Multi-mode millimeter wave substrate integrated waveguide cavity slot antenna array

Abstract

The invention discloses a multimode millimeter wave substrate integrated waveguide cavity slot antenna array, and relates to the technical field of communication antennas. The multimode millimeter wave substrate integrated waveguide cavity slot antenna array comprises an antenna substrate and a feed rectangular waveguide, wherein the antenna substrate comprises a first metal layer, a substrate and a second metal layer; the antenna substrate is provided with a plurality of metal via holes and a plurality of air via holes, and the first metal layer and the second metal layer are connected through the metal via holes so as to form a waveguide cavity in the antenna substrate; at least one radiation slot penetrating through the first metal layer is etched in the top surface of the antenna base body, and a feed slot penetrating through the second metal layer is etched in the bottom surface of the antenna base body; and the top surface of the feed rectangular waveguide is connected with the bottom surface of the second metal layer. By adopting the multimode millimeter wave substrate integrated waveguide cavity slot antenna array, the antenna structure can be simplified, and the antenna efficiency can be improved.

Description

Technical Field

[0001] The present invention relates to the technical field of communication antennas, and in particular to a multi-mode millimeter wave substrate integrated waveguide cavity slot antenna array. Background Art

[0002] Cavity-backed slot antennas are widely used in communication systems due to their high efficiency and high gain. Cavity-backed slot antennas are primarily designed using metal cavities and substrate integrated waveguides (SIWs). While metal cavities offer advantages such as low loss, high efficiency, and high power handling, their large size limits their application in modern communication systems. In contrast, SIW cavity-backed slot antennas offer the advantages of small size, light weight, and low cost.

[0003] Millimeter Wave (MMW) technology is one of the most promising solutions in the future wireless communication field. SIW structures have been widely used in the design of MMW slot antennas, especially MMW slot antenna arrays.

[0004] The existing SIW antennas are all based on SIW TE where the electric field is parallel to the metal vias. mn0 Moreover, the designed SIW slot antenna array usually requires a power divider, which makes the antenna structure complicated.

[0005] Therefore, it is urgent to design a multimode millimeter-wave substrate integrated waveguide cavity slot antenna array to solve the above problems. Summary of the Invention

[0006] The technical problem to be solved by the present invention is to provide a multimode millimeter wave substrate integrated waveguide cavity slot antenna array, which can simplify the antenna structure and improve the antenna efficiency.

[0007] In order to solve the above technical problems, the present invention provides a multimode millimeter wave substrate integrated waveguide cavity slot antenna array, comprising an antenna substrate and a feeding rectangular waveguide arranged below the antenna substrate, wherein the antenna substrate comprises a first metal layer, a substrate, and a second metal layer arranged in sequence from top to bottom;

[0008] The antenna base is provided with a plurality of metal vias and a plurality of air vias, both of which pass through the antenna base. The first metal layer and the second metal layer are connected through the metal vias to form a waveguide cavity in the antenna base, and the air vias are arranged around the periphery of the metal vias; the top surface of the antenna base is etched with at least one radiation slot passing through the first metal layer, and the bottom surface of the antenna base is etched with a feeding slot passing through the second metal layer; the top surface of the feeding rectangular waveguide is connected to the bottom surface of the second metal layer and is arranged around the periphery of the feeding slot.

[0009] As an improvement to the above scheme, the radiation gap is arranged on the top surface of the antenna base to form a radiation area; the metal vias are arranged at intervals and arranged around the periphery of the radiation area to form a metal ring; the air vias are arranged at intervals and arranged around the periphery of the metal ring to form an air ring.

[0010] As an improvement of the above solution, the metal ring is arranged on the periphery of the radiation zone to form a metal ring; the air ring is arranged on the periphery of the metal ring to form a first air ring and a second air ring, and the first air ring is arranged between the metal ring and the second air ring.

[0011] As an improvement to the above solution, N×M matrix-distributed radiation slots are provided in the radiation zone, where N and M are positive integers.

[0012] As an improvement of the above solution, when the multimode millimeter wave substrate integrated waveguide cavity slot antenna array works in TE 101 In the cavity mode, the relationship between the resonant frequency of the multi-mode millimeter wave substrate integrated waveguide cavity slot antenna array and the size of the waveguide cavity is:

[0013]

[0014] Among them, f TE101 The multimode millimeter wave substrate integrated waveguide cavity slot antenna array is in TE 101 The resonant frequency of the cavity mode, v is the speed of light in free space, a is the length of the waveguide cavity, c is the thickness of the waveguide cavity, ε r is the relative dielectric constant of the substrate.

