Radio wave absorbing device

Abstract

A radio wave absorbing device according to one aspect of the present disclosure is provided with a first dielectric substrate (41), a second dielectric substrate (42), a first conductor layer (53) provided with slits (58A, 58B), a passive element (31), a second conductor layer (54), and a metal wall (55) penetrating the second dielectric substrate. The metal wall shifts the phase of the second reflected wave (W3) from the phase of the first reflected wave (W1). A part of an incoming wave (W0) that reaches the first outer surface of the first dielectric substrate is reflected by at least one of the passive element and the periphery thereof and the first conductor layer to generate a first reflected wave. The other part of the incoming wave enters the second dielectric substrate through the passive element and the slit, and is reflected by the metal wall to generate a second reflected wave.

Description

[0001] Cross - reference to related applications

[0002] This international application claims the priority of Japanese Patent Application No. 2022 - 188520 filed with the Japan Patent Office on November 25, 2022, and Japanese Patent Application No. 2023 - 193786 filed with the Japan Patent Office on November 14, 2023, and incorporates the entire contents thereof herein by reference. Technical field

[0003] This disclosure relates to a radio wave absorption device. Background art

[0004] In the antenna device described in Patent Document 1, the polarization wave of the reflected wave generated by reflecting the radiation wave on the secondary surface and then reflecting it again in the antenna device becomes the polarization wave of the radiation wave from the antenna portion. Thus, the above - mentioned antenna device suppresses the interference of unwanted reflected waves with the radiation wave and suppresses the unstable directivity of the antenna.

[0005] Patent Document 1: Japanese Patent No. 6705784 Gazette

[0006] The above - mentioned antenna device suppresses the interference with the radiation wave by changing the polarization wave of the reflected wave, but does not reduce the reflected wave. Therefore, there is a possibility that the reflected wave may affect something other than the radiation wave. Summary of the invention

[0007] One aspect of this disclosure provides a radio wave absorption device capable of reducing unwanted reflected waves.

[0008] The radio wave absorption device according to one aspect of this disclosure includes a first dielectric substrate, a second dielectric substrate, a first conductor layer, a passive element, a second conductor layer, a first end portion, and a metal wall. The first dielectric substrate has a first outer surface and a first inner surface. The second dielectric substrate has a second outer surface and a second inner surface. The first conductor layer is provided with a slit and is configured to be in contact with the first inner surface and the second inner surface. The passive element is disposed on the first outer surface. The second conductor layer is disposed on the second outer surface. The metal wall has a first end portion in contact with the first conductor layer and a second end portion in contact with the second conductor layer and penetrates the second dielectric substrate. The metal wall is configured to shift the phase of the second reflected wave from the phase of the first reflected wave. A part of the incident wave reaching the first outer surface is reflected at at least one of the passive element, the periphery of the passive element, and the above - mentioned first conductor layer to generate a first reflected wave, and the other part of the incident wave enters the second dielectric substrate through the passive element and the slit and is reflected at the metal wall to generate a second reflected wave.

[0009] In the radio wave absorption device according to one aspect of the present disclosure, a part of the incident wave is reflected on the first outer surface to generate a first reflected wave, and another part of the incident wave enters the second dielectric substrate and is reflected on the metal wall to generate a second reflected wave. Since the phase of the second reflected wave is shifted from the phase of the first reflected wave, the second reflected wave cancels out the first reflected wave. Therefore, unnecessary reflected waves can be reduced.

[0010] The radio wave absorption device according to another aspect of the present disclosure includes a waveguide, a first end portion, and a metal wall. The waveguide is a metal waveguide having a first wall surface provided with a first slit that functions as a passive element and a second wall surface opposed to the first wall surface. The metal wall has a first end portion in contact with the first wall surface and a second end portion in contact with the second wall surface, and the metal wall divides the interior of the waveguide. The metal wall is configured to shift the phase of the second reflected wave from the phase of the first reflected wave, and a part of the incident wave reaching the first wall surface is reflected around the first slit to generate a first reflected wave, and another part of the incident wave enters the interior of the waveguide through the first slit and is reflected on the metal wall to generate a second reflected wave.

[0011] In another radio wave absorption device of the present disclosure, a part of the incident wave is reflected on the first wall surface to generate a first reflected wave, and another part of the incident wave is incident into the waveguide and is reflected on the metal wall to generate a second reflected wave. Since the phase of the second reflected wave is shifted from the phase of the first reflected wave, the second reflected wave cancels out the first reflected wave. Therefore, unnecessary reflected waves can be reduced. BRIEF DESCRIPTION OF THE DRAWINGS

[0012] Figure 1 It is a schematic diagram showing the upper surface of the antenna device according to the first embodiment.

[0013] Figure 2 It is a schematic diagram showing the heat loss of the incident wave incident into the substrate on the vertical cross-section cut along the II-II' line in the first example of the first embodiment of the first embodiment. Figure 1 of the incident wave incident into the substrate on the vertical cross-section cut along the II-II' line in the first example of the first embodiment of the first embodiment.

[0014] Figure 3A It is a schematic diagram showing the second reflected wave generated by the reflection of the incident wave on the metal wall in the substrate on the vertical cross-section cut along the II-II' line in the first example of the first embodiment of the first embodiment. Figure 1 of the incident wave incident into the substrate on the vertical cross-section cut along the II-II' line in the first example of the first embodiment of the first embodiment.

[0015] Figure 3B It is a schematic diagram showing the distance from the metal wall to the slit in the first example of the first embodiment of the first embodiment.

[0016] Figure 4It is a diagram showing the radiated wave radiated from the antenna device of the reference example, and the reflected wave generated by the reflection of the radiated wave on the secondary surface and the re - reflection on the antenna device.

[0017] Figure 5 It is a diagram showing the directivity gain of the antenna device of the reference example without a secondary surface and the directivity gain of the antenna device of the reference example with a secondary surface.

