Waveguide antenna structure and radar

Abstract

This invention discloses a waveguide antenna structure and radar, relating to the field of waveguide antennas. The antenna structure includes a first substrate and a second substrate, with a waveguide cavity formed by a first waveguide channel on the bottom surface of the first substrate and a second waveguide channel on the top surface of the second substrate. Multiple rows of radiating slots are provided on the top surface of the first substrate, each row communicating with a corresponding first waveguide channel. The radiating slots include first radiating slots and second radiating slots. Each group of first radiating slots includes two rows of first radiating slots, with a first metal ridge between adjacent groups of first radiating slots and a second metal ridge outside the outermost row of first radiating slots. A third metal ridge is provided between adjacent rows of second radiating slots, and a fourth metal ridge outside the outermost row of second radiating slots. This invention widens the antenna beamwidth, stabilizes the beam, and facilitates a larger detection range for the radar.

Description

Technical Field

[0001] This invention belongs to the field of waveguide antenna technology, and particularly relates to a waveguide antenna structure and radar. Background Technology

[0002] Compared to microstrip antennas, waveguide antennas have very low losses due to the absence of dielectric loss, resulting in higher efficiency, especially when the antenna array is large and the feed line is long. Common types of waveguide antennas include SIW (Substrate Integrated Waveguide) slot antennas, gap waveguide antennas, and rectangular waveguide slot antennas, which can be used to receive or transmit electromagnetic waves.

[0003] In common waveguide slot antenna designs, radiation is typically achieved by creating a slot in the H-plane (wide side) of the waveguide. Currently, automotive millimeter-wave radar chips often employ a LOP (Launch On Package) structure, where the chip and waveguide antenna are directly connected via waveguide ports, eliminating the need for PCB adapters. Since the distance between the various waveguide ports on the chip is generally short, to achieve more compact routing and meet manufacturing requirements (waveguide transmission line spacing greater than 1mm), the antenna is typically connected to each chip via transmission lines on the E-plane (narrow side) of the waveguide. If the antenna uses an H-plane slot for radiation, the waveguide cavity will have two sections with inconsistent heights. Therefore, during current waveguide antenna manufacturing, it is best to cut the waveguide cavity in half lengthwise for layered processing to better ensure no energy leakage after assembly. If the heights of the two waveguide cavities are not consistent, it is not conducive to cutting both waveguide cavities in half and layering them. Therefore, the method of using the waveguide E-plane slot for radiation in millimeter-wave radar antennas is more conducive to the compactness of the antenna structure and the yield rate of the manufactured antenna.

[0004] In the antenna feeding design, a section of the waveguide H-plane is directly connected to the waveguide E-plane cavity. To ensure the simplicity and ease of fabrication of the overall structure and the symmetry of the cavity height and length, no matching adjustment structures are added, resulting in limited bandwidth and an inability to cover the entire 76GHz–81GHz frequency range defined for automotive radar. In the field of automotive radar, although metal-plastic composite processing technology has reduced the manufacturing cost of rectangular waveguide antennas and offers advantages such as large bandwidth, high power capacity, low loss, and high efficiency, manufacturers often require rounded corners at certain locations, resulting in semi-circular waveguide ends that affect antenna matching.

[0005] Patent document CN118610743A discloses an E-plane waveguide antenna structure. Its electromagnetic bandgap structure utilizes a high-impedance surface formed by periodic metal pillars, which prevents electromagnetic waves from propagating in that direction, thus confining the electromagnetic waves. This results in a narrow azimuth beamwidth for the antenna, making it unsuitable for radar systems that require large-angle detection. In order to change the phase of the cavity and the amplitude distribution of each slot, and reduce sidelobes, waveguide sections and steps are added between the radiation slots. This makes the waveguide cavity less symmetrical, the structure more complex, and increases the difficulty of manufacturing.

[0006] The patent document with application publication number CN115566400A discloses a 3D metallized vehicle-mounted millimeter-wave radar antenna. Its feeding cavity structure is too complex to be applied to metal-plastic processing or to achieve double-layer processing.

