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

Abstract

To provide a high-gain waveguide slot array antenna with beamforming capability, comprising a ridge portion satisfying the conditions for diffusion bonding manufacturing.SOLUTION: A waveguide slot array antenna includes multiple waveguide slot sub-arrays arranged in parallel. Each waveguide slot sub-array is a waveguide of a square cress-section surrounded by mutually facing two wide walls and mutually facing two narrow walls that connect the two wide walls and are narrower than the wide walls, and includes a plurality of slots provided on one wide wall, a ridge portion provided on the other wide wall, and a first matching element on the other wide wall, having the same thickness as the ridge portion and connecting the ridge portion to the narrow walls.SELECTED DRAWING: Figure 6

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 technology]

[0002] Non-Patent Document 1 describes that in a two-layer slot waveguide antenna manufactured by stacking thin metal plates formed by etching and then diffusion bonding them, the number of metal plates to be stacked can be reduced by supplying alternating phases. [Prior art documents] [Non-patent literature]

[0003] [Non-Patent Document 1] M. ZNANG, J. HIROKAWA, and M. ANDO, “A Partially-Corporate Feed Double-Layer Waveguide Slot Array with the Sub-arrays also Fed in Alternating-Phases”, IEICE TANS. COMMUN. Vol.E97-B, No.2, 2014, pp.469-475. Summary of the Invention [Problem to be solved by the invention]

[0004] Achieving long-distance communications using millimeter waves requires antennas with high gain. When an antenna is designed using a printed circuit board, it is easy to integrate it with a beamforming module configured on the printed circuit board, but it is not suitable for achieving high gain due to losses in the transmission line. Waveguides, which have low loss, are suitable for achieving high gain. Given the transmission conditions of the waveguide and the conditions for beamforming, a ridge waveguide is suitable. When manufacturing a ridge waveguide using diffusion bonding, it is difficult for the ridge portion of the ridge waveguide to meet the manufacturing conditions for diffusion bonding. An object of the present invention is to provide a high-gain waveguide slot array antenna or the like that satisfies the conditions for manufacturing a ridge portion by diffusion bonding and has a beamforming function. [Means for solving the problem]

[0005] The invention described in claim 1 is a waveguide slot array antenna in which a plurality of waveguide slot subarrays are arranged in parallel, wherein the waveguide slot subarray is a waveguide with a rectangular cross section surrounded by two wide walls facing each other and two narrow walls connecting the two wide walls and facing each other and narrower than the wide walls, and the waveguide slot array antenna comprises 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 on the other wide wall, having the same thickness as the ridge portion and connecting the ridge portion to the narrow wall. The invention described in claim 2 is a waveguide slot array antenna described in claim 1, further comprising a second matching element provided on the narrow wall and connecting the two wide walls, or connecting the first matching element and a wide wall opposite to the wide wall on which the first matching element is provided. The invention described in claim 3 is the waveguide slot array antenna described in claim 1, comprising a converter having, on a wide wall on which the ridge portion is provided, a tapered portion connected to the ridge portion and gradually widening in width from the ridge portion, and two narrow walls to which the tapered portion is connected and whose spacing gradually widens from the spacing between the narrow walls. The invention described in claim 4 is a waveguide slot array antenna described in claim 1 or 2, wherein the multiple waveguide slot subarrays in the waveguide slot array antenna are serially fed to the slots from input / output ports provided at the ends, and are arranged in parallel in the direction of adjacent waveguide slot subarrays so that the input / output ports are positioned alternately in the longitudinal direction of the waveguide slot subarrays. The invention described in claim 5 is the waveguide slot array antenna according to claim 4, wherein the waveguide slot array antenna includes a wiring board on the side opposite 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. The invention described in claim 6 is a method for manufacturing a waveguide slotted array antenna, comprising: a step of creating a plurality of thin plate members parallel to the wide wall, which become the waveguide slotted array antenna described in claim 1 by overlapping them; and a step of overlapping the plurality of thin plate members, heating them at a temperature equal to or lower than the melting point of the thin plate members while applying pressure, and diffusion bonding the plurality of thin plate members. [Effects of the Invention]

[0006] According to the invention of claim 1, the ridge portion satisfies the conditions for manufacturing by diffusion bonding, and a high-gain waveguide slot array antenna having a beamforming function can be obtained. According to the invention as recited in claim 2, the inductance can be adjusted more easily than when the second matching element is not provided. According to the invention as set forth in claim 3, reflection between the waveguide that performs the feeding and the ridge waveguide that is the waveguide slot subarray is suppressed compared to when no converter is used. According to the invention as set forth in claim 4, the change in the direction of the beam radiated by the waveguide slot array antenna is suppressed compared to when the beams are not staggered. According to the invention of claim 5, the waveguide slot array antenna can be configured in a flat plate shape compared to when the beam forming circuit is not provided on the wiring board. According to the invention as set forth in claim 6, a waveguide slot array antenna using a ridge waveguide can be manufactured by diffusion bonding. [Brief explanation of the drawings]