[0018] Figure 6 It is a schematic diagram showing the horizontal cross - section of the slit and the metal wall of the first embodiment of the first implementation manner.

[0019] Figure 7 It is a schematic diagram showing the horizontal cross - section of the passive element of the second embodiment of the first implementation manner.

[0020] Figure 8 It is a schematic diagram showing the horizontal cross - section of the slit and the metal wall of the third embodiment of the first implementation manner.

[0021] Figure 9 It is a schematic diagram showing the horizontal cross - section of the slit and the metal wall of the fourth embodiment of the first implementation manner.

[0022] Figure 10 It is a schematic diagram showing the horizontal cross - section of the slit and the metal wall of the fifth embodiment of the first implementation manner.

[0023] Figure 11 It is a schematic diagram showing the horizontal cross - section of the slit of the sixth embodiment of the first implementation manner.

[0024] Figure 12 It is a schematic diagram showing the horizontal cross - section of the slit and the metal wall of the seventh embodiment of the first implementation manner.

[0025] Figure 13 It is a schematic diagram showing the horizontal cross - section of the slit of the eighth embodiment of the first implementation manner.

[0026] Figure 14 It is a schematic diagram showing the upper surface of the antenna device of the second implementation manner.

[0027] Figure 15 It is a schematic diagram showing the vertical cross - section cut along the XV - XV' line of the first embodiment of the second implementation manner at Figure 14

[0028] Figure 16 It is a schematic diagram showing the vertical cross - section cut along the XV - XV' line of the second embodiment of the second implementation manner at Figure 14 Detailed implementation manners

[0029] (First Embodiment)

[0030] <1-1. First Embodiment>

[0031] Refer to Figures 1 to 3B , and the antenna device 10A of the first embodiment of the first embodiment will be described.

[0032] The antenna device 10A is a multilayer substrate including a first dielectric substrate 41, a second dielectric substrate 42, a first conductor layer 53, a second conductor layer 54, a substrate pattern layer 51, a metal wall 55, and a through hole 56. The antenna device 10A is formed by laminating a plurality of substrates each having a long side extending in the x-axis direction and a short side extending in the y-axis direction in the z-axis direction. The antenna device 10A is, for example, a millimeter-wave band in-vehicle planar array antenna mounted inside the front or rear bumper of a vehicle. In addition, the antenna device 10A corresponds to the radio wave absorption device of the present disclosure.

[0033] The first dielectric substrate 41 has a first outer surface 41a and a first inner surface 41b. The first dielectric substrate 41 is made of a first material or has a first structure. The second dielectric substrate 42 has a second outer surface 42a and a second inner surface 42b. The second dielectric substrate 42 is made of a second material or has a second structure. The second material has a greater energy loss of radio waves than the first material. In addition, the second structure has a greater energy loss of radio waves than the first structure. That is, the tangent of the dielectric loss of the second dielectric substrate 42 is greater than the tangent of the dielectric loss of the first dielectric substrate 41, and in the second dielectric substrate 42, a larger amount of radio waves are dissipated in the form of heat compared to the first dielectric substrate 41.

[0034] The first conductor layer 53 is disposed between the first dielectric substrate 41 and the second dielectric substrate 42 in contact with the first inner surface 41b and the second inner surface 42b. The second conductor layer 54 is disposed in contact with the second outer surface 42a. The first conductor layer 53 and the second conductor layer 54 are patterns of metal (for example, copper). A slit 58A is formed in the first conductor layer 53. The second conductor layer 54 corresponds to a ground layer.

[0035] The substrate pattern layer 51 is a conductor pattern disposed on the first outer surface 41a. As Figure 1As shown, the substrate pattern layer 51 includes M antenna arrays 20 and N passive arrays 30. M and N are natural numbers. In the present embodiment, the substrate pattern layer 51 includes four antenna arrays 20 and seven passive arrays 30. The M antenna arrays 20 and the N passive arrays 30 are arranged at equal intervals in the x-axis direction with the extending direction of the arrays along the y-axis direction. Specifically, each antenna array 20 is sandwiched by two passive arrays 30. That is, in the x-axis direction, the antenna arrays 20 and the passive arrays 30 are alternately arranged. The passive arrays 30 are connected to the first conductor layer 53 via vias 56.

[0036] Each antenna array 20 has L antenna elements 21. Each antenna element 21 is a square conductor patch. L is a natural number. The L antenna elements 21 are arranged at equal intervals along the y-axis direction and are connected to each other by transmission lines 21a. In the present embodiment, each antenna array 20 has five antenna elements 21. Each antenna element 21 is a radiating antenna element. For example, it receives power supply of high-frequency signals from the back surface of the multilayer substrate and radiates radio waves.

[0037] Each passive array 30 has L passive elements 31. Each passive element 31 is a square conductor patch. The L passive elements 31 are arranged at equal intervals along the y-axis direction and are connected to each other by transmission lines 31a. In the present embodiment, each passive array 30 has five passive elements 31. The passive array 30 receives a part of the incoming wave W0 reaching the antenna device 10A.

[0038] In Figure 4 An antenna device 100 showing a reference example and a secondary surface 110 arranged in front of the antenna device 100 are shown. The secondary surface 110 is, for example, a bumper. A part of the radiation wave radiated from the antenna device 100 is reflected by the secondary surface 110 to generate a reflected wave. The reflected wave reaches the antenna device 100 and is re-reflected by the antenna device 100. Since the reflected wave is re-reflected, a re-reflected wave is generated. The re-reflected wave is radiated in front of the antenna device 100 and interferes with the radiation wave directly radiated from the antenna device 100. As a result, as Figure 5 shown, in front of the antenna device 100, the directivity gain of the antenna device 100 is reduced.

