d) shows that the structure II side in FIG. 14(a) has the same configuration as structure I. Structure I is provided on both sides with the feeding aperture 151 in between. This is denoted as model E. FIG. 16(e) shows a configuration obtained by excluding the matching elements 153 and 154 from the model A in FIG. 16(c). This is denoted as model F.

[0095] FIG. 17 shows the results of evaluating the characteristics of the branch circuit 150. FIG. 17(a) shows the power distribution ratio between Port2 and Port3, and FIG. 17(b) shows the reflection characteristics at Port1. In FIGS. 17(a) and (b), the horizontal axis is the frequency [GHz]. The vertical axis in FIG. 17(a) is the power distribution ratio, which is the square of the ratio of the transmission parameter S21 from Port1 to Port2 and the transmission parameter S31 from Port1 to Port3 (|S21 / S31| 2 ). The vertical axis in FIG. 17(b) is S11 [dB] indicating the reflection characteristics at Port1.

[0096] As shown in Fig. 17(a), in model D, the power distribution ratio is 1.5, which is consistent with the set value. And in model D, in the frequency range from 56 GHz to 64 GHz, the frequency dependence is small. On the other hand, in model E, the power distribution ratio is 1, and different powers cannot be supplied to Port2 and Port3. However, in model E, in the above frequency range, the frequency dependence is small. In model F, the power distribution ratio ranges from 1.3 to 1.8, but in the above frequency range, the frequency dependence is large.

[0097] From the results of model D and model E, it can be seen that by providing an offset P between the ridge portion 117 and the power supply opening 151, the power distribution ratio can be adjusted. And from the results of model D and model E, it can be seen that by providing matching elements 153 and 154 called so-called irises, adjustment of the power distribution ratio and improvement of the frequency characteristics can be achieved.

[0098] Fig. 18 is an example of an overall view of pattern B (see Fig. 5(a)) including the ridge portion 117 of the waveguide slot array antenna 2 in the second embodiment. The ridge portion 117 is divided into ridge portions 117a and 117b.

[0099] Fig. 19 is a diagram showing the radiation characteristics when the main beam is directed in the front direction in the waveguide slot array antenna 2 of the second embodiment. Fig. 19(a) is the radiation pattern, and Fig. 19(b) is the reflection characteristic. The directions in Fig. 19(a) are as shown. In Fig. 19(b), the horizontal axis is the frequency [GHz], and the vertical axis is the reflection characteristic S11 [dB].

[0100] As shown in Fig. 19(a), Port1 to Port8 were set. The RF signal that excites the waveguide slot sub-array 100 was supplied from the power feeding module 40 through the above-described branch circuit 150. With the excitation conditions for each Port being the same, the radiation characteristics of the waveguide slot array antenna 1 were obtained by simulation. The excitation conditions in each waveguide slot sub-array 100 were the same. That is, the phase condition of the RF signal supplied to each waveguide slot sub-array 100 was set so that the main beam would be directed in the front direction (z direction), which is the direction perpendicular to the waveguide slot array antenna 1. Therefore, in the radiation pattern, the main beam is directed in the front (z direction), which is the direction perpendicular to the waveguide slot array antenna 1.

[0101] As shown in Fig. 19(b), S11 indicating the reflection characteristics at Port1, 4, and 8 is -10 dB or less at frequencies from 56 GHz to 64 GHz.

[0102] Fig. 20 is a diagram for explaining the directivity when the main beam of the waveguide slot array antenna 2 in the second embodiment is directed in the front direction. Fig. 20(a) shows the vertical plane directivity, and Fig. 20(b) shows the horizontal plane directivity. In the graphs of Fig. 20(a) and (b), the horizontal axis represents the angle [°], and the vertical axis represents the relative gain [dB]. Also, the main beam direction [°], the half-power beamwidth [°], and the directivity gain [dB] are shown in a table.

[0103] The vertical plane directivity and the horizontal plane directivity shown in Fig. 20(a) and (b) are almost the same at 58 GHz, 60 GHz, and 62 GHz, and have little frequency dependence. Also, the main beam direction is 0°, the half-power beamwidth is approximately 9° in the vertical plane directivity and approximately 10° in the horizontal plane directivity, which is narrow, and the difference with frequency is small. That is, the waveguide slot array antenna 2 has the same characteristics as the waveguide slot array antenna 1 and can be used in these frequency ranges.

