Slot array antenna

Abstract

To provide a slot array antenna which can be manufactured by using a diffusion junction method while maintaining a reflection suppression function.SOLUTION: A slot array antenna 10 comprises: a radiator 14 that includes radiation slots 72 and 74 on a narrowing wall 62a on a ceiling side of a rectangular waveguide 62; and a power supply body 12 in which a power supply pipe 32 is formed. The power supply body 12 comprises: a top plate that constructs a top surface 32e of the power supply pipe 32, and in which a power supply port 52 connecting the rectangular waveguide 62 with the power supply pipe 32 is formed; a power supply base body in which a notch of which a width is expanded toward a depth wall 32d from an open 32a while constructing the side wall and the depth wall 32d of the power supply pipe 32 is formed; and a bottom plate constructing a bottom surface 32f of the power supply pipe 32. The power supply base body is a lamination body of a plurality of thin plates 40. One thin plate that is not overlapped each other comprises coupling plates 36A-36C and 38A-38B connecting the side wall on both sides. Both of the coupling plates 36A-36C and 38A-38B construct reflection suppression walls 36 and 38.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present disclosure relates to a slot array antenna for use in high frequency bands of millimeter waves or higher. [Background technology]

[0002] Non-Patent Document 1 discloses a hollow waveguide slot array antenna for a 150 GHz band channel sounder. Hereinafter, the antenna disclosed in Non-Patent Document 1 is referred to as the conventional antenna. The conventional antenna has a radial line in the center, and the inside is divided into 16 parts in the circumferential direction. A feed opening is provided on the underside of the conventional antenna, and the radial line is short-circuited at the end of the feed opening. 64 slot arrays on the narrow wall of a rectangular waveguide are arranged around the radial line. One rectangular waveguide has 16 slots arranged at an angle alternately at intervals of 1 / 2 the guide wavelength. A dielectric cylinder with a grid provided on the inside is installed on the outside of the rectangular waveguide array.

[0003] In the conventional antenna, radio waves enter the radial line from one feed aperture through the bend created by the H-plane bend, and are propagated to the four rectangular waveguide narrow wall slot arrays by the H-plane T-junction structure. In order to suppress the reflection of radio waves at the bend, a reflection suppression wall is provided at the bend. In addition, a reflection suppression plate is inserted into the H-plane T-junction to suppress the reflection at the slot. [Prior art documents] [Non-patent literature]

[0004] [Non-Patent Document 1] Rikako Yamaguchi, Jiro Hirokawa, Takashi Tomura (Tokyo Institute of Technology), Minoru Inomata, Wataru Yamada (NTT), “Feed Design of Hollow Waveguide Slot Array Antenna for 150GHz Band Channel Sounder,” IEICE Society Conference, September 2022 Summary of the Invention [Problem to be solved by the invention]

[0005] To perform accurate beamforming using a slot array antenna, it is necessary to reduce the occurrence of grating lobes by spacing the antenna elements close to λ / 2. When array antennas are used in high frequency bands above millimeter waves, particularly in the terahertz waveband, the wavelength of the terahertz waveband is very short, so the thickness of the waveguide must be thin in order to place the antenna elements close to each other. A suitable method for reducing the thickness of the waveguide is the diffusion bonding method (laminated thin plate diffusion bonding method).

[0006] In order to apply the diffusion bonding method to the manufacture of a slot array antenna, mechanical pressure must be applied to the slot array antenna, but with the structure of the conventional antenna, it is not possible to apply mechanical pressure to the reflection suppression wall or plate, making it difficult to apply the diffusion bonding method to the manufacture.

[0007] The present disclosure has been made in view of the above-mentioned problems, and has an object to provide a slot array antenna that can be manufactured by using a diffusion bonding method while maintaining a reflection suppressing function. [Means for solving the problem]

[0008] One aspect of the present disclosure includes a slot array antenna for use in millimeter-wave or higher-frequency bands. The slot array antenna includes a radiator in which a plurality of rectangular waveguides, each of which is closed at both ends, are formed in parallel. The slot array antenna also includes a feeder in which a feed tube having a rectangular cross-sectional shape is formed and connected to each of the rectangular waveguides.