[0039] In the present embodiment, the antenna device 10A has passive elements 31 around the antenna elements 21. Therefore, as Figure 2As shown in FIG. 3A, a part of the reflected wave (hereinafter referred to as the incoming wave) W0 having a wavelength λ reaching the antenna device 10A is received by the passive element 31, and the re-reflection at the antenna device 10A is suppressed. Another part of the incoming wave W0 is not received by the passive element 31 and is reflected on the first outer surface 41a and / or the first conductor layer 53 to become the first reflected wave W1 having a wavelength λ. Another part of the incoming wave W0 is reflected by at least one of the region on the first outer surface 41a where the passive element 31 is not disposed (i.e., the periphery of the passive element 31), the passive element 31, and the first conductor layer 53.

[0040] In addition, the M antenna arrays 20 and the N passive arrays 30 may not necessarily be arranged at equal intervals in the x-axis direction, but may be arranged at unequal intervals in the x-axis direction. Even if the M antenna arrays 20 are arranged at unequal intervals in the x-axis direction, radio waves can be transmitted in a specified direction. In addition, even if the N passive arrays 30 are arranged at unequal intervals in the x-axis direction, a part of the incoming wave W0 can be received by the N passive arrays 30.

[0041] In addition, the passive array 30 may be disposed on the first outer surface 41a other than beside the antenna array 20, or may be disposed at other positions in addition to beside the antenna array 20. In addition, the passive array 30 may be disposed on a surface other than the first outer surface 41a, or may be disposed on other surfaces in addition to the first outer surface 41a.

[0042] When the secondary surface 110 is parallel to the first outer surface 41a (specifically, when the secondary surface 110 is perpendicular to the radiation direction of the radio wave from the antenna array 20), the incoming wave W0 returns to the first outer surface 41a. However, when the secondary surface 110 is inclined with respect to the first outer surface 41a (specifically, when the secondary surface 110 is not perpendicular to the radiation direction of the radio wave), the incoming wave W0 returns to a position different from the first outer surface 41a. Therefore, a substrate different from the antenna device 10A may be disposed in the direction where the incoming wave W0 returns based on the inclination of the secondary surface 110 with respect to the first outer surface 41a, and the passive array 30 may be disposed on the surface of the substrate. If the passive array 30 is disposed in this way, even when the secondary surface 110 is inclined with respect to the first outer surface 41a, a part of the incoming wave W0 can be received by the passive element 31, and unnecessary reflected waves can be reduced.

[0043] In addition, the antenna element 21 and the passive element 31 are not limited to square conductor patches, and may also be circular or elliptical conductor patches. Additionally, instead of the M antenna arrays 20, M×L patch antennas may be provided on the first outer surface 41a, and the M×L patch antennas receive power supply to radiate radio waves. Further, instead of the N passive arrays 30, N×L patch antennas may be provided on the first outer surface 41a, and the N×L patch antennas receive a part of the incoming wave W0.

[0044] A part of the incoming wave W0 received by the passive element 31 becomes an incident wave W2 having a wavelength λ that enters the multilayer substrate of the antenna device 10A. Here, there may be a case where the incident wave W2 is reflected inside the substrate to generate a reflected wave, and the reflected wave is radiated from the antenna device 10A. In the present embodiment, in order to suppress the radiation of such a reflected wave, the incident wave W2 is dissipated in the multilayer substrate in the form of heat.

[0045] However, the high-frequency signal supplied to the antenna array 20 is transmitted in the first dielectric substrate 41. Therefore, if the first dielectric substrate 41 is made of a material or structure with a large amount of radio wave heat loss, the radiation wave radiated from the antenna device 10A is attenuated. Thus, in the antenna device 10A of the present embodiment, the energy loss of the radio wave in the second dielectric substrate 42 is made larger than the energy loss of the radio wave in the first dielectric substrate 41, and the incident wave W2 is dissipated in the second dielectric substrate 42 in the form of heat.

[0046] Specifically, the first conductor layer 53 has a slit 58A. The slit 58A is disposed at a position overlapping the passive element 31 in the z-axis direction. One slit 58A is disposed for one passive element 31. That is, in the present embodiment, N×L slits 58A are formed in the first conductor layer 53. The slit 58A extends in a direction perpendicular to the extending direction of the passive array 30 (i.e., the x-axis direction). In the z-axis direction, the slit 58A may completely overlap the passive element 31 or may partially overlap.

[0047] As Figure 2 shown, by disposing the slit 58A at a position overlapping the passive element 31 in the z-axis direction, the incident wave W2 incident from the passive element 31 enters the second dielectric substrate 42 via the slit 58A. Additionally, by disposing the slit 58A at a position overlapping the passive element 31 in the z-axis direction, it is possible to suppress the high-frequency signal supplied to the transmission line 21a from propagating to the second dielectric substrate 42 via the slit 58A.

[0048] A metal wall 55 is disposed on the second dielectric substrate 42. The metal wall 55 has a first end in contact with the first conductor layer 53 and a second end in contact with the second conductor layer 54, and penetrates the second dielectric substrate 42. The first end of the metal wall 55 surrounds the entire periphery of the slit 58A formed in the first conductor layer 53.

[0049] The metal wall 55 may also be composed of a plurality of metal vias 55a. That is, the metal wall 55 may also be composed of a plurality of metal vias 55a arranged in a square, circular, elliptical, etc. at a prescribed interval so as to surround the slit 58A in the xy plane. The prescribed interval may be a distance at which the incident wave W2 does not leak from the metal wall 55 according to the wavelength of the incident wave W2.

[0050] Figure 6 A horizontal cross-section of the second dielectric substrate 42 of the antenna device 10A of the first embodiment of the first embodiment is schematically shown. As Figure 6 shown, the metal wall 55 surrounds the entirety of the N slits 58A. In addition, the metal wall 55 may independently surround the N slits 58A. That is, in the first conductor layer 53, the first end of the metal wall 55 may be in contact with two adjacent slits 58A in the x-axis direction. Alternatively, the N slits 58A may be divided into two or more groups, and the metal wall 55 may surround each group.

[0051] Alternatively, the metal wall 55 may be composed of a plate-like member made of metal. That is, the metal wall 55 may also be formed by bending a plate-like member made of metal so that the xy cross-sectional shape is square, circular, elliptical, etc.