[0007] [Figure 1]1A and 1B are diagrams illustrating an example of a waveguide slot array antenna to which the first embodiment is applied, where (a) is a plan view and (b) is a side view. [Figure 2] FIG. 1 is a perspective view of a waveguide slot array antenna as seen from the rear side. [Figure 3] 1A and 1B are diagrams illustrating a conventional waveguide slot subarray with a ridge portion, together with problems that arise when manufacturing the waveguide slot subarray by diffusion bonding. (a) is a cross-sectional view of the conventional waveguide slot subarray, (b) is a perspective view of the conventional waveguide slot subarray with the broad wall removed, and (c) is a perspective view of a thin plate member B of pattern B including the ridge portion of the conventional waveguide slot subarray. [Figure 4] 1A and 1B are diagrams illustrating the configuration of a waveguide slot subarray according to a first embodiment, in which (a) is a perspective view of the appearance of a waveguide slot subarray according to the first embodiment and a conventional waveguide slot subarray, (b) is a perspective view of the conventional waveguide slot subarray with wide walls indicated by dashed lines, and (c) is a perspective view of the waveguide slot subarray according to the first embodiment with wide walls indicated by dashed lines. [Figure 5] 1A and 1B are diagrams illustrating a method for manufacturing a waveguide slot subarray having a ridge portion according to a first embodiment by diffusion bonding, in which (a) is a diagram illustrating patterns A, B, C, and D of thin plate members used in manufacturing the waveguide slot subarray, and (b) is a diagram illustrating the state in which the thin plate members are stacked and diffusion bonded. [Figure 6] FIG. 2 is a perspective view of an example of a waveguide slot subarray in the first embodiment. [Figure 7]10A and 10B are diagrams illustrating radiation performance when a first matching element and a second matching element are provided: (a) is a perspective view of the appearance of one radiating element unit, (b) is a perspective view of a radiating element unit (model A) in a conventional waveguide slot subarray using matching elements, (c) is a perspective view of a radiating element unit (model B) using one first matching element and one second matching element in a waveguide slot subarray of the first embodiment, (d) is a perspective view of another radiating element unit (model C) using one first matching element and one second matching element in a waveguide slot subarray of the first embodiment, and (e) is the reflection characteristics of each model. [Figure 8] 1A and 1B are diagrams illustrating a converter according to a first embodiment, in which (a) is a perspective view of a waveguide slot sub-array with a broad wall removed, and (b) is a perspective view of a thin plate member B including a converter portion. [Figure 9] 1A and 1B are diagrams illustrating the conversion characteristics of a converter, in which (a) is a perspective view of the converter, (b) is a perspective view of the converter cut along the dashed line in (a), and (c) is a reflection characteristic showing the conversion characteristics of the converter. [Figure 10] 1A and 1B are diagrams illustrating radiation characteristics when the main beam is directed in the forward direction in the waveguide slot array antenna according to the first embodiment, where (a) shows the radiation pattern and (b) shows the reflection characteristics. [Figure 11] 1A and 1B are diagrams illustrating directivities when the main beam of the waveguide slot array antenna according to the first embodiment is directed forward, where (a) shows directivity in a vertical plane and (b) shows directivity in a horizontal plane. [Figure 12] 1 shows radiation characteristics when the main beam is directed in the horizontal plane at an angle of -26° from the front direction by phase control of each waveguide slot subarray in the waveguide slot array antenna of the first embodiment. (a) shows the radiation pattern at 58 GHz, (b) shows the radiation pattern at 60 GHz, (c) shows the radiation pattern at 62 GHz, and (d) shows the directivity in the horizontal plane. [Figure 13]10A and 10B are diagrams illustrating a waveguide slot array antenna according to a second embodiment, in which (a) is a diagram illustrating a waveguide slot array module and a power supply module in the waveguide slot array antenna, (b) is a perspective view of the waveguide slot array antenna, and (c) is a cross-sectional view taken along line XIIIC-XIIIC in (b). [Figure 14] 1A and 1B are diagrams illustrating the configuration of a branching circuit in a waveguide slot subarray, where (a) is a plan view showing the configuration of the branching circuit, and (b) is a perspective view of a waveguide slot array module. [Figure 15] 10A and 10B are diagrams illustrating a branch circuit B in a power supply module, in which (a) is a perspective view of the power supply module, and (b) is an enlarged view showing a connection portion between the waveguide slot subarray and the branch circuit A. [Figure 16] 1A and 1B are diagrams illustrating the configuration of a branch circuit used to evaluate branch characteristics: (a) is a perspective view of the branch circuit, (b) is a perspective view of the branch circuit cut along the dashed line in (a), and (c), (d), and (e) are plan views of branch circuits A with different configurations used to evaluate branch characteristics. [Figure 17] The results of evaluating the characteristics of the branch circuit are shown in (a) and (b). [Figure 18] FIG. 10 is an example of an overall view of a pattern B including a ridge portion of a waveguide slot array antenna according to a second embodiment. [Figure 19] 10A and 10B are diagrams illustrating radiation characteristics when the main beam is directed forward in the waveguide slot array antenna according to the second embodiment, where (a) shows the radiation pattern and (b) shows the reflection characteristics. [Figure 20] 10A and 10B are diagrams illustrating directivities when the main beam of the waveguide slot array antenna according to the second embodiment is directed forward, where (a) shows directivity in a vertical plane and (b) shows directivity in a horizontal plane. [Figure 21]10A and 10B are diagrams showing radiation characteristics of the waveguide slot array antenna of the second embodiment when the main beam is directed in the horizontal plane at an angle of -26° from the front direction by phase control of each waveguide slot subarray. (a) shows the radiation pattern at 58 GHz, (b) shows the radiation pattern at 60 GHz, (c) shows the radiation pattern at 62 GHz, and (d) shows the directivity in the horizontal plane. DETAILED DESCRIPTION OF THE INVENTION

[0008] Hereinafter, an embodiment of the present invention will be described in detail with reference to the accompanying drawings. Note that the same reference numerals may be used for components having similar functions. Also, some components may be given reference numerals, while similar components may not be given reference numerals.

[0009] When the communication target is moving, such as in mobile communications, the antenna is required to have a beamforming function. Such antennas are required to be able to change the beam direction over a wide range in the direction parallel to the ground (horizontal direction).

[0010] The circuit (beamforming module) that controls the RF signal that executes beamforming is mounted on a wiring board, or so-called printed circuit board. In other words, the beamforming module is flat. To connect and integrate the antenna and beamforming module without using a cable (cableless), it is preferable that the antenna is also flat. Mounting the antenna on a wiring board such as a printed circuit board makes it easy to integrate it with the beamforming module, but it is difficult to achieve high gain due to losses in the transmission line. Waveguides have low loss, so they can achieve high gain. Therefore, a flat antenna was realized by using a waveguide with multiple slots as a subarray and arranging multiple subarrays in parallel. This antenna is called a waveguide slot array antenna, and the subarray is called a waveguide slot subarray.

[0011] (First embodiment) FIG. 1 is a diagram illustrating an example of a waveguide slot array antenna 1 to which a 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 on the paper surface is the x direction, the upward direction on the paper surface is the y direction, and the surface direction on the paper surface is the z direction. In FIG. 2(b), the left direction on the paper surface is the z direction, the upward direction on the paper surface is the y direction, and the surface direction on the paper surface is the x direction. In the following, the directions are as shown in the figure, and explanations 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 as the back side.

[0012] The waveguide slot array antenna 1 includes a waveguide slot array module 10. The waveguide slot array antenna 1 may include a radiating aperture module 20. The waveguide slot array antenna 1 may further include a beam forming module 30. As shown in FIG. 1(b), the radiating aperture module 20 is provided on one side (here, the +z direction side) of the waveguide slot array module 10. The beam forming module 30 is provided on the other side (here, the -z direction side, opposite the side on which slots 121, described later, are provided) of the waveguide slot array module 10. The waveguide slot array module 10, the radiating aperture module 20, and the beam forming module 30 are all configured in a flat plate shape. By overlapping the waveguide slot array module 10, the radiating aperture module 20, and the beam forming module 30 and fixing them with a fixing mechanism 50 such as a screw, the waveguide slot array antenna 1 including the radiating aperture module 20 and the beam forming 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 (not shown). The hole is provided so as to penetrate the waveguide slot array module 10, the radiating aperture module 20, and the beam forming module 30. By passing a bolt through the hole and tightening it with a nut, the waveguide slot array module 10, the radiating aperture module 20, and the beam forming module 30 are integrated. Note that the fixing mechanism 50 may have other configurations. Below, a description of the fixing mechanism 50 will be omitted.

[0014] The waveguide slot array antenna 1 has a y direction perpendicular to the earth's surface (vertical direction) and an x ​​direction parallel to the earth's surface (horizontal direction). The waveguide slot array antenna 1 radiates radio waves in the +z direction. In the vertical direction, the waveguide slot array antenna 1 radiates beam-shaped radio waves whose radiation direction does not change (is fixed) and whose angular spread is small. In the horizontal direction, the waveguide slot array antenna 1 changes the radiation direction over a wide range using the beamforming module 30. Here, radiation will be described, but generally, an antenna can radiate and receive radio waves. Note that the waveguide slot array antenna 1 has a y direction perpendicular to the earth's surface and an x ​​direction parallel to the earth's surface, but the x and y directions may be different.