[0015] As an improvement to the above solution, when the multimode millimeter wave substrate integrated waveguide cavity slot antenna array operates in the resonant window mode, the relationship between the resonant frequency of the multimode millimeter wave substrate integrated waveguide cavity slot antenna array and the waveguide cavity size, the radiation slot size, and the feeding slot size is:

[0016]

[0017] Among them, f iris is the resonant frequency of the multimode millimeter wave substrate integrated waveguide cavity slot antenna array in the resonant window mode, a is the length of the waveguide cavity, b is the width of the waveguide cavity, ε r is the relative dielectric constant of the substrate; when the radiation slot is single, L is the length of the radiation slot and the length of the feeding slot, and W is the width of the radiation slot and the width of the feeding slot; when the radiation slot is multiple and distributed in an array, L is the length of the feeding slot, and W is the width of the feeding slot.

[0018] As an improvement to the above solution, the substrate is made of Rogers RT5880, and the first metal layer and the second metal layer are made of copper.

[0019] As an improvement to the above solution, the thickness of the substrate is 3.175 mm, the dielectric constant is 2.18-2.22, the dissipation factor is 0.0009, and the thickness of the first metal layer and the second metal layer are both 0.017 mm.

[0020] As an improvement to the above solution, the horizontal cross-sections of the antenna substrate, the feeding rectangular waveguide, the radiation slot and the feeding slot are rectangular, and the horizontal cross-sections of the metal vias and the air vias are circular.

[0021] As an improvement to the above solution, the center of the metal via is set on the edge line of the waveguide cavity.

[0022] The beneficial effects of implementing the present invention are:

[0023] The multimode millimeter wave substrate integrated waveguide cavity slot antenna array of the present invention adopts the TE of waveguide cavity 101 mode to design the slot antenna, due to TE 101 The mode has an electric field distribution parallel to the radiation plane, which can directly excite multiple slots simultaneously. Therefore, the present invention does not require a power divider in traditional array antenna design, thereby simplifying the feeding structure of the slot antenna array;

[0024] At the same time, the multi-mode millimeter wave substrate integrated waveguide cavity slot antenna array of the present invention prevents energy leakage by adding the air via outside the metal via;

[0025] Furthermore, the multimode millimeter wave substrate integrated waveguide cavity slot antenna array of the present invention can 101 The combination of the cavity mode and the resonant window mode generated by the feeding slot enhances the bandwidth and improves the antenna efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1A perspective view of a first embodiment of a multi-mode millimeter-wave substrate integrated waveguide cavity slot antenna array according to the present invention;

[0027] Figure 2 A three-dimensional diagram of the first embodiment of the multi-mode millimeter-wave substrate integrated waveguide cavity slot antenna array according to the present invention from another angle;

[0028] Figure 3 A top view of a first embodiment of a multi-mode millimeter-wave substrate integrated waveguide cavity slot antenna array according to the present invention;

[0029] Figure 4 A bottom view of a first embodiment of a multi-mode millimeter-wave substrate integrated waveguide cavity slot antenna array according to the present invention;

[0030] Figure 5 The first embodiment of the multimode millimeter wave substrate integrated waveguide cavity slot antenna array of the present invention is in TE 101 Schematic diagram of cavity mode performance;

[0031] Figure 6 Schematic diagram of the performance of the first embodiment of the multi-mode millimeter-wave substrate integrated waveguide cavity slot antenna array in the resonant window mode of the present invention;

[0032] Figure 7 A perspective view of a second embodiment of a multi-mode millimeter-wave substrate integrated waveguide cavity slot antenna array according to the present invention;

[0033] Figure 8 A top view of a second embodiment of a multi-mode millimeter-wave substrate integrated waveguide cavity slot antenna array according to the present invention;

[0034] Figure 9 A bottom view of a second embodiment of a multi-mode millimeter-wave substrate integrated waveguide cavity slot antenna array according to the present invention;

[0035] Figure 10 This is a performance diagram of the second embodiment of the multi-mode millimeter wave substrate integrated waveguide cavity slot antenna array of the present invention. DETAILED DESCRIPTION

[0036] To make the objectives, technical solutions, and advantages of the present invention more apparent, the present invention will be further described in detail below with reference to the accompanying drawings. It is hereby stated that any directional terms such as "up," "down," "left," "right," "front," "back," "inside," and "outside" that appear or will appear herein are based solely on the accompanying drawings and are not intended to limit the present invention.