[0007] Antennas are the eyes of radar systems. Some radars (such as corner radars) require extremely wide detection ranges, which necessitates antennas with wide beam patterns. Wide-beam designs are not common in current waveguide antenna designs. To improve radar detection range, and specifically for wide-beam antenna applications in automotive radar, a wide-beam, simple, and easily fabricated double-layer waveguide antenna needs to be designed. Summary of the Invention

[0008] The purpose of this invention is to provide a waveguide antenna structure and radar to solve at least one of the following problems: the narrow beamwidth of traditional antenna structures makes them unsuitable for radar systems with large-angle detection, and the asymmetrical cavity structure leads to structural complexity and increased manufacturing difficulty.

[0009] The present invention solves the above-mentioned technical problems through the following technical solution: a waveguide antenna structure, comprising a first substrate and a second substrate stacked together, wherein a plurality of first waveguide channels are provided on the bottom surface of the first substrate, and a plurality of second waveguide channels are provided on the top surface of the second substrate, wherein the first waveguide channels and the second waveguide channels correspond one-to-one and have the same structural dimensions, and a waveguide cavity is formed by the corresponding and connected first waveguide channels and second waveguide channels; a plurality of rows of radiating slots are provided on the top surface of the first substrate, wherein each row of radiating slots corresponds to a first waveguide channel and is connected to the corresponding first waveguide channel; the radiating slots include first radiating slots and second radiating slots, wherein each row of first radiating slots corresponds to a receiving antenna assembly, and each row of second radiating slots corresponds to a transmitting antenna assembly;

[0010] Each group of first radial slots includes two rows of first radial slots, with a first metal ridge between two adjacent groups of first radial slots, and a second metal ridge on the outside of the outermost row of first radial slots; a third metal ridge between two adjacent rows of second radial slots, and a fourth metal ridge on the outside of the outermost row of second radial slots.

[0011] Compared to electromagnetic bandgap structures, metal ridges are simpler and easier to manufacture. Furthermore, metal ridges can reflect the spatial electric field of the antenna azimuth plane, reducing the antenna normal gain and widening the antenna beamwidth. The first and second waveguide channels of this invention have the same and symmetrical dimensions, which facilitates the use of metal-plastic processing technology. This is beneficial for low-cost antenna manufacturing, improving the yield of finished antenna products, and reducing electromagnetic wave leakage in the waveguide cavity after processing.

[0012] Furthermore, the sum of the heights of the first waveguide channel and the second waveguide channel is 2.8 mm to 3.4 mm, and the widths of both the first and second waveguide channels are 1 mm to 1.4 mm.

[0013] Furthermore, the height of the first, second, third, and fourth metal ridges is 0.5mm to 1mm, and the width is 0.5mm to 1mm; the center distance between adjacent second radiating slots and the third metal ridge, and the center distance between adjacent second radiating slots and the fourth metal ridge are both 0.75 times the air wavelength corresponding to the antenna center frequency; the center distance between adjacent first radiating slots and the first metal ridge, and the center distance between adjacent first radiating slots and the second metal ridge are both 0.75 times the air wavelength corresponding to the antenna center frequency.

[0014] Furthermore, the number of first metal ridges between two adjacent sets of first radiation slots, the number of second metal ridges outside the outermost row of first radiation slots, and the number of fourth metal ridges outside the outermost row of second radiation slots are all 2. The number of third metal ridges between two adjacent rows of second radiation slots is 1. The center distance between two adjacent fourth metal ridges is 1.5 times the air wavelength corresponding to the antenna center frequency, and the center distance between two adjacent second metal ridges is 1 time the air wavelength corresponding to the antenna center frequency.

[0015] Furthermore, relative to the other rows of second radiating slots, the rightmost row of second radiating slots moves upward by a distance equal to 0.5 times the air wavelength corresponding to the antenna center frequency; the center distance between the two nearest rows of second radiating slots is 1.5 times the air wavelength corresponding to the antenna center frequency; and the center distance between the nearest third and fourth metal ridges is 1.5 times the air wavelength corresponding to the antenna center frequency.

[0016] Furthermore, the center distance between the two rows of first radiating slots in each group is 1 times the air wavelength corresponding to the antenna center frequency, and the center distance between the two nearest groups of first radiating slots is 3.5 times the air wavelength corresponding to the antenna center frequency.