[0015] As shown in FIG. 1(a), the waveguide slot array module 10 includes multiple waveguide slot subarrays 100. The waveguide slot subarrays 100 are waveguides whose ±y directions are transmission paths for radio waves. The waveguide slot array module 10 is configured by arranging multiple waveguide slot subarrays 100 in the x direction. To distinguish the waveguide slot subarrays 100, they are denoted as waveguide slot subarrays 100-1, 100-2, ..., 100-8 in order in the x direction, as shown in FIG. 1(a). The waveguide slot array antenna 1, as an example, is configured with eight waveguide slot subarrays 100.

[0016] The waveguide slot subarray 100 in the waveguide slot array antenna 1 includes eight radiating element sections 120. The waveguide slot array module 10 includes a slot 121 as an example of a radiating element for each radiating element section 120. The slot 121 has a longitudinal direction and a lateral direction. The longitudinal direction of the slot 121 faces the longitudinal direction of the waveguide slot subarray 100. In the waveguide slot subarray 100, the slots 121 arranged in the y direction are alternately shifted in the ±x directions. Here, the waveguide slot subarray 100 is virtually divided into slots 121 in the longitudinal direction, and a portion including one divided slot 121 is referred to as a radiating element section 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 emits radio waves from the slot 121 through the radiation aperture 21. By using the radiation aperture 21, the reflection characteristics become broader in bandwidth compared to when the radiation aperture 21 is not used. Note that the waveguide slot array antenna 1 does not necessarily need to include the radiation aperture module 20. The radiation aperture module 20 is formed by etching or the like on a flat plate of metal such as copper (Cu), aluminum (Al), or stainless steel (SUS), and has the radiation aperture 21 provided therein.

[0018] Fig. 2 is a perspective view of the waveguide slot array antenna 1 as seen from the back side. The directions in Fig. 2 are as shown. The waveguide slot array module 10, the radiating aperture module 20, and the beam forming module 30 are integrated by being superimposed, but Fig. 2 shows a state in which the waveguide slot array module 10 and the radiating aperture module 20 are superimposed, with the beam forming module 30 removed and shifted.

[0019] The back surface of the waveguide slot array module 10 is the back side (sometimes referred to as the outside) of a wide wall 111 (see FIG. 3 ) of the waveguide slot subarray 100, which will be described later. The wide wall 111 is provided with input / output ports 190 for RF signals. The input / output ports 190 are openings provided at the ends of the waveguide slot subarray 100. The waveguide slot subarrays 100 are serially fed from the input / output ports 190. The waveguide slot subarrays 100 are arranged in parallel, alternately in the ±y direction, so that the input / output ports 190 are not adjacent to each other between adjacent waveguide slot subarrays 100, for example, between the waveguide slot subarray 100-1 and the waveguide slot subarray 100-2 (see FIG. 1(a)). In other words, the waveguide slot subarrays 100 are arranged in parallel, alternately, so that their orientations are opposite to each other. This is because, when the input / output port 190 is a waveguide that does not have a ridge portion 117 (see FIG. 3 described later), the waveguide that constitutes the input / output port 190 is set to have a wide pipe width. Therefore, by arranging the input / output ports 190 alternately, mechanical interference between adjacent input / output ports 190 is avoided.

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

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

[0022] The input / output terminal 34 for RF signals is provided opposite the input / output port 190 of the waveguide slot array module 10. The waveguide slot array module 10, the radiating aperture module 20, and the beam forming module 30 are integrated by overlapping them and fixing them with a fixing mechanism 50. The beam forming module 30 and the waveguide slot array module 10 are connected without using wiring (cables).

[0023] In the following, one slotted waveguide subarray 100 will be selected and the explanation will be centered on that slotted waveguide subarray 100.

[0024] In order for radio waves to be transmitted through a waveguide with a rectangular cross section, the tube width must 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 spacing between the waveguide slot subarrays 100 is to half the wavelength (1 / 2λ), the wider the angular range of beamforming that becomes possible. Here, λ is the wavelength of the radio waves. In the first embodiment, in order to enable beamforming over a wide angular range, a ridge portion is provided so that radio waves can be transmitted even if the tube width is smaller than half the wavelength (1 / 2λ). By providing the ridge portion, the tube width is effectively widened.

[0025] Here, the waveguide slot array antenna 1 transmits and receives radio waves in the millimeter wave band, e.g., the 60 GHz band. The wavelength λ of 60 GHz radio waves is approximately 5 mm. Therefore, the spacing between the waveguide slot subarrays 100 is approximately 2.5 mm. Fabricating a waveguide slot array module 10 in which multiple waveguide slot subarrays 100 are arranged at minute spacings of approximately 2.5 mm is difficult using cutting or other methods used to fabricate waveguides with wavelengths λ longer than millimeter waves. Here, the waveguide slot subarrays 100 are fabricated by stacking plate-shaped members (hereinafter referred to as thin plate members) and diffusion bonding them. Diffusion bonding is a manufacturing method in which thin metal plate members patterned by etching or other methods are stacked and heated under pressure at a temperature below their melting point. The thin plate members are bonded by the diffusion of metal atoms between them. Diffusion bonding suppresses the occurrence of sagging, deformation, fillets, and the like that occur with welding, and allows the waveguide slot array module 10 to be manufactured with high precision.

[0026] Before describing the waveguide slotted subarray 100 according to the first embodiment, a conventional waveguide slotted subarray 100' will be described. 3A and 3B are diagrams illustrating a conventional waveguide slotted subarray 100′ having a ridge portion 117, along with problems that arise when manufacturing the same by diffusion bonding. Fig. 3A is a cross-sectional view of the conventional waveguide slotted subarray 100′, Fig. 3B is a perspective view of the conventional waveguide slotted subarray 100′ with the wide wall 112 removed, and Fig. 3C is a perspective view of a thin plate member B of pattern B including the ridge portion 117 of the conventional waveguide slotted subarray 100′.

[0027] As shown in FIG. 3(a), a conventional waveguide slotted subarray 100′ having a ridge portion 117 is a waveguide having a rectangular cross section in the xz plane. The waveguide slotted subarray 100′ has wide walls 111 and 112, narrow walls 113 and 114, end walls 115 and 116, and a ridge portion 117. The wide walls 111 and 112 are parallel to the xy plane and face each other. The narrow walls 113 and 114 are parallel to the zy plane and face each other, connecting the wide walls 111 and 112. The widths of the wide walls 111 and 112 are wider than the widths of the narrow walls 113 and 114. The wide wall 112 has a slot 121 through which radio waves are emitted. As shown in FIG. 3(b), the ridge portion 117 is provided on the wide wall 111 so as to extend in the y direction. End walls 115 and 116 shown in FIG. 3(b) will be described later.