[0037] like Figures 1 to 4 As shown, Figures 1 to 4The specific structure of the first embodiment of the multi-mode millimeter-wave substrate-integrated waveguide cavity slot antenna array of the present invention is shown, including an antenna substrate 1 and a feeding rectangular waveguide 2 arranged below the antenna substrate. The antenna substrate 1 includes a first metal layer, a substrate, and a second metal layer arranged in sequence from top to bottom; the layered structure of the antenna substrate 1 achieves a compact design while ensuring good electromagnetic performance, can effectively isolate electromagnetic signals, and reduce signal loss.

[0038] The antenna base 1 is provided with a plurality of metal vias 12 and a plurality of air vias 13. The metal vias 12 and the air vias 13 both pass through the antenna base 1. The first metal layer and the second metal layer are connected through the metal vias 12 to form a waveguide cavity 11 in the antenna base 1. The air via ring 13 is provided on the periphery of the metal vias 12. In this embodiment, the antenna base 1 is provided with a plurality of metal vias and air vias. In actual applications, the number can be adjusted according to actual conditions.

[0039] The top surface of the antenna substrate 1 is etched with at least one radiation slot 111 penetrating the first metal layer, and the bottom surface of the antenna substrate 1 is etched with a feeding slot 14 penetrating the second metal layer. In this embodiment, there is only one radiation slot 111, but this is not limiting and can be set according to actual conditions.

[0040] The top surface of the feeding rectangular waveguide 2 is connected to the bottom surface of the second metal layer and is arranged around the periphery of the feeding slot 14. This structure can ensure efficient transmission of the signal at the feeding slot 14, reduce the impact of the feeding slot 14 on radiation performance, and optimize the overall performance.

[0041] It should be noted that the metal vias 12 connect the first and second metal layers, forming a waveguide cavity. This design effectively guides the propagation of electromagnetic waves, improving transmission efficiency and radiation performance. The air via rings, located around the metal vias, reduce signal loss during propagation, optimize electromagnetic field distribution, and increase the antenna's radiation gain and efficiency.

[0042] Therefore, the multimode millimeter wave substrate integrated waveguide cavity slot antenna array in this embodiment adopts the TE of the waveguide cavity. 101 mode to design the slot antenna, due to TE 101 The mode has an electric field distribution parallel to the radiation plane and can directly excite multiple slots simultaneously. Therefore, the present invention does not require a power divider in a traditional array antenna design, thereby simplifying the feeding structure of the slot antenna array.

[0043] Specifically, the radiation gap 111 is arranged on the top surface of the antenna base 1 to form a radiation area (not shown in the figure); the metal vias 12 are arranged at intervals and arranged around the periphery of the radiation area to form a metal ring; the air vias 13 are arranged at intervals and arranged around the periphery of the metal ring to form an air ring.

[0044] By arranging the radiation slot 111 on the top surface to form the radiation area, and arranging the metal ring and the air ring on the periphery of the radiation area, the radiation performance can be further enhanced, thereby improving the overall performance of the antenna.

[0045] Furthermore, the metal ring is arranged on the periphery of the radiation zone to form a metal ring; the air ring is arranged on the periphery of the metal ring to form a first air ring and a second air ring, and the first air ring is arranged between the metal ring and the second air ring.

[0046] From the inside to the outside, there are a metal ring, a first air ring and a second air ring, that is, the number of the metal ring is 1, and the number of the air rings is 2. Setting two air rings is more effective in preventing energy leakage than setting one air ring. However, too many air rings will increase the overall size, which is not conducive to the overall design.