[0052] By surrounding the slit 58A with the metal wall 55, the incident wave W2 enters the inside of the metal wall 55 via the slit 58A. The incident wave W2 is repeatedly diffusely reflected inside the metal wall 55 and dissipated in the form of heat. Thereby, unnecessary reflected waves radiated from the antenna device 10A can be suppressed.

[0053] However, as Figure 3AAs shown, there may be a case where the second reflected wave W3 generated by the reflection of the incident wave W2 on the metal wall 55 is radiated from the passive element 31 via the slit 58A and the first dielectric substrate 41. Therefore, in the antenna device 10A of the present embodiment, in order to further suppress unnecessary reflected waves, the length of the distance LL1 is formed so that the phase of the second reflected wave W3 is shifted from the phase of the first reflected wave W1. The distance LL1 is the length between the slit 58A and the metal wall 55 in the direction along the first dielectric substrate 41. Specifically, the distance LL1 is the length from one of the two metal walls 55 opposed in the y-axis direction to the slit 58A. The distance LL2 is the length from the other of the two metal walls 55 opposed in the y-axis direction to the slit 58A, and the distance LL2 < the distance LL1. In addition, it is also possible that the distance LL2 = the distance LL1.

[0054] If the phase of the second reflected wave W3 is shifted from the phase of the first reflected wave W1, the second reflected wave W3 cancels out the first reflected wave W1, further suppressing unnecessary reflected waves. When the phase of the second reflected wave W3 is shifted by 180 degrees from the phase of the first reflected wave W1, the energy at which the second reflected wave W3 cancels out the first reflected wave W1 is the maximum. Thus, in the present embodiment, the distance LL1 is formed to be a length at which the phase of the second reflected wave W3 becomes the opposite phase to the phase of the first reflected wave W1.

[0055] Specifically, as Figure 3BAs shown, in this embodiment, the distance LL1 is formed to be a length of (2K - 1)×λ / 4, that is, an odd multiple of a quarter of the wavelength λ. K is a natural number. The first reflected wave W1 generated by reflection from the first conductor layer 53 is phase - inverted by reflection from the first conductor layer 53. That is, the phase of the first reflected wave W1 is offset by λ / 2 compared to the phase of the incident wave W2. On the other hand, the phase of the second reflected wave W3 is offset by λ / 2 due to reflection from the metal wall 55 compared to the phase of the incident wave W2, and is offset by the round - trip amount of the distance LL1. Therefore, on the reference plane, the phase of the second reflected wave W3 is offset by the round - trip amount of the distance LL1 compared to the phase of the first reflected wave W1. The reference plane is a virtual plane disposed above the substrate pattern layer 51 and is a plane parallel to the substrate pattern layer 51. If the distance LL1 is formed to be an odd multiple of a quarter of the wavelength λ, the phase offset of the round - trip amount of the distance LL1 becomes an odd multiple of a half of the wavelength λ. Therefore, if the distance LL1 is formed to be an odd multiple of a quarter of the wavelength λ, the phase of the second reflected wave W3 becomes the opposite phase of the phase of the first reflected wave W1. In addition, even if the phase of the second reflected wave W3 is not the opposite phase of the phase of the first reflected wave W1 but only offset, the second reflected wave W3 cancels out some of the first reflected wave W1, and unwanted reflected waves can be suppressed. Therefore, as long as the distance LL1 is a length such that the phase of the second reflected wave W3 is not the same as the phase of the first reflected wave W1, it does not necessarily have to be a length that results in the opposite phase.

[0056] According to the first embodiment of the first embodiment described above, the following effects are achieved.

[0057] (1) The incident wave W2 received by the passive element 31 enters the second dielectric substrate 42 via the slit 58A and is dissipated in the second dielectric substrate 42 in the form of heat. Therefore, unwanted reflected waves generated by the reflection of the incident wave W2 in the antenna device 10A can be reduced.

[0058] (2) The second dielectric substrate 42 is made of a material or structure with a greater energy loss of electric waves compared to the first dielectric substrate 41. Therefore, when the antenna element 21 is disposed on the first outer surface 41a of the first dielectric substrate 41, while the electric wave can be transmitted and radiated in the first dielectric substrate 41, the incident wave W2 can be dissipated in the second dielectric substrate 42 in the form of heat.

[0059] (3) Since the distance LL1 is formed such that the phase of the second reflected wave W3 is offset from the phase of the first reflected wave W1, the second reflected wave W3 cancels out the first reflected wave W1. Therefore, unwanted reflected waves can be reduced.

[0060] (4)When the distance LL1 is formed such that the phase of the second reflected wave W3 becomes opposite to the phase of the first reflected wave W1, the unwanted reflected wave can be minimized. By forming the distance LL1 to be a quarter of the wavelength λ, the phase of the second reflected wave W3 can be made opposite to the phase of the first reflected wave W1.

[0061] (5)By disposing the metal wall 55 on the second dielectric substrate 42, the incident wave W2 enters the second dielectric substrate 42 surrounded by the metal wall 55 from the slit 58A. Since the incident wave W2 undergoes diffuse reflection on the metal wall 55, the amount of heat loss of the incident wave W2 increases compared to the case where it is not surrounded by the metal wall 55, and the incident wave W2 can be further reduced. In addition, since the incident wave W2 undergoes diffuse reflection, the second reflected wave W3 generated by the diffuse reflection of the incident wave W2 is not easily returned to the slit 58A, and the re-radiation of the second reflected wave W3 can be suppressed. Furthermore, the unwanted reflected wave can be further reduced.

[0062] (6)In the stacking direction, the passive element 31 overlaps with the slit 58A, so it is easy for the incident wave W2 received by the passive element 31 to enter the second dielectric substrate 42 via the slit 58A. In addition, the high-frequency signal supplied to the antenna element 21 can be suppressed from propagating into the second dielectric substrate 42.