[0028] In Figure 3(a), the dashed lines indicate the boundaries of the thin plate members that are overlapped when manufacturing a conventional waveguide slotted subarray 100' by diffusion bonding. The waveguide slotted subarray 100' is manufactured by overlapping, from the back side, a thin plate member A of pattern A that forms the wide wall 111, a thin plate member B of pattern B that forms the ridge portion 117 and narrow walls 113 and 114, a thin plate member C of pattern C that forms the narrow walls 113 and 114, and a thin plate member D of pattern D that forms the wide wall 112 with the slot 121. To avoid complexity, the symbols of the thin plate members and the patterns are the same. In Figure 3(a), the waveguide slotted 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, and D is processed by etching, for example, by creating a production plate for screen printing and etching a metal plate based on the resist formed through the production plate. Each pattern of the thin plate members A, B, C, and D may be created by creating a production plate for exposure instead of for screen printing. The fewer production plates there are, the lower the initial cost.

[0029] In diffusion bonding, as shown by the arrows in Figure 3(a), a predetermined number of thin plate members A, B, C, and D are stacked on top of each other, and then pressure is applied from above (the +z direction) and the thin plate members are heated to a temperature below their melting point, causing the metal elements to diffuse between the thin plate members and joining them together.

[0030] 3(b), the waveguide slot subarray 100′ viewed with the wide wall 112 removed has an input / output port 190 at the end in the −y direction, which is an opening formed by removing the wide wall 111. An end wall 115 connecting the narrow walls 113 and 114 is provided at the end in the −y direction, and an end wall 116 connecting the narrow walls 113 and 114 is provided at the end in the +y direction. In other words, 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 (referred to as pattern B in FIG. 3(c)) formed in the pattern B shown in FIG. 3(c) has portions that become narrow walls 113, 114, end walls 115, 116, and a ridge portion 117. In pattern B (thin plate member B), the portions that become the narrow walls 113, 114, end walls 115, 116, and ridge portion 117 are referred to as narrow walls 113, 114, end walls 115, 116, and ridge portion 117.

[0032] Here, it will be explained why 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), pressure is not applied to the ridge portion 117 indicated by α. In the case of the 60 GHz band, the width W of the ridge portion 117 is R is, for example, 0.6 mm, and the length L of the ridge portion 117 Ris, for example, 36 mm. The ridge portion 117 is a thin line. One end (the end in the +y direction) indicated by β is connected to the end wall 116 of the ridge portion 117 and is therefore unlikely to be displaced. On the other hand, the other end (the end in the -y direction) of the ridge portion 117 indicated by γ is not connected to the end wall 115 or the like and is therefore prone to being displaced. Therefore, the ridge portion 117 of the conventional waveguide slotted subarray 100' is not pressurized sufficiently and is prone to being displaced. This makes it difficult to manufacture the waveguide slotted subarray 100' with high precision.

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

[0034] There are two methods of exciting a waveguide slot subarray: standing wave excitation and traveling wave excitation. In standing wave excitation, matching is achieved by adjusting the admittance characteristics of the radiating element section 120 having 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 elements such as stubs and irises are provided for each radiating element section 120 having the slot 121 to achieve matching.

[0035] The waveguide slot subarray 100 in the first embodiment uses traveling wave excitation. The waveguide slot subarray 100 in the first embodiment suppresses insufficient pressure and misalignment of the ridge portion 117 by using a matching element. The waveguide slot subarray 100 according to the first embodiment will be described below in comparison with a conventional waveguide slot subarray 100'. Note that similar parts will be given the same reference numerals and descriptions thereof will be omitted.

[0036] FIG. 4 is a diagram illustrating the configuration of the waveguide slotted subarray 100 according to the first embodiment. FIG. 4(a) is a perspective view of the appearance of the waveguide slotted subarray 100 according to the first embodiment and a conventional waveguide slotted subarray 100′, FIG. 4(b) is a perspective view of the conventional waveguide slotted subarray 100′ with the wide wall 112 indicated by a dashed line, and FIG. 4(c) is a perspective view of the waveguide slotted subarray 100 according to the first embodiment with the wide wall 112 indicated by a dashed line. Three radiating element portions 120 are shown in FIGS. 4(a), (b), and (c). The directions in FIGS. 4(a), (b), and (c) are as shown.

[0037] As shown in FIG. 4(a), the waveguide slotted subarray 100 according to the first embodiment and the conventional waveguide slotted subarray 100' have similar appearances. Therefore, they are referred to as waveguide slotted subarrays 100 / 100'. In FIG. 4(a), slots 121 are provided in a wide wall 112. The wide wall 112 in which the slots 121 are provided is sometimes 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 component provided on the narrow wall 113 or the narrow wall 114 to connect the wide wall 111 and the wide wall 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 to adjust the inductance. Note that the amount by which the matching element 131 protrudes from the narrow wall 113 or 114 into the center of the waveguide (protrusion amount) is set according to the required inductance. Furthermore, if the required inductance is small, the matching element 131 may not be provided in the radiating element section 120. In FIG. 4(b), the cross-sectional shape of the tip of the matching element 131 protruding from the center of the waveguide is rounded, but it does not have to be rounded. The matching elements 131 in the conventional waveguide slot subarray 100′ are provided on the narrow walls 113 and 114 and are not connected to the ridge portion 117. In the conventional waveguide slot subarray 100′, even if the matching elements 131 are provided, the insufficient pressure and positional deviation of the ridge portion 117 described in FIGS. 3(a) and 3(c) cannot be suppressed.

[0039] The waveguide slot subarray 100 according to the first embodiment shown in FIG. 4(c) further comprises 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 provided on the wide wall 111 and is a member 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, sandwiching the ridge portion 117 therebetween. Furthermore, two first matching elements 132 are provided for all three radiating element portions 120 shown in FIG. 4(c). The first matching elements 132 reduce the cross-sectional area of ​​the waveguide from the wide wall 111 side to adjust inductance. The slotted waveguide subarray 100 is a ridge waveguide having a rectangular cross section in the xz 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 inside the waveguide, and is provided 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 farther 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, if the required inductance is small, the first matching element 132 may be provided only on one side (one side) of the ridge section 117. In this case, the second matching element 133 does not have to be provided so as to be connected to the first matching element 132. In other words, the second matching element 133 may be provided so as to connect the wide wall 111 and the wide wall 112, similar to the matching element 131 of the conventional waveguide slot subarray 100′. In the radiating element section 120, if the required inductance is even smaller, the first matching element 132 may not be provided.

[0042] The amount by which second matching element 133 extends from narrow walls 113 and 114 toward the center of the waveguide (extension amount) may be set depending on the required inductance, similar to matching element 131. If the required inductance is small, second matching element 133 does not need to be provided.

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

[0044] In the waveguide slot subarray 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 subarray 100 according to the first embodiment, the thin plate member B including the ridge portion 117 is different from the thin plate member B shown in FIG. 3( c) in that 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), the narrow walls 113 and 114 are pressurized, and the ridge portion 117 is also pressurized via the first matching element 132. The distance between the ridge portion 117 indicated by α and the narrow wall 113 and / or the narrow wall 114 is fixed by the first matching element 132, and positional deviation of the ridge portion 117 is suppressed.

