Waveguide antenna structure and radar

Abstract

The invention discloses a waveguide antenna structure and a radar, and relates to the field of waveguide antennas. The antenna structure comprises a first substrate and a second substrate, wherein a waveguide cavity is formed by a first waveguide channel arranged on the bottom surface of the first substrate and a second waveguide channel arranged on the top surface of the second substrate; the top surface of the first substrate is provided with a plurality of rows of radiation slots, and each row of radiation slots is communicated with the corresponding first waveguide channel. The radiation slots comprise a first radiation slot and a second radiation slot; each group of first radiation slots comprises two rows of first radiation slots, a first metal ridge is arranged between two adjacent groups of first radiation slots, and a second metal ridge is arranged on the outer side of the outermost row of first radiation slots; a third metal ridge is arranged between two adjacent rows of second radiation slots, and a fourth metal ridge is arranged on the outer side of the outermost row of second radiation slots. According to the invention, the antenna beam width is widened, the beam is stabilized, and the radar can realize a large detection range.

Description

Technical Field

[0001] The present invention belongs to the technical field of waveguide antennas, and particularly relates to a waveguide antenna structure and a radar. Background Art

[0002] Compared with microstrip antennas, waveguide antennas have very low losses because there is no dielectric loss. Especially when the size of the antenna array is large and the feeder is long, they have higher efficiency. Common forms of waveguide antennas include SIW (Substrate Integrated Waveguide) slot antennas, gap waveguide antennas, rectangular waveguide slot antennas, etc., which can be used to receive or transmit electromagnetic waves.

[0003] In the design of common waveguide slot antennas, generally, the radiation is designed by opening slots on the H-plane (i.e., the wide side of the waveguide). Currently, automotive millimeter-wave radar chips will adopt the LOP (Launch On Package) structure, that is, the chip is directly connected to the waveguide antenna through the waveguide port without the need for PCB transfer. The distances between the waveguide outlets of the chip are generally short. In order to make the wiring more compact and meet the processing conditions (the distance between each waveguide transmission line is greater than 1 mm), generally, waveguide E-plane (i.e., the narrow side of the waveguide) transmission lines are used to connect the antenna to each chip. If the antenna uses the H-plane slot radiation method, it will cause the situation that the heights of two parts of the entire waveguide cavity are inconsistent; since currently, when processing waveguide antennas, it is best to cut the waveguide cavity in half in the middle for layered processing to better ensure that there is no energy leakage after assembly. If the heights of the two parts of the waveguide cavity are inconsistent, it is not conducive to realizing the half-cut layered processing of both waveguide cavities. Therefore, the millimeter-wave radar antenna using the E-plane slot radiation method is more beneficial to the compactness of the antenna structure and the yield of processed antennas.

[0004] When designing the feeding of the antenna, it is directly transferred from a section of the waveguide H-plane to the waveguide E-plane cavity. In order to ensure factors such as the simplicity and easy processing of the overall structure and the symmetry of the cavity height and length, some adjustment and matching structures are not added, resulting in limited bandwidth and inability to cover the entire frequency range defined by 76 GHz to 81 GHz for automotive radars. In the field of automotive radars, although the metal plasticization processing technology reduces the processing cost of rectangular waveguide antennas and has advantages such as large bandwidth, large power capacity, low loss, and high efficiency, the processing manufacturer requires chamfering at some positions, making the end of the waveguide semi-circular, which affects the antenna matching.

[0005] The patent document with the application publication number CN118610743A discloses an E-plane waveguide antenna structure. Its electromagnetic bandgap structure is a high-impedance surface formed by periodic metal columns, which makes electromagnetic waves unable to propagate in this direction and plays a role in confining electromagnetic waves. As a result, the beam width in the azimuth plane of the antenna is relatively narrow and it is not applicable to radar systems for large-angle detection. In order to change the phase of the cavity and the amplitude distribution of each slot and reduce the sidelobes, a waveguide part, steps, etc. are added between the radiation slots, making the upper and lower parts of the waveguide cavity less symmetrical, the structure more complex, and increasing the processing difficulty.