[0063] <1-2. Second Embodiment>

[0064] Since the basic configuration of the second embodiment of the first embodiment is the same as that of the first embodiment of the first embodiment, the differences will be described below. In addition, the same reference numerals as those in the first embodiment of the first embodiment represent the same configurations, and refer to the foregoing description.

[0065] As Figure 7 shown, the antenna device 10A of the second embodiment further includes a protective layer 32. The protective layer 32 is disposed above the terminal portions of the N passive arrays 30 and covers the terminal portions. Thereby, the amount of heat loss of the incident wave W2 can be further increased.

[0066] <1-3. Third Embodiment>

[0067] Since the basic configuration of the third embodiment of the first embodiment is the same as that of the first embodiment of the first embodiment, the differences will be described below. In addition, the same reference numerals as those in the first embodiment of the first embodiment represent the same configurations, and refer to the foregoing description.

[0068] As Figure 8As shown, the antenna device 10A of the third embodiment includes a plurality of inner through-holes 55b. The plurality of inner through-holes 55b are arranged inside the metal wall 55. The plurality of inner through-holes 55b penetrate the second dielectric substrate 42 and are in contact with the first conductor layer 53 and the second conductor layer 54.

[0069] By providing a plurality of inner through-holes 55b, when the incident wave W2 is directed toward the metal wall 55 (i.e., the metal through-hole 55a), a second reflected wave W3 is generated by reflection in the inner through-hole 55b midway, and the second reflected wave W3 propagates in various directions. As a result, the path along which the second reflected wave W3 propagates inside the metal wall 55 becomes longer, and the amount of heat dissipation of the second reflected wave W3 increases. In addition, since the second reflected wave W3 propagates in various directions, the second reflected wave W3 is not easily returned to the slit 58A. Furthermore, radiation of the second reflected wave W3 from the antenna device 10A can be further suppressed.

[0070] <1-4. Fourth Embodiment>

[0071] Since the basic configuration of the fourth embodiment of the first embodiment is the same as that of the first embodiment of the first embodiment, the differences will be described below. In addition, the same reference numerals as those in the first embodiment of the first embodiment denote the same configurations, and reference is made to the foregoing description.

[0072] As Figure 9 shown, in the first conductor layer 53 of the antenna device 10A of the fourth embodiment, N×L slits 58B are formed instead of the N×L slits 58A. The slit 58A is formed to extend parallel to the x-axis direction, but the slit 58B is formed to extend at a specified angle with respect to the x-axis direction. The specified angle is, for example, 45 degrees.

[0073] Since the slit 58B is inclined with respect to the x-axis direction, the path along which the incident wave W2 entering the inside of the metal wall 55 from the slit 58B propagates inside the metal wall 55 becomes longer. As a result, the amount of heat dissipation of the incident wave W2 can be increased, and radiation of the second reflected wave W3 from the antenna device 10A can be suppressed.

[0074] <1-5. Fifth Embodiment>

[0075] Since the basic configuration of the fifth embodiment of the first embodiment is the same as that of the first embodiment of the first embodiment, the differences will be described below. In addition, the same reference numerals as those in the first embodiment of the first embodiment denote the same configurations, and reference is made to the foregoing description.

[0076] As Figure 10As shown, the metal wall 55 of the antenna device 10A of the fifth embodiment has two sides parallel to the y-axis, one side parallel to the x-axis, and one side non-parallel to the x-axis. The side non-parallel to the x-axis arranges a plurality of metal through-holes 55a into two convex shapes. Since the metal wall 55 has a side non-parallel to the x-axis, the second reflected wave W3 generated by the reflection of the incident wave W2 on the non-parallel side propagates in various directions. Therefore, the second reflected wave W3 is not easily returned to the slit 58A. Furthermore, the radiation of the second reflected wave W3 from the antenna device 10A can be suppressed. In addition, the side non-parallel to the x-axis may have one convex shape or may have three or more convex shapes.

[0077] <1 - 6. Sixth Embodiment>

[0078] Since the basic configuration of the sixth embodiment of the first embodiment is the same as that of the first embodiment of the first embodiment, the differences will be described below. In addition, the same reference numerals as those in the first embodiment of the first embodiment represent the same configurations, and refer to the foregoing description.

[0079] As Figure 11 shown, the antenna device 10A of the sixth embodiment does not include the metal wall 55. In such an antenna device 10A, it is also possible to dissipate the incident wave W2 in the form of heat throughout the second dielectric substrate 42 and suppress unwanted reflected waves.

[0080] <1 - 7. Seventh Embodiment>

[0081] Since the basic configuration of the seventh embodiment of the first embodiment is the same as that of the first embodiment of the first embodiment, the differences will be described below. In addition, the same reference numerals as those in the first embodiment of the first embodiment represent the same configurations, and refer to the foregoing description.

[0082] As Figure 12 shown, the antenna device 10A of the seventh embodiment surrounds the periphery of each slit 58A with a metal wall 55, and the length of the distance LL1 is different for each slit 58A. For example, when the distance LL1 = (2K - 1)×λ / 4, the value of K is increased sequentially along the arrangement of the slits 58A. Thereby, for the passive array 30, the phase of the second reflected wave W3 can be controlled, and the reflection direction of the second reflected wave W3 can be controlled.

[0083] <1 - 8. Eighth Embodiment>

[0084] Since the basic configuration of the eighth embodiment of the first embodiment is the same as that of the first embodiment of the first embodiment, the differences will be described below. In addition, the same reference numerals as those in the first embodiment of the first embodiment represent the same configurations, and refer to the foregoing description.

[0085] AsFigure 13 As shown, the antenna device 10A of the eighth embodiment controls the phase of the second reflected wave W3 using not only the distance LL1 but also the distance LL2. That is, in the eighth embodiment, the distance LL2 is formed such that the phase of the second reflected wave W3 is offset from the phase of the first reflected wave W1 (for example, becomes the opposite phase). Thereby, unnecessary reflected waves can be further suppressed.