[0045] Fig. 6 is a perspective view of an example of the waveguide slot subarray 100 according to the first embodiment. The directions in Fig. 6 are as shown in the figure. As shown in Fig. 6, the waveguide slot subarray 100 is configured by combining a first matching element 132 and a second matching element 133. As shown in Fig. 6, in the waveguide slot subarray 100, the first matching element 132 does not have to be provided in all the radiating element sections 120. Similarly, the second matching element 133 does not have to be provided in all the radiating element sections 120 of the waveguide slot subarray 100. The amount of protrusion of the second matching element 133 from the narrow wall 113 or the narrow wall 114 may differ between the radiating element sections 120. Also, there may be a radiating element section 120 that does not have the second matching element 133.

[0046] Next, the radiation performance of the waveguide slot subarray 100 when the first matching element 132 and the second matching element 133 are provided will be described. Fig. 7 is a diagram illustrating radiation performance when a first matching element 132 and a second matching element 133 are provided. Fig. 7(a) is a perspective view of the appearance of one radiating element section 120, Fig. 7(b) is a perspective view of a radiating element section 120 (model A) in a conventional waveguide slot subarray 100' using a matching element 131, Fig. 7(c) is a perspective view of a radiating element section 120 (model B) using one first matching element 132 and one second matching element 133 in the waveguide slot subarray 100 of the first embodiment, Fig. 7(d) is a perspective view of another radiating element section 120 (model C) using one first matching element 132 and one second matching element 133 in the waveguide slot subarray 100 of the first embodiment, and Fig. 7(e) shows the reflection characteristics of each model. Figures 7(b), (c), and (d) show radiating aperture module 20 and wide wall 112 (see Figure 4(a)) cut away by the dashed line shown in Figure 7(a). In Figures 7(b), (c), and (d), slot 121 is shown by the dashed line. The directions in Figures 7(a), (b), (c), and (d) are as shown.

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

[0048] FIG. 7(b) shows a radiating element section 120 (model A) in a conventional waveguide slot subarray 100', in which a matching element 131, so-called an iris, is provided on a narrow wall 113.

[0049] Figure 7(c) shows the radiating element section 120 (model B) in the waveguide slot subarray 100 of the first embodiment, in which a first matching element 132 is provided on the wide wall 112 on the narrow wall 114 side, and a second matching element 133 is provided on the narrow wall 113.

[0050] 7(d) shows another radiating element section 120 (model C) in the waveguide slot subarray 100 of the first embodiment, in which a first matching element 132 is provided on the wide wall 112 on the narrow wall 113 side, and a second matching element 133 is provided on the narrow wall 113. The second matching element 133 is provided overlapping the first matching element 132.

[0051] 7(e), the reflection characteristics of models B and C of the waveguide slot subarray 100 according to the first embodiment are equal to or better than those of model A of the conventional waveguide slot subarray 100′. That is, by providing the first matching element 132 so as to be connected to the ridge portion 117, insufficient pressure is avoided on the ridge portion 117 during diffusion bonding, and misalignment is suppressed, without affecting the radiation characteristics.

[0052] Next, we will explain the converter 140 between the waveguide slot subarray 100 and the input / output port 190 in the first embodiment. The converter 140 is a member that converts the transmission mode between the waveguide slot subarray 100, which is a ridged waveguide (ridge waveguide), and the input / output port 190, which is a ridgeless waveguide (waveguide).

[0053] 8A and 8B are diagrams illustrating the converter 140 according to the first embodiment. Fig. 8A is a perspective view of the waveguide slot subarray 100 with the wide wall 112 removed, and Fig. 8B is a perspective view of pattern B (thin plate member B) including the converter 140 portion. The directions in Figs. 8A and 8B 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 between the ridge portion 117 and the input / output port 190 and is connected to the ridge portion 117. The tapered portion 141 gradually widens in width from the ridge portion 117 in a tapered manner and contacts the narrow walls 143 and 144 just before the input / output port 190. The narrow wall 143 is made up of narrow walls 143a and 143b, and the narrow wall 144 is made up of narrow walls 144a and 144b. The narrow walls 143a and 144a are connected to the narrow walls 113 and 114, respectively. The distance between the narrow walls 143a and 144a gradually widens from the distance between the narrow walls 113 and 114. The distance W2 between narrow walls 143b and 144b, which are connected to narrow walls 143a and 144a, respectively, is constant. The distance W2 is wider than the distance W1 between narrow walls 113 and 114, which sandwich ridge portion 117. This is because the tube width (distance W2) of a waveguide without ridge portion 117 needs to be wider than the tube width (distance W1) of a waveguide with ridge portion 117. Narrow walls 143b and 144b are connected to end wall 116. If the width of tapered portion 141 and the distance between narrow walls 143a and 144a are changed in a curved manner, reflection can be easily suppressed.

[0055] The thickness of the tapered portion 141 is set to be the same as the thickness of the ridge portion 117. As a result, in the thin plate member B including the tapered portion 141, the end of the ridge portion 117 indicated by α is connected by the tapered portion 141 to the narrow wall 143 that is continuous with the narrow wall 113 and the narrow wall 144 that is continuous with the narrow wall 114, thereby suppressing misalignment during diffusion bonding.

[0056] 9A and 9B are diagrams illustrating the conversion characteristics of the converter 140. FIG. 9A is a perspective view of the converter 140, FIG. 9B is a perspective view of the converter 140 cut along the dashed line in FIG. 9A, and FIG. 9C is a reflection characteristic representing the conversion characteristics of the converter 140. The directions in FIGS. 9A and 9B are as shown. In FIG. 9C, the horizontal axis represents frequency [GHz], and the vertical axis represents S11 [dB] representing the reflection characteristics.

[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 of the converter 140 where the ridge portion 117 is provided (the ridge waveguide side) is designated as Port 1, and the side of the tapered portion 141 connected to the narrow walls 143 and 144 (the waveguide side) is designated as Port 2. Here, the reflection characteristics (S11 in the S parameters) for Port 1 were obtained by simulation.

[0058] 9(c), S11, which indicates the reflection characteristics, is extremely small, at -30 dB or less, in the frequency range from 56 GHz to 64 GHz. In other words, by passing through converter 140, radio waves can be transmitted from the ridge waveguide side to the waveguide side with little loss.

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

[0060] As shown in FIG. 10(a), Ports 1 to 8 were set in the waveguide slot array antenna 1. The RF signal exciting the waveguide slot subarray 100 was supplied from the waveguide through the converter 140 described above. The excitation conditions for each port were set to be the same, and the radiation characteristics of the waveguide slot array antenna 1 were obtained by simulation. The excitation conditions for each waveguide slot subarray 100 were set to be the same. In other words, the phase conditions of the RF signal supplied to each waveguide slot subarray 100 were set so that the main beam would be directed in the front direction (z direction), which is a direction perpendicular to the waveguide slot array antenna 1. Therefore, in the radiation pattern, the main beam is directed in the front direction (z direction), which is a direction perpendicular to the waveguide slot array antenna 1.

[0061] As shown in FIG. 10(b), S11, which indicates the reflection characteristics at Ports 1, 4, and 8, is almost the same in the frequency range from 56 GHz to 64 GHz, and has little frequency dependency.