[0017] Furthermore, for each row of first and second radiating slots, the width of each radiating slot is greater than 1 mm and less than 2 mm, the height of each radiating slot is 1 mm to 1.5 mm, the length of each radiating slot is 2 mm to 2.3 mm, and the width of the two radiating slots on both sides is less than the width of the middle radiating slot, and the center-to-center distance between two adjacent radiating slots is less than 1 times the air wavelength corresponding to the antenna center frequency.

[0018] Furthermore, for the first radial slit in each row and the second radial slit in each row, the inner corner of each radial slit is rounded with a radius of 0.5mm.

[0019] Furthermore, each first waveguide channel and each second waveguide channel includes a feeding cavity and a connecting cavity, and the first end of the connecting cavity is connected to the feeding cavity through a transition section.

[0020] Preferably, the first end of the connecting cavity of the second waveguide channel is provided with a protrusion, the protrusion is flush with the transition section, and the length of the protrusion is greater than the length of the transition section; an interface is provided on the bottom surface of the second substrate, and a groove is provided at the second end of the connecting cavity of the second waveguide channel, the groove communicating with the interface.

[0021] Based on the same concept, the present invention also provides a radar comprising the waveguide antenna structure described above.

[0022] Beneficial effects

[0023] Compared with the prior art, the advantages of the present invention are as follows:

[0024] This invention incorporates a metal ridge around the radiating slot. This ridge reflects the spatial electric field of the antenna's azimuth plane. The energy excited by the reflected wave is out of phase with the antenna's energy, resulting in weaker energy at the 0° position and stronger energy in the surrounding area. This increases the antenna beamwidth, stabilizes the beam, and facilitates a wider detection range for the radar. Furthermore, compared to electromagnetic bandgap structures, the metal ridge structure is simpler and easier to manufacture. The first and second waveguide channels have the same and symmetrical dimensions, allowing for the antenna structure to be cut in half and processed in a double-layer manner. This approach is beneficial for low-cost antenna manufacturing, improving the yield rate of finished antenna products, and reducing electromagnetic wave leakage within the waveguide cavity after processing.

[0025] The position of the row of radiating slots corresponding to the rightmost transmitting antenna (i.e., the second radiating slot in the rightmost row) is moved upward, and every two rows of the first radiating slots are grouped together. A first metal ridge is provided between each group of the first radiating slots, so that the radar can measure the height of the elevation plane. Attached Figure Description

[0026] To more clearly illustrate the technical solution of the present invention, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only one embodiment of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0027] Figure 1 This is a top-down exploded view of the waveguide antenna structure in an embodiment of the present invention;

[0028] Figure 2 This is a bottom-view exploded view of the waveguide antenna structure in an embodiment of the present invention;

[0029] Figure 3 This is a top view of the waveguide antenna structure in an embodiment of the present invention;

[0030] Figure 4 This is a schematic diagram of the waveguide cavity and radiation gap (the part that needs to be removed during processing) in an embodiment of the present invention;

[0031] Figure 5 This is a schematic diagram of the waveguide cavity and radiation slot (the part that needs to be removed during processing) of a single antenna in an embodiment of the present invention;

[0032] Figure 6 This is a schematic diagram showing the position and size of the radial slit and the metal ridge in an embodiment of the present invention;

[0033] Figure 7 This is a schematic diagram showing the dimensions of a single row of first radial slits or a single row of second radial slits in an embodiment of the present invention.

[0034] Figure 8 This is a schematic diagram of the transition section of the first waveguide channel in an embodiment of the present invention;

[0035] Figure 9 This is a schematic diagram of the transition section of the second waveguide channel in an embodiment of the present invention;

[0036] Figure 10 This is the azimuth pattern of the transmitting antenna in this embodiment of the invention;

[0037] Figure 11 This is the azimuth pattern of the receiving antenna in this embodiment of the invention;

[0038] Figure 12 This is the antenna reflection coefficient curve in an embodiment of the present invention;

[0039] Figure 13 This is the elevation pattern of the transmitting antenna in this embodiment of the invention;

[0040] Figure 14 This is the elevation plane pattern of the receiving antenna in this embodiment of the invention.