[0086] (Second Embodiment)

[0087] <2-1. Differences from the First Embodiment>

[0088] Since the basic configuration of the second embodiment is the same as that of the first embodiment, the differences will be described below. In addition, the same reference numerals as those in the first embodiment represent the same configuration, and refer to the foregoing description.

[0089] The antenna device 10A of the above-described first embodiment is a planar array antenna. In contrast, the antenna device 10B of the second embodiment is different from the first embodiment in that it is a waveguide slot array antenna.

[0090] <2-2. First Example>

[0091] Refer to Figure 14 and 15 to describe the antenna device 10B of the second example of the second embodiment. The antenna device 10B corresponds to the radio wave absorption device of the present disclosure.

[0092] The antenna device 10B includes a waveguide 80. The waveguide 80 is a square hollow waveguide having a square cross-section in the xz plane. The waveguide 80 includes upper walls 82 along the x-axis and y-axis directions. The waveguide 80 forms M feed slot arrays 60 and N passive slot arrays 70 on the surface of the upper wall 82. In the present embodiment, four feed slot arrays 60 and seven passive slot arrays 70 are formed on the surface of the upper wall 82. The M feed slot arrays 60 and the N passive slot arrays 70 are arranged at equal intervals in the x-axis direction with the extending direction of the array along the y-axis direction. Specifically, each feed slot array 60 is sandwiched by two passive slot arrays 70. That is, in the x-axis direction, the feed slot arrays 60 and the passive slot arrays 70 are alternately arranged.

[0093] The waveguide 80 includes a plurality of partition walls 81. Each partition wall 81 has a first end and a second end, the first end is connected to the upper wall 82, and the second end is connected to the bottom wall 83. Each partition wall 81 extends in the y-axis direction. The plurality of partition walls 81 are arranged between the feed slot arrays 60 and the passive slot arrays 70, between the passive slot arrays 70 and the passive slot arrays 70, and at the ends of the two passive slot arrays 70 arranged at the ends in the x-axis direction.

[0094] Each feed slot array 60 has L feed slots 61. Each feed slot 61 is formed to extend parallel to the x-axis direction. The positions of the L feed slots 61 in the x-axis direction are not the same, and the positions are gradually offset along the x-axis direction. In the present embodiment, each feed slot array 60 has five feed slots 61. Each feed slot 61 is a radiating antenna element, for example, receiving power supply of a high-frequency signal from the back surface of the waveguide 80 and radiating radio waves.

[0095] Each passive slot array 70 has L passive slots 71. Each passive slot 71 is formed to extend parallel to the x-axis direction. The L passive slots 71 are the same as the L feed slots 61, and the positions are gradually offset along the x-axis direction. The passive slot array 70 receives a part of the incoming wave W0 reaching the antenna device 10B.

[0096] The waveguide 80 has a structure in which the energy loss of radio waves is larger than the spatial attenuation. Therefore, the incident wave W2 incident into the waveguide 80 via the passive slot array 70 is dissipated in the waveguide 80 in the form of heat.

[0097] And, as Figure 15 shown, the waveguide 80 includes a metal wall 75. A metal wall 75 is provided for each passive slot 71. The metal wall 75 has a first end and a second end, the first end is connected to the upper wall 82, and the second end is connected to the bottom wall 83. The metal wall 75 is a wall parallel to the x-axis direction and is connected to two adjacent partition walls 81. Moreover, the first ends of the two metal walls 75 and the first ends of the two partition walls 81 surround the passive slot 71.

[0098] Since the two metal walls 75 and the two partition walls 81 surround the passive slot 71, the incident wave W2 enters the interior surrounded by the two metal walls 75 and the two partition walls 81 via the passive slot 71, and is repeatedly diffusely reflected and dissipated in the form of heat. Thereby, unnecessary reflected waves radiated from the antenna device 10B can be suppressed.

[0099] And, the length of the distance LL3 is formed such that the phase of the second reflected wave W3 is offset from the phase of the first reflected wave W1. The distance LL3 is the length in the y-axis direction from at least one of the two metal walls 75 to the passive slot 71.

[0100] In the present embodiment, the distance LL3 is formed to be a length such that the phase of the second reflected wave W3 becomes a phase opposite to the phase of the first reflected wave W1. In addition, as long as the distance LL3 is a distance such that the phase of the second reflected wave W3 does not become the same as the phase of the first reflected wave W1, it does not necessarily have to be a distance that becomes the opposite phase.

[0101] According to the second embodiment of the first embodiment described above, the following effects are achieved.

[0102] (7) The incident wave W2 received by the passive slot 71 enters the waveguide 80 and dissipates in the waveguide 80 in the form of heat. Therefore, the unwanted reflected wave generated by the reflection of the incident wave W2 by the antenna device 10B can be reduced.

[0103] (8) The energy loss of the electric wave in the waveguide 80 is greater than the space attenuation. Therefore, when the feeding slot 61 is formed on the upper wall 82, the incident wave W2 can be dissipated in the waveguide 80 in the form of heat while the electric wave is radiated from the feeding slot 61.

[0104] (9) Since the distance LL3 is formed such that the phase of the second reflected wave W3 is shifted from the phase of the first reflected wave W1, the second reflected wave W3 cancels out the first reflected wave W1. Therefore, the unwanted reflected wave can be reduced.

[0105] (10) When the distance LL3 is formed such that the phase of the second reflected wave W3 is opposite to the phase of the first reflected wave W1, the unwanted reflected wave can be minimized.

[0106] (11) By disposing the metal wall 75 and the partition wall 81 in the waveguide 80, the incident wave W2 enters the waveguide 80 surrounded by the two metal walls 75 and the two partition walls 81 from the passive slot 71. The incident wave W2 undergoes diffuse reflection on the metal wall 75 and the partition wall 81, so the heat loss amount of the incident wave W2 increases compared to the case where it is not surrounded by the metal wall 75, and the incident wave W2 can be further reduced. In addition, since the incident wave W2 undergoes diffuse reflection, the second reflected wave W3 generated by the diffuse reflection of the incident wave W2 is not easily returned to the passive slot 71, and the re-radiation of the second reflected wave W3 can be suppressed. Furthermore, the unwanted reflected wave can be further reduced.