[0047] Accordingly, this embodiment can work on TE 101 Cavity mode and resonant window mode, the following are the TE 101 The cavity mode and resonant window mode are described in detail:

[0048] 1. TE 101 Cavity Mode

[0049] When the multimode millimeter wave substrate integrated waveguide cavity slot antenna array works in TE 101 In the cavity mode, the relationship between the resonant frequency of the multi-mode millimeter wave substrate integrated waveguide cavity slot antenna array and the size of the waveguide cavity 11 is:

[0050]

[0051] in:

[0052] f TE101 The multimode millimeter wave substrate integrated waveguide cavity slot antenna array is in TE 101 The resonant frequency of the cavity mode;

[0053] v is the speed of light in free space;

[0054] a is the length of the waveguide cavity 11;

[0055] c is the thickness of the waveguide cavity 11 (i.e., the thickness of the antenna substrate 1);

[0056] ε r is the relative dielectric constant of the substrate.

[0057] Since the thickness of the waveguide cavity 11 is usually small, the TE 101 Cavity modes have higher resonant frequencies.

[0058] In practical applications, the length and thickness of the waveguide cavity can be set according to the resonant frequency, thereby achieving flexible setting of the resonant frequency.

[0059] like Figure 5 As shown, the present invention is applied to TE 101 In cavity mode, the impedance bandwidth (|S 11 The gain (|<-10dB) ranges from 27.87 GHz to 29.18 GHz (approximately 4.6%), with a peak gain of 6.18 dBi at 28.53 GHz. The simulated total efficiency at resonance (including impedance mismatch loss) is approximately 96.8%. This high efficiency indicates that energy leakage is negligible after the introduction of the air via 13.

[0060] 2. Resonant Window Mode

[0061] When the multimode millimeter wave substrate integrated waveguide cavity slot antenna array operates in the resonant window mode, the relationship between the resonant frequency of the multimode millimeter wave substrate integrated waveguide cavity slot antenna array and the size of the waveguide cavity 11, the size of the radiation slot 111 and the size of the feed slot 14 is:

[0062]

[0063] in:

[0064] f iris The resonant frequency of the multi-mode millimeter wave substrate integrated waveguide cavity slot antenna array in the resonant window mode;

[0065] a is the length of the waveguide cavity 11;

[0066] b is the width of the waveguide cavity 11;

[0067] ε r is the relative dielectric constant of the substrate;

[0068] When the radiation slot 111 is single, L is the length L1 of the radiation slot 111 and the length L of the feeding slot 14. s , W is the width W1 of the radiation slot 111 and the width W of the feed slot 14 S ;

[0069] When the radiation slots 111 are multiple and distributed in an array, L is the length L of the feeding slot 14.s , W is the width W of the feed slot 14 S .

[0070] It should be noted that when designing a multimode millimeter-wave substrate integrated waveguide cavity slot antenna array, the sizes of the radiation slot and the feeding slot have an impact on the resonant frequency of the antenna.

[0071] The dielectric constant is an inherent property of a material, while the relative permittivity describes the material's dielectric properties relative to a vacuum. The relative permittivity describes a material's ability to polarize under an electric field, or its ability to store charge. The larger the relative permittivity, the greater the material's ability to store electrical energy.

[0072] The relationship between dielectric constant and relative permittivity is as follows:

[0073] ε r =ε / ε0

[0074] in:

[0075] ε r is the relative dielectric constant;

[0076] ε is the dielectric constant;

[0077] ε0 is the vacuum dielectric constant, which is a basic physical constant that indicates the response of a vacuum (an ideal space without any substance) to an electric field. The value of the vacuum dielectric constant is: ε0 = 8.854187817 × 10 - 12 F / m.

[0078] In practical applications, the length and width of the waveguide cavity and the feeding slot can be set according to the resonant frequency, thereby achieving flexible setting of the resonant frequency.

[0079] like Figure 6 As shown, when the present invention is applied to the resonant window mode, there are two resonant frequencies at 22.9 GHz and 24.65 GHz respectively, and the impedance bandwidth (|S 11 |<-10dB) is 22.54GHz to 25.07GHz (about 10.7%), with an in-band gain higher than 5.8dBi, a peak gain of 6.3dBi, and a total efficiency exceeding 90%.

[0080] Comprehensive, TE 101 It can be seen from the performance of the cavity mode and the resonant window mode that the multi-mode millimeter wave substrate integrated waveguide cavity slot antenna array of the present invention can prevent energy leakage by adding the air via 13 outside the metal via 12.