[0009] The radiator includes a slot plate, a radiation base body, and a bottom plate. The slot plate forms a narrow wall on the ceiling side of each of the rectangular waveguides, and a plurality of radiation slots are formed at predetermined intervals on the narrow wall. The radiation base body has a plurality of holes that form the wide wall and end wall of each of the rectangular waveguides. The bottom plate forms the narrow wall on the bottom side of each of the rectangular waveguides. The bottom plate has a feed port that opens in the center of each of the rectangular waveguides and connects each of the rectangular waveguides to a feed tube.

[0010] The feeder includes a top plate, a feed base body, and a bottom plate. The top plate forms the top surface of the feed tube, and a feed port is formed on the top surface to connect each of the multiple rectangular waveguides to the feed tube. The top plate of the feeder may also serve as the bottom plate of the radiator. The feed base body has a notch that forms the side wall and the back wall of the feed tube. The open portion of the notch forms the entrance of the feed tube. The bottom plate forms the bottom surface of the feed tube.

[0011] The power supply base body is a laminate of multiple thin plates. Some of the multiple thin plates that do not overlap each other, except for the top and bottom thin plates, are provided with connecting plates that connect the side walls on both sides. The reflection suppressing walls are formed by the connecting plates provided on some of the multiple thin plates.

[0012] In the above slot array antenna, the bottom plate may be composed of a cutoff waveguide body and a cutoff waveguide body. A plurality of cutoff waveguides, both ends of which are closed, are formed in parallel in the cutoff waveguide body. The reflection-suppressing slot plate is a plate in which a plurality of reflection-suppressing slots are formed corresponding to the plurality of cutoff waveguides, and constitutes the top surface of the plurality of cutoff waveguides and the bottom surface of the plurality of rectangular waveguides. The plurality of cutoff waveguides and the plurality of rectangular waveguides are connected via at least one reflection-suppressing slot. This enables excitation with a traveling wave. Effect of the Invention

[0013] According to the slot array antenna configured as described above, mechanical pressure can be applied between the members that configure the slot array antenna. Although pressure is not applied to the connecting plates that configure the reflection suppression wall, there is a gap between the connecting plates, so that the connecting plates do not hinder the compression of the thin plates by mechanical pressure. In addition, since the interval between the connecting plates that configure the reflection suppression wall is narrower than the wavelength in the guide and the polarized waves are parallel to the connecting plates, it is possible to obtain reflection suppression characteristics equivalent to those of a continuous reflection suppression wall. Therefore, by configuring the slot array antenna as described above, it is possible to manufacture the antenna using a diffusion bonding method while maintaining the reflection suppression function. [Brief description of the drawings]

[0014] [Figure 1] 1 is a longitudinal sectional view of a slot array antenna according to a first embodiment of the present disclosure. FIG. [Diagram 2] 2 is a view taken along the arrow AA of the slot array antenna shown in FIG. 1. [Diagram 3] 2 is a view of the slot array antenna shown in FIG. 1 taken along the arrow BB. [Figure 4] 2 is a view of the slot array antenna shown in FIG. 1 taken along the arrow CC. [Diagram 5] FIG. 2 is a view of the slot array antenna shown in FIG. 1 taken along the arrow DD. [Figure 6] FIG. 2 is a view taken along an arrow EE of the slot array antenna shown in FIG. [Figure 7] FIG. 2 is an exploded perspective view of the slot array antenna shown in FIG. [Figure 8] FIG. 2 is a vertical sectional view of a modified example of the slot array antenna shown in FIG. [Figure 9] 9 is a view of the slot array antenna shown in FIG. 8 taken along the arrow BB. [Figure 10] 13A to 13C are diagrams showing an example of the shape of a reflection suppressing slot provided in a radiator in the second embodiment of the present disclosure. [Figure 11] 13A and 13B are diagrams showing other examples of the shape of the reflection-suppressing slot provided in the radiator in the second embodiment of the present disclosure. [Figure 12]FIG. 11 is a longitudinal sectional view of a slot array antenna according to a second embodiment of the present disclosure. [Figure 13] 13 is a view of the slot array antenna shown in FIG. 12 taken along the arrow BB. [Figure 14] FIG. 13 is an exploded perspective view of the slot array antenna shown in FIG. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0015] 1. First embodiment A slot array antenna according to a first embodiment of the present disclosure will be described below with reference to the drawings. The slot array antenna according to the present embodiment is suitable for use in high frequency bands equal to or higher than millimeter waves, particularly in the terahertz wave band.