[0107] <2-3. Second Embodiment>

[0108] Since the basic configuration of the second embodiment of the second implementation is the same as that of the first embodiment of the second implementation, the differences will be described below. In addition, the same reference numerals as those in the first embodiment of the second implementation denote the same configurations, and reference is made to the foregoing description.

[0109] As Figure 16 shown, the antenna device 10B of the second embodiment further has irregularities 76 on the inner surface of the waveguide 80. Thereby, the heat loss amount of the incident wave W2 can be increased. Furthermore, the unwanted reflected wave radiated from the antenna device 10B can be further suppressed.

[0110] (Other Embodiments)

[0111] As described above, embodiments of the present disclosure have been described, but the present disclosure is not limited to the above-described embodiments and can be implemented with various modifications.

[0112] (a) Although in the above-described first embodiment, each antenna element 21 is a radiation antenna element, it may also be a receiving antenna element. That is, each antenna element 21 can also receive the reflected wave generated by the reflection of radio waves on the target. In addition, although in the above-described second embodiment, each feeding slot 61 is a radiation antenna element, it may also be a receiving antenna element. That is, each feeding slot 61 can also receive the reflected wave generated by the reflection of radio waves on the target.

[0113] (b) Although in the above-described first embodiment, the antenna device 10A includes M antenna arrays 20, it may not include the antenna array 20. That is, the antenna device 10A may only include N passive arrays 30. Even so, the antenna device 10A can be used as a device for absorbing unnecessary radio waves.

[0114] (c) Although in the above-described first embodiment, the energy loss of radio waves in the second dielectric substrate 42 is greater than the energy loss of radio waves in the first dielectric substrate 41, they may also be the same. Even so, by adjusting the distance LL1 so that the phase of the second reflected wave W3 is offset from the phase of the first reflected wave W1, unnecessary reflected waves can be suppressed.

[0115] (d) Although in the above-described first embodiment, the distance LL1 is adjusted so that the phase of the second reflected wave W3 is offset from the phase of the first reflected wave W1, the distance LL1 can be any length. Even so, by making the energy loss of radio waves in the second dielectric substrate 42 greater than the energy loss of radio waves in the first dielectric substrate 41, the incident wave W2 can be dissipated in the second dielectric substrate 42 in the form of heat, suppressing unnecessary reflected waves.

[0116] (e) Although in the above-described second embodiment, the antenna device 10B includes M feeding slot arrays 60, it may not include the feeding slot array 60. That is, the antenna device 10B may only include N passive slot arrays 70. Even so, the antenna device 10B can be used as a device for absorbing unnecessary radio waves.

[0117] (f) Although in the above-described second embodiment, the energy loss of radio waves in the waveguide 80 is greater than the spatial attenuation, it may also be the same as the spatial attenuation. Even so, by adjusting the distance LL3 so that the phase of the second reflected wave W3 is offset from the phase of the first reflected wave W1, unnecessary reflected waves can be suppressed.

[0118] (g) Although in the above-described second embodiment, the distance LL3 is adjusted such that the phase of the second reflected wave W3 is shifted from the phase of the first reflected wave W1, the distance LL3 can be made of any length. Even so, by making the energy loss of the electric wave in the waveguide 80 larger than the spatial attenuation, the incident wave W2 can be dissipated in the waveguide 80 in the form of heat, suppressing unwanted reflected waves.

[0119] (h) Although in the above-described second embodiment apparatus, the antenna device 10B includes the metal wall 75, the metal wall 75 may not be provided. Even if the antenna device 10B does not include the metal wall 75, the incident wave W2 can be dissipated in the form of heat in the space partitioned by the partition wall 81.

[0120] (i) A plurality of functions of one component in the above-described embodiment may be implemented by a plurality of components, or one function of one component may be implemented by a plurality of components. In addition, a plurality of functions of a plurality of components may be implemented by one component, or one function implemented by a plurality of components may be implemented by one component. In addition, a part of the configuration of the above-described embodiment may be omitted. In addition, at least a part of the configuration of the above-described embodiment may be added to or replaced with the configuration of other above-described embodiments.

[0121] [Technical idea disclosed in this specification]

[0122] [Item 1] An electric wave absorption device, comprising:

[0123] A first dielectric substrate (41) having a first outer surface (41a) and a first inner surface (41b);

[0124] A second dielectric substrate (42) having a second outer surface (42a) and a second inner surface (42b);

[0125] A first conductor layer (53) provided with slits (58A, 58B) and configured to be in contact with the above-described first inner surface and the above-described second inner surface;

[0126] A passive element (31) disposed on the above-described first outer surface;

[0127] A second conductor layer (54) disposed on the above-described second outer surface; and

[0128] A metal wall (55) having a first end in contact with the above-described first conductor layer and a second end in contact with the above-described second conductor layer and penetrating the above-described second dielectric substrate,

[0129] The above-described metal wall is configured to shift the phase of the second reflected wave (W3) from the phase of the first reflected wave (W1). A part of the incident wave (W0) reaching the above-described first outer surface is reflected at at least one of the above-described passive element, the periphery of the above-described passive element, and the above-described first conductor layer to generate the above-described first reflected wave. Another part of the incident wave passes through the above-described passive element and the above-described slit and enters the above-described second dielectric substrate, and is reflected by the above-described metal wall to generate the above-described second reflected wave.

[0130] [Item 2] An electromagnetic wave absorption device, comprising:

[0131] A waveguide (80), which is a metal waveguide, having a first wall surface (82) provided with a first slit (71) that functions as a passive element, and a second wall surface (83) facing the above-described first wall surface; and

[0132] A metal wall (75, 81), having a first end in contact with the above-described first wall surface and a second end in contact with the above-described second wall surface, and partitioning the interior of the above-described waveguide.