[0081] Furthermore, regarding material selection, the substrate is preferably made of Rogers RT5880, and the first and second metal layers are made of copper. Using Rogers RT5880 for the substrate and copper for the first and second metal layers ensures excellent dielectric and electrical properties, reduces signal transmission loss, improves antenna efficiency and reliability, and ensures stable operation in the millimeter wave band.

[0082] In order to further optimize the performance, ensure lower insertion loss and higher radiation efficiency within the design frequency band, and improve processing accuracy and consistency to meet the requirements of high-performance millimeter-wave antennas, preferably, the thickness of the substrate is 3.175 mm, the dielectric constant is 2.18-2.22, the dissipation factor is 0.0009, and the thickness of the first metal and the second metal layer are both 0.017 mm (because the thickness of the first metal and the second metal layer is smaller than the thickness of the substrate, the substrate, the first metal layer and the second metal layer are not marked separately in the figure, and only the antenna base 1 is marked).

[0083] Regarding the specific shape of the multi-mode millimeter-wave substrate-integrated waveguide cavity slot antenna array of the present invention, the antenna substrate 1, feed rectangular waveguide 2, radiation slot 111, and feed slot 14 have rectangular horizontal cross-sections, while the metal vias 12 and air vias 13 have circular horizontal cross-sections. This structural design simplifies the manufacturing process, improves production efficiency, and better controls the distribution of the electromagnetic field, ensuring performance stability.

[0084] like Figure 3 As shown, the center of the metal via 12 is located on the edge of the waveguide cavity 11. On a plane, the center of the metal via 12 is located on the length and width edges of the waveguide cavity 11. Placing the center of the metal via 12 on the edge of the waveguide cavity 11 can further optimize electromagnetic field coupling and transmission, improve radiation efficiency and bandwidth, enhance structural stability, and reduce the impact of manufacturing errors.

[0085] In addition, regarding the number and distribution of the radiation slots 111, the radiation area is provided with N×M matrix-distributed radiation slots, where N and M are positive integers. The use of the matrix-distributed radiation slots 111 can achieve a more uniform radiation field distribution, improve gain and directivity, and facilitate flexible adjustment of the radiation direction and beam width to meet different communication requirements.

[0086] For example, the distribution mode of 2×2, 3×3, 4×4, 5×5, 6×6, etc. is adopted, but it is not limited to this and can be set according to the actual situation;

[0087] For another example, a distribution method of 1×2, 2×3, 3×4... is adopted, but it is not limited to this and can be set according to actual conditions.

[0088] like Figures 7 to 9 As shown, Figures 7 to 9 The second embodiment of the multi-mode millimeter wave substrate integrated waveguide cavity slot antenna array of the present invention is shown. Different from the first embodiment, in this embodiment, the number of the radiation slots 111 is 16 and they are distributed in an array in the form of 4 rows and 4 columns.

[0089] like Figure 8 As shown, from the overall structure, in order to simplify the design and improve the system compatibility, the multi-mode millimeter wave substrate integrated waveguide cavity slot antenna array is symmetrical about its central plane A and central plane B;

[0090] In order to improve adaptability and flexibility, the lengths L1, L2, L3 and L4 of the radiation slot 111, the widths W1, W2, W3 and W4 of the radiation slot 111, and the length L of the feed slot 14 are S , the width W of the feed slot 14 S The x-axis center distances D1 and D2 of adjacent radiation slots 111 and the y-axis center distances D3 and D4 of adjacent radiation slots 111 can be designed according to specific application conditions to achieve different performance requirements and better adapt to various working conditions.

[0091] The plurality of radiation slots 111 can improve radiation gain, and the radiation slots 111 can be directly excited by their electric field distribution without introducing an additional power distribution network.

[0092] like Figure 10 As shown, the impedance bandwidth (|S 11 |<-10dB) from 25.16GHz to 26.88GHz (about 6.6%), with a peak gain of 15.6dBi at 26.3GHz and an overall efficiency exceeding 90%.

[0093] In summary, the multimode millimeter wave substrate integrated waveguide cavity slot antenna array of the present invention can 101 The combination of the cavity mode and the resonant window mode generated by the feeding slot enhances the bandwidth and improves the antenna efficiency.

[0094] The above is a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principles of the present invention. These improvements and modifications are also considered to be within the scope of protection of the present invention.