[0016] FIG. 1 shows a vertical cross section of a slot array antenna 10 according to this embodiment. The slot array antenna 10 includes a feeder 12 that feeds signal power, and a radiator 14 that radiates radio waves using the signal power fed from the feeder 12. The feeder 12 and the radiator 14 are made of, for example, metal. The top-bottom direction when the slot array antenna 10 is actually installed is the z-axis direction in FIG. 1. On the other hand, the top-bottom direction when the components constituting the slot array antenna 10 are stacked and pressurized is the y-axis direction in FIG. 1. In this specification, the components are named with the positive direction of the y-axis representing the ceiling direction and the negative direction representing the bottom direction.

[0017] The radiator 14 is formed with a rectangular waveguide 62 closed at both ends by end walls 62e, 62f. A plurality of radiation slots 72, 74 are formed at a predetermined interval in a narrow wall 62a on the ceiling side of the rectangular waveguide 62. Specifically, the interval between adjacent radiation slots 72, 74 is set to 1 / 2 the guide wavelength of the radio wave. In addition, 16 radiation slots 72, 74 are formed in one rectangular waveguide 62. The radiation slots 72 and radiation slots 74 have shapes that are mirror images of each other, as will be described in detail later.

[0018] A feed port 52 for receiving signal power from the feeder 12 is provided in the narrow wall 62b on the bottom side of the rectangular waveguide 62. The feed port 52 has a size approximately equal to the distance between adjacent radiation slots 72, 74. The feed port 52 is provided in the center of the rectangular waveguide 62. In other words, the slot array antenna 10 employs a central feed structure. Because of the fine processing, it is not necessary to install a reflection suppression plate, as in conventional antennas, on the narrow wall 62a on the ceiling side of the rectangular waveguide 62. The vibration mode in the rectangular waveguide 62 is a standing wave excitation.

[0019] The power feeder 12 is formed with a feed tube 32 connected to a rectangular waveguide 62. The feed tube 32 extends in the same direction as the longitudinal direction of the rectangular waveguide 62 from a feed opening 32a formed on an end face of the power feeder 12, reaching the rear wall 32d. A feed port 52 opens on a top face 32e of the feed tube 32 at a position slightly away from the rear wall 32d. The feed tube 32 and the rectangular waveguide 62 are connected by the feed port 52.

[0020] The feed tube 32 has a rectangular cross-sectional shape. However, the cross-sectional shape is not constant. The feed tube 32 is divided into a front section 32F where the distance between the side walls increases continuously from the feed opening 32a toward the back wall 32d, and a rear section 32R located behind the front section 32F and where the distance between the side walls is constant. The feed port 52 is provided in the rear section 32R. The feed body 12 includes a laminate of multiple thin plates 40, which will be described in detail later. The back wall 32d and side walls of the feed tube 32 are composed of a laminate of thin plates 40. The thin plates 40 have a thin thickness of about a fraction to a few tenths of the wavelength in the tube.

[0021] Two reflection suppression walls 36, 38 are provided inside the feed tube 32. The first reflection suppression wall 38 is provided on the rear wall 32d side of the feed port 52, in a corner formed by the bottom surface 32f and the rear wall 32d of the feed tube 32. The second reflection suppression wall 36 is provided to stand from the bottom surface 32f relative to the feed port 52.