[0041] Explanation of reference numerals in the attached drawings: 100-First substrate, 101-Second radiating slot, 102-Third metal ridge, 103-Fourth metal ridge, 104-First radiating slot, 105-Second metal ridge, 106-First metal ridge, 107-First waveguide channel, 200-Second substrate, 201-Second waveguide channel, 202-Connecting cavity, 203-Feeding cavity, 204-Transition section, 205-Adapter, 206-Protrusion, 301-Part of the connecting cavity to be removed during processing, 302-Part of the feeding cavity to be removed during processing, 303-Part of the radiating slot to be removed during processing, 304-Fillet corner treatment effect of the inner corner of the feeding cavity, 305-Part of the transition section to be removed during processing, 306-Part of the first end of the connecting cavity to be removed during processing, 307-Part of the second end of the connecting cavity to be removed during processing. Detailed Implementation

[0042] The technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0043] The technical solutions of this application will be described in detail below with specific embodiments. The following specific embodiments can be combined with each other, and the same or similar concepts or processes may not be described again in some embodiments.

[0044] This invention uses an example of four transmitting antennas and four receiving antennas to illustrate the waveguide antenna structure. For example... Figures 1 to 5As shown, the waveguide antenna structure provided in this embodiment of the invention includes a first substrate 100 and a second substrate 200 stacked together. Eight first waveguide channels 107 are provided on the bottom surface of the first substrate 100, and eight second waveguide channels 201 are provided on the top surface of the second substrate 200. The first waveguide channels 107 and the second waveguide channels 201 correspond one-to-one and have the same structural dimensions. A waveguide cavity is formed by the corresponding and connected first waveguide channels 107 and second waveguide channels 201. Eight rows of radiating slots are provided on the top surface of the first substrate 100, each row of radiating slots corresponding to and connected to one first waveguide channel 107. The eight rows of radiating slots include four rows of first radiating slots 104 and four rows of second radiating slots 101. The four rows of first radiating slots 104 correspond to four receiving antenna components, and the four rows of second radiating slots... Each slot 101 corresponds to one of the four transmitting antenna assemblies. Each group of first radiating slots 104 includes two rows of first radiating slots 104. A first metal ridge 106 is provided between two adjacent groups of first radiating slots 104. A second metal ridge 105 is provided on the outer side of the outermost row of first radiating slots 104, that is, a second metal ridge 105 is provided on the outer side of the leftmost row of first radiating slots 104 and on the outer side of the rightmost row of first radiating slots 104. A third metal ridge 102 is provided between two adjacent rows of second radiating slots 101. A fourth metal ridge 103 is provided on the outer side of the outermost row of second radiating slots 101, that is, a fourth metal ridge 103 is provided on the outer side of the leftmost row of second radiating slots 101 and on the outer side of the rightmost row of second radiating slots 101.

[0045] Metal ridges are added on both sides of the radiation slot. These ridges reflect the spatial electric field of the antenna azimuth plane. The energy excited by the reflected wave is out of phase with the energy of the antenna, making the energy at the 0° position of the antenna weaker and the energy around it stronger. This increases the antenna beamwidth, stabilizes the beam, and helps the radar achieve a larger detection range. To meet the requirements of plastic metallization processing and reduce electromagnetic wave leakage in the waveguide cavity after processing, the first waveguide channel 107 and the second waveguide channel 201 have identical and symmetrical structures and dimensions. The waveguide antenna structure of this invention is relatively simple, can be processed in two layers, has low processing cost, is easy to assemble, and has a high yield rate.

[0046] Because the spacing between the two rows of first radiating slots 104 in each group is small, setting a metal ridge between these two rows of first radiating slots 104 would affect antenna matching and compress the antenna azimuth pattern. Therefore, no metal ridge is set between the two rows of first radiating slots 104 in each group. A third metal ridge 102 is added between the two rows of second radiating slots 101 to ensure the consistency of the antenna pattern.

[0047] In a specific embodiment of the present invention, the sum of the height of the first waveguide channel 107 and the height of the second waveguide channel 201 is 2.8mm to 3.4mm, and the widths of both the first waveguide channel 107 and the second waveguide channel 201 are 1mm (to meet processing requirements) to 1.4mm. Preferably, the sum of the heights of the first waveguide channel 107 and the second waveguide channel 201 is 3.2mm, and the widths of both the first waveguide channel 107 and the second waveguide channel 201 are preferably 1mm. Setting the width to 1mm is the minimum processing requirement; a lower width facilitates the design of antennas with equal line lengths (in phase).