[0062] Fig. 11 is a diagram illustrating the directivity when the main beam of the waveguide slot array antenna 1 according to the first embodiment is directed in the forward direction. Fig. 11(a) shows the directivity in the vertical plane, and Fig. 11(b) shows the directivity in the horizontal plane. 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 yz plane shown in Fig. 10(a), and the horizontal plane is the zx plane shown in Fig. 10(a). The +z direction is 0°. The main beam direction [°], half-width [°], and directional gain [dB] are also shown in a table.

[0063] The vertical and horizontal directivities shown in Figures 11(a) and 11(b) are almost the same at 58 GHz, 60 GHz, and 62 GHz, and have little frequency dependency. In addition, the main beam direction is 0°, and the half-width is narrow, at approximately 8° for the vertical directivity and approximately 10° for the horizontal directivity, and the difference with frequency is small. In other words, the waveguide slot array antenna 1 can be used in these frequency ranges.

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

[0065] The phase condition of the RF signal supplied to each waveguide slot subarray 100 is set (phase controlled) so that the main beam of the waveguide slot array antenna 1 is directed in the −26° direction in the horizontal plane. As shown in Figure 12(a), the direction of the main beam is approximately -26° and the half-width is approximately 11° at frequencies of 58 GHz, 60 GHz, and 62 GHz. There is little difference from the radiation characteristics when the main beam is directed forward, as shown in Figure 11. In other words, the waveguide slot array antenna 1 is an antenna capable of beamforming in the 60 GHz band. 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 method for manufacturing the waveguide slot array antenna 1 will be described. The waveguide slot array antenna 1 is constructed by stacking a waveguide slot array module 10, a radiating aperture module 20, and a beam forming module 30. As described above, these are fixed by a fixing mechanism 50. Therefore, as for the method for manufacturing the waveguide slot array antenna 1, it is sufficient to explain the method for manufacturing the waveguide slot array module 10.

[0067] As shown in FIG. 5(a), after designing the waveguide slot subarray 100, it is cut along a plane parallel to the wide wall 111 to create thin plate members corresponding to different patterns (patterns A, B, C, and D in FIG. 5) (a process for manufacturing a plurality of thin plate members). Then, as shown in FIG. 5(b), the required number of thin plate members of these patterns are stacked, pressurized, and heated at a temperature below the melting point of the thin plate members to perform diffusion bonding (a diffusion bonding process). In this way, 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 subarrays 100 are serially fed from the ends of the array. In this case, the beam direction of the waveguide slot subarrays 100 changes when the frequency is changed. However, in the waveguide slot array antenna 1, adjacent waveguide slot subarrays 100 are arranged in parallel in a staggered manner so that the input / output ports 190 to which power is fed are at the ends in the ±y direction. This cancels out the change in beam direction across the waveguide slot array antenna 1. However, grating lobes are more likely to occur when beamforming is performed.

[0069] Grating lobes will now be explained. In the waveguide slot array antenna 1 according to the first embodiment, when the phase condition is set so that the main beam is oriented in the -26° direction, beams Ga and Gb are generated that are separated in the ±y direction. The beams Ga and Gb are grating lobes. Two grating lobes appear separated in the y direction. When the beams Ga and Gb are indicated by distinguishing between frequencies, the numerical value of the frequency is added. When the design frequency is 60 GHz, the beam Ga at 58 GHz in FIG. 12(a) is 58 , Gb 58 and the size of the beam Ga at 62 GHz in Fig. 12(c). 62 , Gb 62 The magnitude of the beam Ga 60 , Gb 60 In this way, when beamforming is performed, grating lobes are likely to occur at frequencies other than the design frequency (here, 60 GHz).

[0070] To suppress the occurrence of grating lobes, it is effective to feed power from the center so as to divide the waveguide slot subarray 100 in half. If the waveguide slot subarray 100 is divided into two equal halves with the same number of radiating element sections 120, the position of the branch circuit that branches the feed in two directions (the position in the y direction in Figure 1(a)) will be the same between adjacent waveguide slot subarrays 100. If the branch circuit is composed of a waveguide, the pipe width of the waveguide constituting the branch circuit must be equal to or smaller than the pipe width of the waveguide slot subarray 100, which is a ridge waveguide. If the pipe width of the waveguide constituting the branch circuit exceeds the pipe width of the waveguide slot subarray 100, which is a ridge waveguide, mechanical interference will occur, making it impossible to place the branch circuit between adjacent waveguide slot subarrays 100. Furthermore, as mentioned above, reducing the pipe width of the waveguide constituting the branch circuit will impair the radio wave transmission characteristics.

[0071] Therefore, in the waveguide slot array antenna 2 in the second embodiment, the waveguide slot subarray 100 is divided into two parts with different numbers of radiating element sections 120. Figure 13 is a diagram illustrating a waveguide slot array antenna 2 according to the second embodiment. Figure 13(a) is a diagram illustrating the waveguide slot array module 10 and the power supply module 40 in the waveguide slot array antenna 2, Figure 13(b) is a perspective view of the waveguide slot array antenna 2, and Figure 13(c) is a cross-sectional view taken along line XIIIC-XIIIC in Figure 13(b). The directions in Figures 13(a), (b), and (c) are as shown.

[0072] Like 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 beam forming module 30. The waveguide slot array antenna 2 further includes a power feeding module 40. The beam forming module 30 is the same as that described in the first embodiment, and therefore will not be described below.

[0073] 13(b), the waveguide slot array antenna 2 is configured by stacking a power feed module 40, a waveguide slot array module 10, and a radiation aperture module 20 in this order in the z direction. A beam forming module 30 (not shown), the description of which will be omitted, is stacked on the -z direction side (back side) of the power feed module 40. The power feed 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 feed module 40 in order to show the relationship between the waveguide slot array module 10 and the feed module 40 in the waveguide slot array antenna 2. Fig. 13(a) shows the waveguide slot array module 10 seen through from the waveguide slot array module 10 side. Note that the ridge portion 117 is not shown.

[0075] The waveguide slot array antenna 2 includes eight waveguide slot subarrays 100, with the y direction as the longitudinal direction and the x direction as the transverse direction. Each waveguide slot subarray 100 includes nine radiating element sections 120 in the y direction. When distinguishing between the waveguide slot subarrays 100, they are designated by numbers, such as waveguide slot subarrays 100-1, 100-2, and 100-3. A feed waveguide 43 that feeds the waveguide slot subarrays 100 is provided in each waveguide slot subarray 100. When distinguishing between the feed waveguides 43, they are designated by numbers, such as feed waveguides 43-1, 43-2, and 43-3. The same applies to other cases. The waveguide slot subarray 100, which is a ridge waveguide, may be called the first line, and the feed waveguide 43 may be called the second line.

[0076] The number of radiating element sections 120 in the waveguide slot subarray 100 is nine. The radiating element sections 120 of the waveguide slot subarray 100-1 are divided into two halves, five on the -y direction side and four on the +y direction side. A branching circuit 150-1 is provided between the five radiating element sections 120 and four radiating element sections 120. The radiating element sections 120 of the waveguide slot subarray 100-2 adjacent to the waveguide slot subarray 100-1 are divided into two halves, four on the -y direction side and five on the +y direction side. A branching circuit 150-2 is provided between the four radiating element sections 120 and five radiating element sections 120. When the branching circuits 150-1 and 150-2 are not to be distinguished, they are referred to as branching circuits 150.