[0022] The first reflection suppressing wall 38 is composed of a plurality of connecting plates, for example, two connecting plates 38A and 38B, connecting both side walls of the feed tube 32. Of the two connecting plates 38A and 38B, the connecting plate 38B, which is farther from the bottom surface 32f, has a shorter protruding distance from the back wall 32d to the edge of the opening 32a side than the connecting plate 38A, which is closer to the bottom surface 32f. Therefore, the first reflection suppressing wall 38 has a stepped appearance. The connecting plates 38A and 38B constituting the first reflection suppressing wall 38 are parts of two thin plates 40 that do not overlap each other. A gap of one thin plate is provided between the connecting plates 38A and 38B. In addition, the thin plate 40 on which the lowest connecting plate 38A is formed is not overlapped on the bottom surface 32f. A gap of at least one thin plate is provided between the connecting plate 38A and the bottom surface 32f.

[0023] The second reflection suppression wall 36 is composed of a plurality of connecting plates, for example, three connecting plates 36A, 36B, and 36C, which connect the side walls on both sides of the feed tube 32. The three connecting plates 36A, 36B, and 36C have substantially the same plate shape and are provided at the same position on the bottom surface 32f. Therefore, the second reflection suppression wall 36 has an appearance of a partition wall. The connecting plates 36A, 36B, and 36C constituting the second reflection suppression wall 36 are parts of three thin plates 40 that do not overlap each other. A gap of one thin plate is provided between the connecting plates 36A, 36B, and 36C. In addition, the thin plate 40 on which the lowest connecting plate 36A is formed is not overlapped on the bottom surface 32f. A gap of at least one thin plate is provided between the connecting plate 36A and the bottom surface 32f.

[0024] A radome 80 is disposed at a certain distance from the surface of the slot array antenna 10 on which the radiation slots 72, 74 are provided. A grid 82 is provided inside the radome 80. The grid 82 suppresses cross-polarized waves generated in directions other than the front direction of the slot array antenna 10. In this embodiment, the radome 80 is not included in the components that constitute the slot array antenna 10, but the radome 80 may be included in the components that constitute the slot array antenna 10.

[0025] Next, the configuration of the slot array antenna 10 will be described in more detail with reference to the planes of the arrows AA, BB, CC, DD, and EE of the slot array antenna 10 shown in FIG.

[0026] FIG. 2 is a view taken along the line AA of the slot array antenna 10 shown in FIG. 1. The line AA is a cross section of the feed base body 30 constituting the feed body 12. The feed base body 30 is stacked on the bottom plate 20 constituting the bottom surface 32f of the feed tube 32. The feed base body 30 is formed with cutouts constituting the side walls 32b, 32c and the inner wall 32d of the feed tube 32. The cutouts correspond to the feed opening 32a, which is the entrance of the feed tube 32. The feed base body 30 is a laminate of the aforementioned thin plates 40. Therefore, the cutouts constituting the feed tube 32 are formed for each thin plate 40. However, for some of the thin plates 40, connecting plates constituting the aforementioned reflection suppression walls 36, 38 are formed. As can be seen from the vertical cross section of FIG. 1, the connecting plates 36C, 38A, and 38B shown in FIG. 2 are each a part of a separate thin plate 40.

[0027] Fig. 3 is a view taken along the line BB of the slot array antenna 10 shown in Fig. 1. The line BB is the surface of a top plate 50 which constitutes the top surface of the feed tube 32. The top plate 50 is stacked on the feed base body 30 described above. The top plate 50 also serves as the bottom plate of the radiator 14. However, a top plate for the feeder 12 may be provided separately from the bottom plate of the radiator 14. A rectangular feed port 52 is formed in the top plate 50.

[0028] FIG. 4 is a view taken along the CC arrow of the slot array antenna 10 shown in FIG. 1. The CC arrow plane is a cross section of the radiating base body 60 constituting the radiator 14. The radiating base body 60 is stacked on the top plate 50. The top plate 50 also serves as a bottom plate constituting the narrow wall 62b on the bottom side of the rectangular waveguide 62. The radiating base body 60 has four rectangular holes formed in parallel. Each rectangular hole constitutes the wide walls 62c, 62d and the end walls 62e, 62f of the rectangular waveguide 62. The power feed port 52 formed on the top plate (bottom plate of the radiator 14) 50 opens at the center of each of the four rectangular waveguides 62. With this configuration, the signal power introduced from the power feed opening 32a to the power feed tube 32 is propagated from the power feed port 52 into the four rectangular waveguides 62. The radiating base body 60 may be a laminate of a plurality of thin plates.