[0048] In a specific embodiment of the present invention, the height of the first metal ridge 106, the second metal ridge 105, the third metal ridge 102, and the fourth metal ridge 103 is 0.5mm to 1mm, and the width is 0.5mm to 1mm; the center distance between adjacent second radiation slots 101 and third metal ridges 102, and between adjacent second radiation slots 101 and fourth metal ridges 103, are both 0.75 times the air wavelength corresponding to the antenna center frequency; the center distance between adjacent first radiation slots 104 and first metal ridges 106, and between adjacent first radiation slots 104 and second metal ridges 105, are both 0.75 times the air wavelength corresponding to the antenna center frequency. Preferably, the height of the first metal ridge 106, second metal ridge 105, third metal ridge 102, and fourth metal ridge 103 is 0.5mm, and the width is 0.8mm.

[0049] For example, if the air wavelength corresponding to the antenna center frequency of 78 GHz is approximately 3.8 mm, then the center distance between adjacent second radiating slots 101 and third metal ridges 102 is 2.85 mm, the center distance between adjacent second radiating slots 101 and fourth metal ridges 103 is 2.85 mm, the center distance between adjacent first radiating slots 104 and first metal ridges 106 is 2.85 mm, and the center distance between adjacent first radiating slots 104 and second metal ridges 105 is 2.85 mm. Figure 6 As shown.

[0050] The purpose of the metal ridges is to widen the antenna's azimuth beamwidth and stabilize the beam. The metal ridges reflect a portion of the surface waves. Different heights and positions of the metal ridges control the phase of the reflected waves. When the energy excited by the reflected wave is out of phase with the antenna's energy, the energy at the 0° position of the antenna weakens, while the energy in the surrounding areas strengthens, thus widening the antenna's beamwidth. By optimizing the design to determine the height, width, and position of each metal ridge, the antenna beamwidth was widened from 6dB to 190°, significantly increasing the radar's detection range.

[0051] In a specific embodiment of the present invention, the number of first metal ridges 106 between two adjacent sets of first radial slits, the number of second metal ridges 105 outside the outermost row of first radial slits (including the leftmost and rightmost slits), and the number of fourth metal ridges 103 outside the outermost row of second radial slits (including the leftmost and rightmost slits) are all 2, and the number of third metal ridges 102 between two adjacent rows of second radial slits is 1. Figure 3 As shown. The center distance between two adjacent fourth metal ridges 103 is 1.5 times the air wavelength corresponding to the antenna center frequency, and the center distance between two adjacent second metal ridges 105 is 1 time the air wavelength corresponding to the antenna center frequency. The two outermost metal ridges of the radiation slots (i.e., the two second metal ridges 105 respectively set on the left and right sides of the first radiation slot 104 and the two fourth metal ridges 103 respectively set on the left and right sides of the second radiation slot 101) are beneficial to improving the antenna beamwidth and also to improving the stability of the antenna beam at different positions.

[0052] For example, if the air wavelength corresponding to the antenna center frequency of 78 GHz is approximately 3.8 mm, then the center distance between the two fourth metal ridges 103 is 5.7 mm, and the center distance between the two second metal ridges 105 is 3.8 mm. Figure 6 As shown. In order to balance the azimuth pattern of the antenna as much as possible, the center distance between the two second metal ridges 105 is adjusted. When the center distance between the two second metal ridges 105 is 1 times the air wavelength corresponding to the center frequency of the antenna, the azimuth pattern of the antenna is balanced.

[0053] In order for the radar to measure the elevation plane, relative to the other rows of second radiation slots 101, the rightmost row of second radiation slots 101 is moved upward (upward means towards the direction of the first radiation slot 101) by a distance equal to 0.5 times the air wavelength corresponding to the antenna center frequency; the center distance between the two nearest rows of second radiation slots 101 is 1.5 times the air wavelength corresponding to the antenna center frequency; and the center distance between the nearest third metal ridge 102 and fourth metal ridge 103 is 1.5 times the air wavelength corresponding to the antenna center frequency.