Claims

1. A multimode millimeter wave substrate integrated waveguide cavity slot antenna array, characterized in that: It includes an antenna base and a feeding rectangular waveguide arranged below the antenna base, wherein the antenna base includes a first metal layer, a substrate and a second metal layer arranged in sequence from top to bottom; The antenna substrate is provided with a plurality of metal vias and a plurality of air vias, both of which penetrate the antenna substrate, and the first metal layer and the second metal layer are connected through the metal vias to form a waveguide cavity in the antenna substrate, and the air via ring is provided on the periphery of the metal vias; At least one radiation slot penetrating the first metal layer is etched on the top surface of the antenna substrate, and a feeding slot penetrating the second metal layer is etched on the bottom surface of the antenna substrate; The top surface of the feeding rectangular waveguide is connected to the bottom surface of the second metal layer and is arranged around the periphery of the feeding gap.

2. The multimode millimeter wave substrate integrated waveguide cavity slot antenna array according to claim 1, characterized in that: The radiation slot is provided on the top surface of the antenna substrate to form a radiation area; The metal vias are arranged at intervals and arranged around the periphery of the radiation area to form a metal ring; The air holes are arranged at intervals and arranged around the periphery of the metal ring to form an air ring.

3. The multimode millimeter wave substrate integrated waveguide cavity slot antenna array according to claim 2, characterized in that: The metal ring is arranged on the periphery of the radiation zone to form a metal ring; The air ring is arranged on the periphery of the metal ring to form a first air ring and a second air ring, and the first air ring is arranged between the metal ring and the second air ring.

4. The multimode millimeter wave substrate integrated waveguide cavity slot antenna array according to claim 2, characterized in that: The radiation zone is provided with N×M radiation slots distributed in a matrix, wherein N and M are positive integers.

5. The multimode millimeter wave substrate integrated waveguide cavity slot antenna array according to claim 1, characterized in that: When the multimode millimeter wave substrate integrated waveguide cavity slot antenna array works in TE 101 In the cavity mode, the relationship between the resonant frequency of the multi-mode millimeter wave substrate integrated waveguide cavity slot antenna array and the size of the waveguide cavity is: Among them, f TE101 The multimode millimeter wave substrate integrated waveguide cavity slot antenna array is in TE 101 The resonant frequency of the cavity mode, v is the speed of light in free space, a is the length of the waveguide cavity, c is the thickness of the waveguide cavity, ε r is the relative dielectric constant of the substrate.

6. The multimode millimeter wave substrate integrated waveguide cavity slot antenna array according to claim 1, characterized in that: When the multimode millimeter wave substrate integrated waveguide cavity slot antenna array operates in the resonant window mode, the relationship between the resonant frequency of the multimode millimeter wave substrate integrated waveguide cavity slot antenna array and the waveguide cavity size, radiation slot size, and feeding slot size is: Among them, f iris is the resonant frequency of the multimode millimeter wave substrate integrated waveguide cavity slot antenna array in the resonant window mode, a is the length of the waveguide cavity, b is the width of the waveguide cavity, ε r is the relative dielectric constant of the substrate; When the radiation slot is single, L is the length of the radiation slot and the length of the feeding slot, and W is the width of the radiation slot and the width of the feeding slot; When there are multiple radiation slots and they are distributed in an array, L is the length of the feeding slot, and W is the width of the feeding slot.

7. The multimode millimeter wave substrate integrated waveguide cavity slot antenna array according to claim 1, characterized in that: The substrate is made of Rogers RT5880, and the first metal and second metal layers are made of copper.

8. The multimode millimeter wave substrate integrated waveguide cavity slot antenna array according to claim 1, characterized in that: The thickness of the substrate is 3.175 mm, the dielectric constant is 2.18-2.22, the dissipation factor is 0.0009, and the thickness of the first metal layer and the second metal layer are both 0.017 mm.

9. The multimode millimeter wave substrate integrated waveguide cavity slot antenna array according to claim 1, characterized in that: The horizontal cross-sections of the antenna substrate, the feeding rectangular waveguide, the radiation slot and the feeding slot are rectangular, and the horizontal cross-sections of the metal vias and the air vias are circular.

10. The multimode millimeter wave substrate integrated waveguide cavity slot antenna array according to claim 9, characterized in that: The center of the metal via is arranged on the edge line of the waveguide cavity.

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