[0029] Fig. 5 is a view taken along the arrow DD of the slot array antenna 10 shown in Fig. 1. The plane taken along the arrow DD is the surface of a slot plate 70 which constitutes the narrow wall on the ceiling side of the rectangular waveguide 62. Four rows of radiation slots 72, 74 are formed in the slot plate 70 in accordance with the positions of the four rectangular waveguides 62. The radiation slots 72 and the radiation slots 74 are arranged alternately in each row.

[0030] The radial slots 72 are asymmetric I-shaped slots. As shown in the enlarged view, the radial slots 72 are composed of left and right vertical slots 72b, 72c extending in the length direction of the narrow wall, and a horizontal slot 72a extending in the width direction of the narrow wall and connecting the left and right vertical slots 72b, 72c. In the drawing, the vertical slot 72b on the left side is connected to the horizontal slot 72a below the center, and the vertical slot 72c on the right side is connected to the horizontal slot 72a above the center.

[0031] The radial slots 74 are also asymmetric I-shaped slots. The radial slots 74 are composed of left and right vertical slots 74b, 74c that extend in the length direction of the narrow wall, and a horizontal slot 74a that extends in the width direction of the narrow wall and connects the left and right vertical slots 74b, 74c. The radial slots 74 are in a mirror image relationship with the radial slots 72. In the figure, the vertical slot 74b on the left side is connected to the horizontal slot 74a above the center, and the vertical slot 74c on the right side is connected to the horizontal slot 74a below the center.

[0032] Fig. 6 is a view taken along the arrow EE of the slot array antenna 10 shown in Fig. 1. The plane taken along the arrow EE is the front surface of a radome 80. On the rear surface of the radome 80, a plurality of rows of grids 82 are formed.

[0033] FIG. 7 is an exploded perspective view showing the slot array antenna 10. As shown in this exploded perspective view, the slot array antenna 10 is composed of a feeder 12 and a radiator 14. The feeder 12 is composed of a bottom plate 20, a feed base body 30 constituting a feed tube 32, and a top plate 50 on which a feed port 52 is formed, which are laminated together. The feed base body 30 is a laminate of a plurality of thin plates 40. The shapes of the thin plates 40 are all the same except for those on which the connecting plates 36A, 36B, 36C, 38A, and 38B are formed. The radiator 14 is composed of a bottom plate 50 which also serves as the top plate of the feeder 12, a radiation base body 60 constituting a rectangular waveguide 62, and a slot plate 70 on which radiation slots 72 and 74 are formed, which are laminated together. At a position at a predetermined distance from the front surface of the slot plate 70, a radome 80 on which a number of grids 82 are formed on the rear surface is disposed.

[0034] According to the slot array antenna 10 configured as described above, the components 20, 30, 50, 60, 70 constituting the slot array antenna 10 can be laminated and then mechanically pressured in this state to be bonded by diffusion bonding. In the conventional antenna, the reflection suppression walls in the feed tube also prevent the use of the diffusion bonding method, but in the slot array antenna 10, the reflection suppression walls 36, 38 are configured as connecting plates with gaps, so that the feed base body 30, which is a laminate of thin plates 40, can be mechanically pressurized.

[0035] The connecting plates 36A, 36B, and 36C that constitute the first reflection suppressing wall 38 are each part of a separate thin plate 40, but they do not overlap each other, so that there are gaps between the connecting plates 36A, 36B, and 36C. Therefore, when the stack of thin plates 40 is compressed by mechanical pressure, no pressure is applied to the connecting plates 36A, 36B, and 36C, but the connecting plates 36A, 36B, and 36C do not hinder the compression of the thin plates 40. The same is true for the connecting plates 38A and 38B that constitute the second reflection suppressing wall 36, and because there is a gap between the connecting plates 38A and 38B, the connecting plates 38A and 38B do not hinder the compression of the thin plates 40.