[0077] By arranging the waveguide slot subarrays 100, each having a different position of the radiating element section 120, in a staggered arrangement in parallel as described above, the branching circuits 150 are not at the same position in the y direction (do not overlap) between adjacent waveguide slot subarrays 100. If the feed waveguide 43, which is a feeding waveguide connected to the branching circuit 150, is extended along the longitudinal direction of the waveguide slot subarray 100 toward the side with fewer radiating element sections 120, the feed waveguide 43 will not be adjacent to the adjacent waveguide slot subarrays 100. This prevents the width of the feed waveguide 43 from being limited by the width of the waveguide slot subarray 100, which is a ridge waveguide. Note that if the radiating element sections 120 are divided into halves with different numbers, the branching circuit 150 will need to allocate power according to the number of radiating element sections 120 divided into two halves.

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

[0079] In the above, the number of radiating element sections 120 in the waveguide slot subarray 100 is set to an odd number, and the division is performed so that the difference is one. The number of radiating element sections 120 in the waveguide slot subarray 100 may be set to an even number, and the division may be performed so that the difference is two. The smaller the difference, the easier it is to allocate power. The number of radiating element sections 120 to be divided into two halves can be set according to the power allocation. To prevent the performance of the divided waveguide slot subarray 100 from being biased towards one of the halves, it is better that the numbers of the divided radiating element sections 120 are close to each other. It is preferable that the difference in the number of radiating element sections 120 is one.

[0080] 13(c), the feed module 40, the waveguide slot array module 10, and the radiating aperture module 20 are stacked in the z direction. The waveguide slot subarray 100 in the waveguide slot array module 10 includes a ridge portion 117, slots 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 feed module 40 is composed of two types of plate-like members 41 and 42. The feed waveguide 43 is composed of a groove (slit) provided in the plate-like member 42, a wide wall 111 constituting the waveguide slot subarray 100 as one wide wall (wide wall on the +z direction side), and the plate-like member 41 as the other wide wall (wide wall on the -z direction side). The feed waveguide 43 is a waveguide with a rectangular cross section. One end of the feed waveguide 43 extends to a feed opening 151 provided in the wide wall 111, and the other end of the feed waveguide 43 extends to the +y direction end of the waveguide slot subarray 100. An input / output port 190 is provided in the plate-like member 41 at the other end of the feed 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 inputs and outputs RF signals to and from the beam forming module 30 provided on the back side (-z direction side) of the power feeding module 40. Therefore, the same reference numerals are used.

[0082] The waveguide slot array module 10 and the feed module 40 are stacked on top of each other. That is, the waveguide slot subarray 100 in the waveguide slot array module 10 and the feed waveguide 43 in the feed module 40 are provided back to back.

[0083] Considering that the power supply module 40 is formed by diffusion bonding, the fewer the types of fabrication plates (pattern types) that make up the thin plate members, the better. As shown in Figure 13(c), by configuring the feed waveguide 43 and the input / output port 190 in an L-shape, the number of fabrication plate types can be limited to two: a groove pattern in the plate-shaped member 42 that becomes the feed waveguide 43, and a pattern in the plate-shaped member 41 that becomes the wide wall on the -z direction side of the feed waveguide 43 and includes the input / output port 190.

[0084] Next, we will explain the configuration of the branching circuit 150 that branches the waveguide slot subarray 100 into two. Here, we will assume that the waveguide slot subarray 100 shown in Figure 13(a) has nine radiating element sections 120 and is divided into two groups of four and five.

[0085] Fig. 14 is a diagram illustrating the configuration of a branching circuit 150A in the waveguide slot subarray 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) do not show the wide wall 112 in which the slots 121 of the waveguide slot subarray 100 are provided. The directions in Figs. 14(a) and (b) are as shown.

[0086] As shown in FIG. 14(a), the branch circuit 150A is composed of Structure I and Structure II sandwiching a feed opening 151. In the waveguide slot subarray 100, Structure I is the side with a larger number of radiating element portions 120, and Structure II is the side with a smaller number of radiating element portions 120. The ridge portion 117 is divided by the feed opening 151. The ridge portion 117 on the Structure I side is referred to as ridge portion 117a, and the ridge portion 117 on the Structure II side is referred to as ridge portion 117b.

[0087] In structure I, the ridge portion 117a extends up to the feed aperture 151. In structure I, a matching element 153 is provided on the narrow wall 113 at the end of the feed aperture 151, and a matching element 154 is provided on the narrow wall 114. The matching elements 153 and 154 may contact the feed aperture 151, or a gap may be provided between them. The matching elements 153 and 154 are similar to the matching element 131, which is 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 wall 111 and the wide wall 112 (see FIG. 3(b)). The matching element 154 is provided on the narrow wall 114 so as to connect the wide wall 111 and the wide wall 112.

[0088] In structure II, a gap is provided between the ridge portion 117b and the feed opening 151. The gap may be referred to as an offset P. In structure II, no matching elements such as the matching elements 153 and 154 are provided. As described above, the feed waveguide 43 extends to the side with fewer radiating element portions 120, that is, to the structure II side (see FIG. 13(a)).

[0089] Fig. 15 is a diagram illustrating 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 between the waveguide slot subarray 100 and the branch circuit 150A (see Fig. 14(a)). The directions in Figs. 15(a) and (b) are as shown.

[0090] The feed waveguide 43 in the feed module 40 includes a waveguide section 43a and a matching section 43b. As shown in Fig. 15(a), the matching section 43b faces the feed opening 151 in the branching circuit 150A of the waveguide slot subarray 100. The pipe width W4 of the matching section 43b is wider than the pipe width W3 of the waveguide section 43a. This is to match the feed waveguide 43 (waveguide section 43a), which is a waveguide, with the waveguide slot subarray 100, which is a ridge waveguide. The branch circuit 150A of the waveguide slot subarray 100 and the matching section 43b of the feed waveguide 43 combine to form the branch circuit 150, which has the function of converting from a waveguide to a ridge waveguide and the function of converting from a ridge waveguide to a waveguide.

[0091] As described above, when a waveguide slot subarray 100 having nine radiating element portions 120 is divided into two groups, one with five radiating element portions 120 and the other with four radiating element portions 120, a power distribution ratio of 5:4 is required. In other words, the power supplied to the five radiating element portions 120 side is 1.25 times the power supplied to the four radiating element portions 120 side. Here, the conversion characteristics were simulated when the power distribution ratio was 3:2. This is because, in order to keep side lobes low, it is best to set the power distribution ratio to be equal to or greater than the ratio of the numbers of radiating element portions 120. When the power distribution ratio is 3:2, the power supplied to the five radiating element portions 120 side is 1.5 times the power supplied to the four radiating element portions 120 side.