[0054] For example, if the air wavelength corresponding to the antenna center frequency of 78 GHz is approximately 3.8 mm, then the distance by which the rightmost row of second radiating slots 101 moves upward is 1.9 mm; the center distance between the two nearest rows of second radiating slots 101 is 5.7 mm; the center distance between the nearest third metal ridge 102 and fourth metal ridge 103 is 5.7 mm, and so on. Figure 6 As shown.

[0055] In a specific embodiment of the present invention, the center distance between the two rows of first radiating slots 104 in each group is 1 times the air wavelength corresponding to the antenna center frequency, the center distance between the two nearest groups of first radiating slots 104 is 3.5 times the air wavelength corresponding to the antenna center frequency, and the center distance between the nearest row of first radiating slots 104 and the second metal ridge 105 is 0.75 times the air wavelength corresponding to the antenna center frequency.

[0056] For example, if the air wavelength corresponding to the antenna center frequency of 78 GHz is approximately 3.8 mm, then the center-to-center distance between the two rows of first radiating slots 104 in each group is 3.8 mm, and the center-to-center distance between the two nearest groups of first radiating slots 104 is 13.3 mm. Figure 6 As shown.

[0057] The structure of each transceiver antenna (i.e., the size and length of the radiating slot and the size of the waveguide cavity) is completely identical. In order to meet the requirements of antenna plastic metallization processing, the width of the metal layer between the antennas is 1mm, and the inner corner of each radiating slot is rounded by 0.5mm. The width of the radiating slot is greater than 1mm.

[0058] In a specific embodiment of the present invention, for each row of first radial slits 104 and each row of second radial slits 101, each radial slit (e.g. Figure 4 and Figure 5 The width of 303 is greater than 1 mm and less than 2 mm. The height of each radiating slit is 1 mm to 1.5 mm, the length of each radiating slit is 2 mm to 2.3 mm, and the width of the two radiating slits on both sides is less than the width of the middle radiating slit. The center-to-center distance between two adjacent radiating slits is less than 1 times the air wavelength corresponding to the center frequency of the antenna and greater than the length of the radiating slit + 1 mm (meeting the processing requirements).

[0059] In this embodiment, in each row of first radial slits 104 or each row of second radial slits 101, such as Figure 7 As shown, the width of the radiating slots on both sides is preferably 1.4 mm, and the width of the two middle radiating slots is preferably 1.7 mm. Increasing the width of the radiating slots facilitates the antenna's matching with free space over a wide frequency band, thus improving the antenna's bandwidth. In this embodiment, the center-to-center distance between two adjacent radiating slots is 3.2 mm, which is lower than the air wavelength (3.701 mm to 3.945 mm) of the radar operating frequency (76 GHz to 81 GHz), thus avoiding grating lobes in the antenna pattern.

[0060] In a specific embodiment of the present invention, such as Figure 8 and Figure 9 As shown, each first waveguide channel 107 and each second waveguide channel 201 includes a feed cavity 203 (e.g., Figure 4302 in the middle) and connecting cavity 202 (such as Figure 4 (301 in the middle), the first end of the connecting cavity 202 passes through the transition section 204 (such as 301 in the middle), Figure 4 and Figure 5 305) is connected to the feeding cavity 203, and the transition section 204 is located in the middle of the corresponding waveguide cavity. The cavity height corresponding to the transition section 204 of the first waveguide channel 107 and the second waveguide channel 201 is 1mm to 1.5mm, and the width of the transition section 204 is 2.3mm to 2.8mm.

[0061] The cavity corresponding to the transition section 204 between the first waveguide channel 107 and the second waveguide channel 201 can be equivalent to a waveguide H-plane (wide side) transmission line, acting as a waveguide HT power divider. By adjusting the height and width of the transition section 204 (i.e., adjusting the height and width of the cavity corresponding to the transition section 204), the phases of the two radiating slots corresponding to the transition section 204 are kept consistent, and the antenna pattern will not show a 0° position dip, thus achieving parallel in-phase feeding of the four radiating slots in the same row. If the height and width of the transition section 204 are not adjusted (i.e., consistent with the connecting cavity 202 and the feeding cavity 203), the phases of the two radiating slots corresponding to the transition section 204 will be opposite, which will affect the antenna pattern, that is, the phases of the antenna elements will be opposite, the antenna 0° pattern will be dipped, and the gain will be extremely low. The transition section 204 is positioned between the connecting cavity 202 and the feeding cavity 203, improving the symmetry between the first waveguide channel 107 and the second waveguide channel 201, which helps reduce energy leakage after the antenna is actually manufactured. Both the connecting cavity 202 and the feeding cavity 203 of this invention adopt a waveguide E-plane design, which is beneficial for the compact design of the antenna.