[0036] By making it possible to manufacture the slot array antenna 10 using the diffusion bonding method, the thickness of the waveguide of the slot array antenna 10 can be reduced. As a result, the beamforming performance can be improved in the high frequency band of millimeter waves or higher, particularly in the terahertz wave band. In addition, since the radiation slots 72 and 74 are asymmetric I-shaped slots, the amount of coupling between the antenna elements is weakened, and the beamforming performance can be further improved.

[0037] Furthermore, in the slot array antenna 10 configured as above, the gap between the connecting plates that configure the reflection suppression walls 36, 38 is sufficiently narrow compared to the wavelength in the guide, and the polarization is parallel to the connecting plates, so that no radio waves enter the gap. Therefore, the reflection suppression walls 36, 38 can obtain reflection suppression characteristics equivalent to those of the continuous reflection suppression walls of conventional antennas. Therefore, by configuring the slot array antenna 10 as above, it is possible to maintain the reflection suppression function while enabling manufacturing using the diffusion bonding method.

[0038] 8 and 9 show the configuration of a modified example of the slot array antenna 10. Fig. 8 is a vertical cross-sectional view of the modified example of the slot array antenna 10, and Fig. 9 is a view of the slot array antenna 10 shown in Fig. 8 as viewed from the arrow BB. As shown in Fig. 8 and 9, in the modified example, the boundary between the front portion 32F and the rear portion 32R of the feed tube 32 is shifted toward the feed opening 32a, and a first reflection suppression wall 38 composed of connecting plates 36A, 36B, and 36C is provided in the rear portion 32R. No matter where the first reflection suppression wall 38 is provided, it does not affect the application of the diffusion bonding method, so the first reflection suppression wall 38 may be provided at a position where a desired reflection suppression characteristic is obtained.

[0039] 2. Second embodiment In the structure of the slot array antenna 10 of the first embodiment, when a beam is radiated in the forward direction, the radiating slots 72, 74 are excited by a standing wave. However, in the case of standing wave excitation, the operating band becomes narrower as the number of the radiating slots 72, 74 increases. In order to widen the operating band, it is effective to enable excitation by a traveling wave by providing a reflection suppressing structure that suppresses reflection by the radiating slots 72, 74 in the rectangular waveguide 62 as the radiating waveguide. However, since the wavelength of a high frequency such as the 150 GHz band is short, it is difficult to extend a wall that suppresses reflection from the wall surface of the rectangular waveguide 62 in the structure of the slot array antenna 10 of the first embodiment.

[0040] Therefore, in the second embodiment of the present disclosure, a cutoff waveguide is provided in the radiator, and a reflection suppressing slot is formed between the cutoff waveguide and a rectangular waveguide to configure a reflection suppressing structure. Specifically, as shown in Fig. 10 and Fig. 11, a cutoff waveguide 54 is provided at the bottom of a rectangular waveguide 62, and a reflection suppressing slot 58 is formed in a plate (reflection suppressing slot plate) 56 that separates the rectangular waveguide 62 and the cutoff waveguide 54. Reflection can be suppressed by making the amplitudes of the reflected wave by the radiating slot and the reflected wave by the reflection suppressing slot 58 equal and in opposite phase.

[0041] The shape of the reflection-suppressing slot 58 illustrated in FIG. 10 is rectangular. It has been confirmed through experiments that the reflection amount changes continuously by continuously changing the length of the reflection-suppressing slot 58 in the length direction of the cutoff waveguide 54 (hereinafter, referred to as the slot length). In order to freely realize a desired directivity in a slot array antenna, it is necessary to freely and continuously change the radiation amount from each radiation slot, and accordingly, it is necessary to freely and continuously change the reflection amount by the reflection suppressing structure. According to the configuration shown in FIG. 10, a plurality of reflection-suppressing slots 58 can be formed in the reflection-suppressing slot plate 56, and each slot length can be made different. By providing a plurality of reflection-suppressing slots 58 each having a different slot length, the reflection amount can be freely and continuously changed. Note that, since the electromagnetic field is concentrated around the reflection-suppressing slot 58 in the cutoff waveguide 54, it is not necessary to provide a wall between the reflection-suppressing slots 58 in the cutoff waveguide 54.