[0092] Figure 16 is a diagram illustrating the configuration of a branch circuit 150 used to evaluate branching characteristics. Figure 16(a) is a perspective view of the branch circuit 150, Figure 16(b) is a perspective view of the branch circuit cut along the dashed line in Figure 16(a), and Figures 16(c), (d), and (e) are plan views of branch circuits A with different configurations used to evaluate branching characteristics. The directions in Figures 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 section 43b of the feed waveguide 43 in the feed module 40 shown in FIG. 15. FIG. 16(a) shows the branch circuit 150 viewed from the structure I side shown in FIG. 14(a). As shown in FIG. 16(b), in the cross section taken along the dashed line in FIG. 16(a), on the structure I side, a ridge portion 117a is provided up to the feed opening 151. On the structure I side, a matching element 153 is provided adjacent to the feed opening 151. On the other hand, on the structure II side, the ridge portion 117b is provided at an offset P from the feed opening 151. As shown in FIG. 16(b), the structure I side is designated Port 2, the structure II side is designated Port 3, and the feed waveguide 43 side is designated Port 1.

[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 referred to 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 of the feed opening 151. This is referred to as Model E. Fig. 16(e) shows a configuration in which the matching elements 153 and 154 are removed from model A in Fig. 16(c). This is referred to 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 17(b), the horizontal axis represents frequency [GHz]. The vertical axis of FIG. 17(a) represents the power distribution ratio, which is the square of the ratio between the passage parameter S21 from Port1 to Port2 and the passage parameter S31 from Port1 to Port3 (|S21 / S31| 2 ) The vertical axis of FIG. 17(b) is S11 [dB], which indicates the reflection characteristic at Port 1.

[0096] As shown in FIG. 17(a), Model D has a power distribution ratio of 1.5, which matches the set value. Model D has small frequency dependency in the frequency range from 56 GHz to 64 GHz. On the other hand, Model E has a power distribution ratio of 1, and different powers cannot be supplied to Port 2 and Port 3. However, Model E has small frequency dependency in the above frequency range. Model F has a power distribution ratio in the range from 1.3 to 1.8, but has large frequency dependency in the above frequency range.

[0097] The results of Models D and E show that the power distribution ratio can be adjusted by providing an offset P between the ridge portion 117 and the feed aperture 151. The results of Models D and E also show that the power distribution ratio can be adjusted and the frequency characteristics can be improved by providing matching elements 153 and 154, which are so-called irises.

[0098] 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 according to the second embodiment. The ridge portion 117 is divided into ridge portions 117a and 117b.

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

[0100] Ports 1 to 8 were set as shown in Figure 19(a). The RF signal exciting the waveguide slot subarray 100 was supplied from the power supply module 40 through the branch circuit 150 described above. The excitation conditions for each port were set to be the same, and the radiation characteristics of the waveguide slot array antenna 1 were obtained by simulation. The excitation conditions for each waveguide slot subarray 100 were set to be the same. In other words, the phase conditions of the RF signal supplied to each waveguide slot subarray 100 were set so that the main beam would be directed in the front direction (z direction), which is a direction perpendicular to the waveguide slot array antenna 1. Therefore, in the radiation pattern, the main beam is directed in the front direction (z direction), which is a direction perpendicular to the waveguide slot array antenna 1.

[0101] As shown in FIG. 19(b), S11, which indicates the reflection characteristics at Ports 1, 4, and 8, is −10 dB or less in the frequency range from 56 GHz to 64 GHz.

[0102] Fig. 20 is a diagram illustrating the directivity when the main beam of the waveguide slot array antenna 2 according to the second embodiment is directed in the forward direction. Fig. 20(a) shows the directivity in the vertical plane, and Fig. 20(b) shows the directivity in the horizontal plane. In the graphs of Fig. 20(a) and (b), the horizontal axis represents the angle [°] and the vertical axis represents the relative gain [dB]. The main beam direction [°], half-width [°], and directional gain [dB] are also shown in a table.

[0103] The vertical and horizontal directivities shown in Figures 20(a) and (b) are almost the same at 58 GHz, 60 GHz, and 62 GHz, and have little frequency dependency. In addition, the main beam direction is 0°, and the half-width is narrow, at about 9° for the vertical directivity and about 10° for the horizontal directivity, and the difference with frequency is small. In other words, the waveguide slot array antenna 2 has characteristics similar to 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 in the horizontal plane at an angle of -26° from the front direction by phase control of each waveguide slot subarray 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 shows the angle [°] and the vertical axis shows the relative gain [dB].

[0105] The phase condition of the RF signal supplied to each waveguide slot subarray 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 main beam direction is approximately −26° and the half-width is approximately 11° at frequencies of 58 GHz, 60 GHz, and 62 GHz. This shows little difference from the radiation characteristics when the main beam is directed forward, as shown in FIG. 20. In other words, the waveguide slot array antenna 2 is capable of beamforming in the 60 GHz band. The waveguide slot array antenna 2 to which the second embodiment is applied can be manufactured with high precision by diffusion bonding. Furthermore, as shown in FIGS. 21(a), (b), and (c), the grating lobes are suppressed even at frequencies other than the design frequency, compared to the waveguide slot array antenna 1 of the first embodiment. In other words, the waveguide slot array antenna 2 of the second embodiment has a wider bandwidth than the waveguide slot array antenna 1 of the first embodiment.

[0106] The waveguide slot array antenna 2 in the second embodiment is thicker than the waveguide slot array antenna 1 in the first embodiment by the thickness of the power supply module 40, but is a thin antenna configured in a flat plate shape that allows control of 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 of the above-described embodiments. It is clear from the claims that various modifications and improvements to the above-described embodiments are also included in the technical scope of the present invention. Furthermore, various modifications may be made as long as they do not deviate from the spirit of the present invention. [Explanation of symbols]

[0108] 1, 2... Waveguide slot array antenna, 10... Waveguide slot array module, 20... Radiating aperture module, 30... Beam forming module, 32... Beam forming circuit, 40... Feed module, 43... Feed waveguide, 50... Fixing mechanism, 100, 100'... Waveguide slot subarray, 117, 117a, 117b... Ridge portion, 120... Radiating element portion, 121... Slot, 131, 153, 154... Matching element, 132... First matching element, 133... Second matching element, 140... Converter, 141... Tapered portion, 150, 150-1, 150-2, 150A, 150B... Branch circuit, 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, surrounded by two wide walls facing each other and two narrow walls connecting the two wide walls and having a width narrower than the wide walls, a plurality of slots in one of the wide 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 the two wide walls or to connect the first matching element and a wide wall opposite 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 on the wide wall on which the ridge section is provided and gradually widening in width from the ridge section, and two narrow walls connected to the tapered section and spaced apart gradually from the space between the narrow walls.

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 to the slots from input / output ports provided at the ends, and are arranged in parallel so that the input / output ports are positioned alternately in the longitudinal direction of the waveguide slot subarrays in the direction of adjacent waveguide slot subarrays.

5. 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 plurality of thin plate members at a temperature equal to or lower than the melting point of the thin plate members while applying pressure to the plurality of thin plate members, thereby diffusion bonding the plurality of thin plate members; A method for manufacturing a waveguide slot array antenna, comprising:

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