[0133] The above-described metal wall is configured to shift the phase of the second reflected wave (W3) from the phase of the first reflected wave (W1). A part of the incident wave (W0) reaching the above-described first wall surface is reflected at the periphery of the above-described first slit to generate the above-described first reflected wave. Another part of the incident wave passes through the above-described first slit and enters the interior of the above-described waveguide, and is reflected by the above-described metal wall to generate the above-described second reflected wave.

[0134] [Item 3] The electromagnetic wave absorption device according to Item 1, wherein

[0135] In the direction along the above-described first dielectric substrate (41), the above-described metal wall (55) is disposed at a position at a predetermined distance (LL1) from the above-described slit (58A, 58B).

[0136] The above-described predetermined distance corresponds to a distance at which the phase of the above-described second reflected wave (W3) becomes a phase opposite to the phase of the above-described first reflected wave (W1).

[0137] [Item 4] The electromagnetic wave absorption device according to Item 2, wherein

[0138] In the direction along the above-described first wall surface (82), the above-described metal wall (75) is disposed at a position at a predetermined distance (LL3) from the above-described first slit (71).

[0139] The above-described predetermined distance corresponds to a distance at which the phase of the above-described second reflected wave (W3) becomes a phase opposite to the phase of the above-described first reflected wave (W1).

[0140] [Item 5] The radio wave absorption device according to Item 1 or 3, wherein,

[0141] It further includes an antenna element (21), which is arranged on the first outer surface (41a) and is configured to receive power supply to radiate radio waves or receive radio waves.

[0142] [Item 6] The radio wave absorption device according to Item 2 or 4, wherein,

[0143] A second slit (61) is further provided on the first wall surface (82), and the second slit (61) is configured to receive power supply to radiate radio waves or receive radio waves.

[0144] [Item 7] The radio wave absorption device according to any one of Items 1, 3, and 5, wherein,

[0145] The first end portion surrounds the slits (58A, 58B).

[0146] [Item 8] The radio wave absorption device according to any one of Items 1, 3, 5, and 7, wherein,

[0147] In the stacking direction of the first dielectric substrate (41) and the second dielectric substrate (42), the passive element (31) is arranged to overlap with the slits (58A, 58B).

[0148] [Item 9] The radio wave absorption device according to any one of Items 2, 4, and 6, wherein,

[0149] The first end portion surrounds the first slit (71).

[0150] [Item 10] The radio wave absorption device according to Item 3, wherein,

[0151] The specified distance is an odd multiple of one-fourth of the wavelength of the incoming wave.

Claims

1. An electromagnetic wave absorption device, wherein, Comprising: A first dielectric substrate (41) having a first outer surface (41a) and a first inner surface (41b); A second dielectric substrate (42) having a second outer surface (42a) and a second inner surface (42b); A first conductor layer (53) provided with slits (58A, 58B) and configured to be in contact with the first inner surface and the second inner surface; A passive element (31) disposed on the first outer surface; A second conductor layer (54) disposed on the second outer surface; And A metal wall (55) having a first end in contact with the first conductor layer and a second end in contact with the second conductor layer, the metal wall penetrating the second dielectric substrate, The metal wall is configured to shift the phase of the second reflected wave (W3) from the phase of the first reflected wave (W1). A part of the incoming wave (W0) reaching the first outer surface is reflected at at least one of the passive element, the periphery of the passive element, and the first conductor layer to generate the first reflected wave. Another part of the incoming wave enters the second dielectric substrate through the passive element and the slit, and is reflected by the metal wall to generate the second reflected wave.

2. An electromagnetic wave absorbing device, wherein, Comprising: A waveguide (80), which is a metal waveguide, having a first wall surface (82) provided with a first slit (71) acting as a passive element and a second wall surface (83) opposed to the first wall surface; and Metal walls (75, 81) having a first end in contact with the first wall surface and a second end in contact with the second wall surface, and the metal walls partition the interior of the waveguide, The metal walls are configured to shift the phase of the second reflected wave (W3) from the phase of the first reflected wave (W1). A part of the incoming wave (W0) reaching the first wall surface is reflected around the first slit to generate the first reflected wave. Another part of the incoming wave enters the interior of the waveguide through the first slit and is reflected by the metal walls to generate the second reflected wave.

3. The radio wave absorption device according to claim 1, wherein In the direction along the first dielectric substrate (41), the metal wall (55) is disposed at a position at a predetermined distance (LL1) from the slits (58A, 58B), The predetermined distance corresponds to a distance at which the phase of the second reflected wave (W3) becomes opposite to the phase of the first reflected wave (W1).

4. The radio wave absorption device according to claim 2, wherein In the direction along the first wall surface (82), the metal wall (75) is disposed at a position at a predetermined distance (LL3) from the first slit (71), The predetermined distance corresponds to a distance at which the phase of the second reflected wave (W3) becomes opposite to the phase of the first reflected wave (W1).

5. The radio wave absorption device according to claim 1, wherein An antenna element (21) is further provided, and the antenna element is disposed on the first outer surface (41a) and is configured to receive power supply to radiate radio waves or receive radio waves.

6. The radio wave absorption device according to claim 2, wherein: A second slit (61) is further provided on the first wall surface (82), and the second slit is configured to receive electric power to radiate radio waves or to receive radio waves.

7. The radio wave absorption device according to claim 1, wherein: The first end portion surrounds the slit (58A, 58B).

8. The radio wave absorption device according to claim 1, wherein: The passive element (31) is arranged to overlap the slits (58A, 58B) in a stacking direction of the first dielectric substrate (41) and the second dielectric substrate (42).

9. The radio wave absorption device according to claim 2, wherein: The first end portion surrounds the first slit (71).

10. The radio wave absorption device according to claim 3, wherein: The prescribed distance is an odd multiple of one quarter of the wavelength of the arrival wave.

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