[0042] The reflection suppressing slot 58 illustrated in Fig. 11 is H-shaped. The H-shaped reflection suppressing slot 58 has the advantage that the slot length can be made shorter while ensuring the amount of reflection, compared to the rectangular reflection suppressing slot 58. In the slot array antenna of this embodiment described below, an H-shaped reflection suppressing slot 58 is provided.

[0043] Fig. 12 shows a vertical cross section of a slot array antenna 11 according to this embodiment. The slot array antenna 11 includes a feeder 12 that feeds signal power, and a radiator 15 that radiates radio waves using the signal power fed from the feeder 12. The configuration of the feeder 12 is the same as that of the slot array antenna 10 according to the first embodiment. The slot array antenna 11 according to this embodiment is different from the slot array antenna 10 according to the first embodiment in the configuration of the radiator 15. In Fig. 12 and subsequent drawings, components common to the slot array antenna 10 according to the first embodiment are denoted by the same reference numerals, and duplicated explanations thereof will be omitted.

[0044] The radiator 15 is formed with a cutoff waveguide 54, both ends of which are closed by end walls 54e, 54f. The cutoff waveguides 54 are provided above and below the feed port 52. The narrow wall 54b on the bottom side of the cutoff waveguide 54 is in a back-and-forth relationship with the top surface 32e of the feed tube 32, and the narrow wall 54a on the ceiling side of the cutoff waveguide 54 is in a back-and-forth relationship with the narrow wall 62b on the bottom side of the rectangular waveguide 62. The narrow wall 54a on the ceiling side of the cutoff waveguide 54 is formed with a plurality of reflection suppressing slots 58 at predetermined intervals. Each reflection suppressing slot 58 has a different slot length. In the radiator 15 of this embodiment, the vibration mode in the rectangular waveguide 62 is a traveling wave excitation.

[0045] Fig. 13 is a view taken along the arrow BB of the slot array antenna 11 shown in Fig. 12. The plane taken along the arrow BB is the surface of the reflection suppressing slot plate 56 which constitutes the narrow wall on the ceiling side of the cutoff waveguide 54. The reflection suppressing slot plate 56 constitutes a part of the bottom plate 51 of the radiator 15. The bottom plate 51 also serves as the top plate of the feed tube 32. The reflection suppressing slot plate 56 has four rows of H-shaped reflection suppressing slots 58 formed on each side of the feed port 52, aligned with the positions of the four cutoff waveguides 54 on each side.

[0046] 14 is an exploded perspective view showing the slot array antenna 11. As shown in this exploded perspective view, the slot array antenna 11 is composed of a feeder 12 and a radiator 15. The radiator 15 is composed of a bottom plate 51, a radiating base body 60 constituting a rectangular waveguide 62, and a slot plate 70 in which radiating slots 72 and 74 are formed, which are laminated together. The bottom plate 51 is composed of a reflection-suppressing slot plate 56 in which a reflection-suppressing slot 58 is formed, and a cutoff waveguide body 53 in which a cutoff waveguide 54 is formed, which are laminated together. Moreover, the radiating slots 72 and 74 in this embodiment are I-shaped slots with a slot angle of 49 degrees, and the radiating slots 72 and 74 are symmetrical to each other. [Explanation of symbols]

[0047] 10 Slot array antenna (first embodiment) 11 Slot array antenna (second embodiment) 12 Power feeder 14 Emitter 20 Bottom plate 30 Power supply base body 32 Feed tube 36 Reflection Suppression Wall 36A, 36B, 36C connection plate 38 Reflection Suppression Wall 38A, 38B connection plate 40 thin plate 50 Tabletop 51 Bottom plate 52 Power supply port 53 Cut-off Waveguide Body 54 Cutoff Waveguide 56 Reflection suppression slot plate 58 Reflection Suppression Slot 60 Radiation Base Body 62 Rectangular waveguide 70 Slot plate 72, 74 Radiation slot 80 Radome 82 Grid