[0062] In a specific embodiment of the present invention, such as Figure 9 As shown, the first end of the connecting cavity 202 of the second waveguide channel 201 is provided with a protrusion 206 (e.g., Figure 4 and Figure 5 In the second waveguide channel 201 (306), the protrusion 206 is flush with the transition section 204, and the length of the protrusion 206 is greater than the length of the transition section 204. In this embodiment, the length of the protrusion 206 is 0-0.5 mm longer than the length of the transition section 204. An interface 205 is provided on the bottom surface of the second substrate 200, and a groove (e.g., 306) is provided at the second end of the connecting cavity 202 of the second waveguide channel 201. Figure 5 (307) The groove is connected to the adapter 205. The protrusion 206 and the groove are used to connect the cavity 202 to the transition section 204 and the cavity 202 to the adapter 205, respectively, which reduces the matching deterioration problem caused by the sudden bending of the transmission line.

[0063] To meet the process requirements of metallization of the antenna plastic as much as possible, the inner corners of each waveguide cavity are chamfered by 0.5mm. When the width of the waveguide cavity is 1mm, the two ends of the waveguide cavity are basically a semi-circular structure (e.g., Figure 4 and Figure 5 (304 in the middle).

[0064] Figure 10 The azimuth plane radiation patterns of the transmitting antenna at three frequency points: 77 GHz, 78 GHz, and 79 GHz are shown. Figure 10 It can be seen that the transmitting antenna has a relatively symmetrical structure (mainly due to the consistent spacing of the surrounding metal ridges), a relatively stable and symmetrical azimuth pattern, and a wide beamwidth, with a 6dB beamwidth of approximately 190° and a gain of approximately 11.5dB.

[0065] Figure 11 The azimuth plane radiation patterns of the receiving antenna at three frequency points: 77 GHz, 78 GHz, and 79 GHz are shown. Figure 11 It can be seen that the receiving antenna is not symmetrical enough (mainly for a single receiving antenna, the spacing of the surrounding metal ridges is inconsistent and asymmetrical), and the azimuth pattern is slightly higher on one side, which is not symmetrical enough, but it still has a relatively wide beamwidth, about 170° (i.e., 6dB beamwidth), and a gain of about 12dB.

[0066] Figure 12 The antenna reflection coefficient curve is shown, by Figure 12 It can be seen that the antenna's -10dB operating frequency band is 76.5GHz to 80.5GHz. Figure 13 and Figure 14 The elevation patterns of the transmitting and receiving antennas are shown respectively. Figure 13 and Figure 14 It can be seen that the elevation patterns of the transmitting and receiving antennas are quite similar. The antenna has a low sidelobe (the lower the sidelobe, the better, as the lower the sidelobe, the weaker the energy of clutter received by the antenna in the non-detection direction), about -19dB, which helps to reduce the interference of echoes from non-detection areas during radar detection and improve detection accuracy.

[0067] The above description only discloses specific embodiments of the present invention, but the scope of protection of the present invention is not limited thereto. Any changes or modifications that can be easily conceived by those skilled in the art within the scope of the technology disclosed in the present invention should be included within the scope of protection of the present invention.