[0104] FIG. 21 shows the radiation characteristics of the waveguide slot array antenna 2 according to the second embodiment when the main beam is directed from the front direction to the -26° direction in the horizontal plane by phase control of each waveguide slot sub-array 100. FIG. 21(a) shows the radiation pattern at 58 GHz, FIG. 21(b) shows the radiation pattern at 60 GHz, FIG. 21(c) shows the radiation pattern at 62 GHz, and FIG. 21(d) shows the directivity in the horizontal plane. The directions in FIGS. 21(a), (b), and (c) are as shown. In the graph of FIG. 21(d), the horizontal axis represents the angle [°], and the vertical axis represents the relative gain [dB].

[0105] The phase condition of the RF signal supplied to each waveguide slot sub-array 100 is set (phase-controlled) so that the main beam of the waveguide slot array antenna 2 is directed in the -26° direction in the horizontal plane. As shown in FIG. 21(d), the direction of the main beam is approximately -26° at frequencies 58 GHz, 60 GHz, and 62 GHz, and the half-power beamwidth is approximately 11°. There is little difference from the radiation characteristics when the main beam is directed in the front direction shown in FIG. 20. That is, the waveguide slot array antenna 2 is an antenna capable of beamforming in the 60 GHz band. And the waveguide slot array antenna 2 to which the second embodiment is applied can be manufactured with high precision by diffusion bonding. Further, as shown in FIGS. 21(a), (b), and (c), the grating lobes are suppressed to be smaller even at frequencies other than the design frequency compared to the waveguide slot array antenna 1 in the first embodiment. That is, the waveguide slot array antenna 2 in the second embodiment has a wider bandwidth compared to the waveguide slot array antenna 1 in the first embodiment.

[0106] The waveguide slot array antenna 2 in the second embodiment is a thin antenna configured in a flat plate shape that is thicker by the thickness of the power supply module 40 than the waveguide slot array antenna 1 in the first embodiment, but can control the power distribution ratio.

[0107] Although the embodiments of the present invention have been described above, the technical scope of the present invention is not limited to the scope described in the above embodiments. It is obvious from the description of the claims that those obtained by making various changes or improvements to the above embodiments are also included in the technical scope of the present invention. Furthermore, various modifications may be made as long as they do not contravene the spirit of the present invention.

Explanation of Reference Numerals

[0108] 1, 2... waveguide slot array antennas, 10... waveguide slot array module, 20... radiation aperture module, 30... beamforming module, 32... beamforming circuit, 40... power feeding module, 43... power feeding waveguide, 50... fixing mechanism, 100, 100′... waveguide slot sub-arrays, 117, 117a, 117b... ridge portions, 120... radiation element portion, 121... slot, 131, 153, 154... matching elements, 132... first matching element, 133... second matching element, 140... converter, 141... taper portion, 150, 150-1, 150-2, 150A, 150B... branch circuits, 190... input / output port

Claims

1. A waveguide slot array antenna in which a plurality of waveguide slot subarrays are arranged in parallel, The waveguide slot subarray comprises: A waveguide having a rectangular cross section, the waveguide being surrounded by two wide walls facing each other and two narrow walls connecting the two wide walls and narrower than the wide walls, the waveguide having a rectangular cross section, a plurality of slots in one of the broad walls; a ridge portion provided on the other broad wall; a first matching element, on the other of the wide walls, having the same thickness as the ridge portion and connecting the ridge portion and the narrow wall; A waveguide slot array antenna comprising:

2. 2. The waveguide slot array antenna according to claim 1, further comprising a second matching element provided on the narrow wall to connect between the two wide walls or to connect between the first matching element and a wide wall opposite to the wide wall on which the first matching element is provided.

3. 2. The waveguide slot array antenna according to claim 1, further comprising a transducer having a tapered section connected to the ridge section and gradually widening in width from the ridge section on the wide wall on which the ridge section is provided, and two narrow walls having a space between them that gradually widens from the space between the narrow walls to which the tapered section is connected.

4. 3. The waveguide slot array antenna according to claim 1, wherein the plurality of waveguide slot subarrays in the waveguide slot array antenna are serially fed from input / output ports provided at the ends of the slots, and are arranged in parallel such that the input / output ports are staggered in the longitudinal direction of the waveguide slot subarrays in the direction of the adjacent waveguide slot subarrays.

5. The waveguide slot array antenna according to claim 4, further comprising a wiring board on the opposite side to the side on which the slots are provided, the wiring board having a beam forming circuit for forming beams of the waveguide slot array antenna, and a signal for controlling beam forming is supplied to the input / output port.

6. creating a plurality of thin plate members parallel to the broad wall, which are stacked together to form the waveguide slot array antenna of claim 1; a step of overlapping a plurality of the thin plate members, and heating the thin plate members at a temperature equal to or lower than the melting point of the thin plate members while applying pressure to the thin plate members, thereby diffusion bonding the plurality of the thin plate members; A method for manufacturing a waveguide slot array antenna, comprising:

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