Claims

1. A slot array antenna for use in millimeter waves or higher frequency bands, A radiator in which a plurality of rectangular waveguides, each of which has a closed end, are arranged in parallel; a feeder body having a feed tube having a rectangular cross-sectional shape and connected to each of the plurality of rectangular waveguides; The radiator is a slot plate constituting a narrow wall on the ceiling side of each of the rectangular waveguides, the slot plate having a plurality of radiation slots formed at predetermined intervals on the narrow wall; a radiating base body having a plurality of holes formed therein, the holes defining the broad walls and end walls of each of the plurality of rectangular waveguides; a bottom plate constituting a narrow wall on the bottom side of each of the rectangular waveguides, the bottom plate having a feed port that opens at the center of each of the rectangular waveguides and connects each of the rectangular waveguides to the feed tube; The power supply body is a top plate that constitutes a top surface of the feed tube and has the feed ports formed on the top surface, the feed ports connecting each of the rectangular waveguides to the feed tube; a power supply base body having a notch formed therein that constitutes a side wall and a rear wall of the power supply pipe; A bottom plate that constitutes a bottom surface of the power supply pipe, The power supply base body is a laminate of a plurality of thin plates, A part of the plurality of thin plates that do not overlap each other among the plurality of thin plates excluding the top layer and the bottom layer thin plates includes a connecting plate connecting the side walls on both sides, The reflection suppressing wall is formed by a plurality of connecting plates provided on the plurality of thin plates. A slot array antenna characterized by:

2. 2. The slot array antenna according to claim 1, the reflection suppression wall includes a first reflection suppression wall provided at a corner formed by the bottom surface and the back wall of the feed tube, The plurality of connecting plates constituting the first reflection suppressing wall are arranged such that the connecting plates farther from the bottom surface have a shorter distance from the back wall to the edge of the opening than the connecting plates closer to the bottom surface. A slot array antenna characterized by:

3. 3. The slot array antenna according to claim 1, The reflection suppressing wall includes a second reflection suppressing wall provided on the opening side of the power supply port. A slot array antenna characterized by:

4. 2. The slot array antenna according to claim 1, The power supply pipe has a front portion where a distance between side walls increases from an opening toward the back wall; a rear portion in which the distance between the side walls is constant up to the rear wall; The power supply port is provided at the rear portion at a distance from the back wall. A slot array antenna characterized by:

5. 2. The slot array antenna according to claim 1, The bottom plate of the radiator also serves as the top plate of the power feeder. A slot array antenna characterized by:

6. 2. The slot array antenna according to claim 1, the radiating slot is an asymmetric I-slot; The asymmetric I-slot is left and right longitudinal slots extending along the length of said narrow wall; a horizontal slot extending in the width direction of the narrow wall and connecting the left and right vertical slots; one of the left and right vertical slots is connected to the horizontal slot at a position closer to one end of the narrow wall than the center; the other of the left and right vertical slots is connected to the horizontal slot at a position closer to the other end of the narrow wall than the center; The positional relationship between the left and right vertical slots and the horizontal slots is reversed between adjacent asymmetric I-shaped slots. A slot array antenna characterized by:

7. 2. The slot array antenna according to claim 1, The bottom plate is a cutoff waveguide body in which a plurality of cutoff waveguides, each having a closed end, are arranged in parallel; a reflection-suppressing slot plate having a plurality of reflection-suppressing slots formed corresponding to the plurality of cutoff waveguides; the reflection-repressing slot plate constitutes the top surfaces of the plurality of cutoff waveguides and the bottom surfaces of the plurality of rectangular waveguides; The cutoff waveguides and the rectangular waveguides are connected to each other through at least one of the reflection-suppressing slots. A slot array antenna characterized by:

8. The slot array antenna according to claim 7, The plurality of reflection suppressing slots includes a plurality of reflection suppressing slots with different amounts of reflection. A slot array antenna characterized by:

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