Claims

1. A waveguide antenna structure, comprising a first substrate and a second substrate stacked together, wherein a plurality of first waveguide channels are provided on the bottom surface of the first substrate, and a plurality of second waveguide channels are provided on the top surface of the second substrate, wherein the first waveguide channels and the second waveguide channels correspond one-to-one and have the same structural dimensions, and a waveguide cavity is formed by the corresponding and connected first waveguide channels and second waveguide channels; a plurality of rows of radiating slots are provided on the top surface of the first substrate, each row of radiating slots corresponding to and connected to a first waveguide channel; the radiating slots include first radiating slots and second radiating slots, each row of first radiating slots corresponding to a receiving antenna assembly, and each row of second radiating slots corresponding to a transmitting antenna assembly; characterized in that: Each group of first radial slots includes two rows of first radial slots, with two first metal ridges between two adjacent groups of first radial slots, and two second metal ridges on the outermost row of first radial slots; a third metal ridge between two adjacent rows of second radial slots, and two fourth metal ridges on the outermost row of second radial slots. The height of the first, second, third, and fourth metal ridges is 0.5mm to 1mm, and the width is 0.5mm to 1mm; the center distance between adjacent second radiating slots and the third metal ridge, and the center distance between adjacent second radiating slots and the fourth metal ridge are both 0.75 times the air wavelength corresponding to the antenna center frequency; the center distance between adjacent first radiating slots and the first metal ridge, and the center distance between adjacent first radiating slots and the second metal ridge are both 0.75 times the air wavelength corresponding to the antenna center frequency. By coordinating the arrangement of a first, second, third, and fourth metal ridge with a specific number, position, and size, the spatial electric field of the antenna azimuth plane is reflected, so that the energy excited by the reflected wave is out of phase with the antenna energy in the normal direction, while the energy in the surrounding area becomes stronger, thereby widening the 6dB beamwidth of the antenna azimuth plane to 170°~190° and improving beam stability.

2. The waveguide antenna structure according to claim 1, characterized in that: The sum of the heights of the first waveguide channel and the second waveguide channel is 2.8mm to 3.4mm, and the widths of both the first and second waveguide channels are 1mm to 1.4mm.

3. The waveguide antenna structure according to claim 1, characterized in that: The number of first metal ridges between two adjacent sets of first radiation slots, the number of second metal ridges outside the outermost row of first radiation slots, and the number of fourth metal ridges outside the outermost row of second radiation slots are all 2. The number of third metal ridges between two adjacent rows of second radiation slots is 1. The center distance between two adjacent fourth metal ridges is 1.5 times the air wavelength corresponding to the antenna center frequency, and the center distance between two adjacent second metal ridges is 1 time the air wavelength corresponding to the antenna center frequency.

4. The waveguide antenna structure according to claim 1, characterized in that: Compared to the other rows of second radiating slots, the rightmost row of second radiating slots moves upward by a distance equal to 0.5 times the air wavelength corresponding to the antenna's center frequency; The center-to-center distance between the two nearest rows of second radiating slots is 1.5 times the air wavelength corresponding to the antenna center frequency; the center-to-center distance between the nearest third and fourth metal ridges is 1.5 times the air wavelength corresponding to the antenna center frequency.

5. The waveguide antenna structure according to claim 1, characterized in that: The center-to-center distance between the two rows of first radiating slots in each group is 1 times the air wavelength corresponding to the antenna center frequency, and the center-to-center distance between the two nearest groups of first radiating slots is 3.5 times the air wavelength corresponding to the antenna center frequency.

6. The waveguide antenna structure according to claim 1, characterized in that: For each row of first and second radiating slots, the width of each radiating slot is greater than 1 mm and less than 2 mm, the height of each radiating slot is 1 mm to 1.5 mm, the length of each radiating slot is 2 mm to 2.3 mm, and the width of the two radiating slots on both sides is less than the width of the middle radiating slot. The center-to-center distance between two adjacent radiating slots is less than 1 times the air wavelength corresponding to the antenna center frequency.

7. The waveguide antenna structure according to claim 1, characterized in that: For the first and second radial slots in each row, the inner corners of each radial slot are rounded with a radius of 0.5mm.

8. The waveguide antenna structure according to any one of claims 1 to 7, characterized in that: Each first waveguide channel and each second waveguide channel includes a feeding cavity and a connecting cavity, the first end of which is connected to the feeding cavity via a transition section.

9. The waveguide antenna structure according to claim 8, characterized in that: The first end of the connecting cavity of the second waveguide channel is provided with a protrusion, which is flush with the transition section and the length of the protrusion is greater than the length of the transition section; an interface is provided on the bottom surface of the second substrate, and a groove is provided at the second end of the connecting cavity of the second waveguide channel, which communicates with the interface.

10. A radar, characterized in that, The radar includes a waveguide antenna structure as described in any one of claims 1 to 9.

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