[0006] The patent document with the application publication number CN115566400A discloses a 3D metallized vehicle-mounted millimeter-wave radar antenna. The structure of its feeding cavity part is too complex to be applicable to metal plastic processing and cannot be processed in a double-layer manner.

[0007] The antenna is the "eye" of the radar system. Some radars (such as corner radars) require an extremely wide detection range, which requires the antenna to have a wide-beam pattern. In the current waveguide antenna design, the design of a wide beam is not common. In order to improve the detection range of the radar, for the application of a wide-beam antenna in vehicle-mounted radars, a double-layer waveguide antenna with a wide beam, a simple structure, and easy processing needs to be designed. Summary of the Invention

[0008] The purpose of the present invention is to provide a waveguide antenna structure and a radar to solve at least one of the problems that the traditional antenna structure has a narrow beam width and is not applicable to radar systems for large-angle detection, and the cavity structure is asymmetrical, resulting in a complex structure and increasing the processing difficulty.

[0009] The present invention solves the above technical problems through the following technical solutions: A waveguide antenna structure includes a first substrate and a second substrate stacked. On the bottom surface of the first substrate, there are multiple first waveguide channels. On the top surface of the second substrate, there are multiple second waveguide channels. The first waveguide channels and the second waveguide channels correspond one by one and have the same structural dimensions. A waveguide cavity is formed by the corresponding and connected first waveguide channels and second waveguide channels. On the top surface of the first substrate, there are multiple rows of radiation slots. Each row of radiation slots corresponds to a first waveguide channel and is connected to the corresponding first waveguide channel. The radiation slots include first radiation slots and second radiation slots. Each row of first radiation slots corresponds to a receiving antenna assembly, and each row of second radiation slots corresponds to a transmitting antenna assembly.

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

[0011] Compared with the electromagnetic bandgap structure, on the one hand, the structure of the metal ridge is simpler and easier to process; on the other hand, the metal ridge can reflect the spatial electric field portion of the antenna azimuth plane, reducing the gain of the antenna normal direction and widening the antenna beam width; the first waveguide channel and the second waveguide channel of the present invention have the same structural dimensions and are symmetrical, which facilitates the use of metal plastic processing technology for processing, is conducive to low-cost processing of the antenna, improves the yield rate of the finished antenna product, and reduces electromagnetic wave leakage in the waveguide cavity after processing.

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

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

[0014] Furthermore, the number of first metal ridges between two adjacent groups 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 times the air wavelength corresponding to the antenna center frequency.

[0015] Furthermore, relative to other rows of second radiation slots, the distance that the rightmost row of second radiation slots moves upward is 0.5 times the air wavelength corresponding to the center frequency of the antenna; the center distance between the two most adjacent rows of second radiation slots is 1.5 times the air wavelength corresponding to the center frequency of the antenna; and the center distance between the most adjacent third metal ridge and fourth metal ridge is 1.5 times the air wavelength corresponding to the center frequency of the antenna.

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

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

[0018] Further, for each row of the first radiation slots and each row of the second radiation slots, a 0.5 mm fillet is used for each inner angle of the radiation slot.

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

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

[0021] Based on the same concept, the present invention further provides a radar, and the radar includes the waveguide antenna structure as described above.

[0022] Advantageous Effects

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

[0024] The present invention provides metal ridges around the radiation slots. The metal ridges can reflect a part of the spatial electric field in the azimuth plane of the antenna. The energy excited by the reflected wave is opposite in phase to the energy of the antenna, making the energy at the 0° position of the antenna weaker and the energy around it stronger, improving the antenna beam width and stabilizing the beam, which is beneficial for the radar to achieve a larger detection range; at the same time, compared with the electromagnetic bandgap structure, the structure of the metal ridges is simpler and easier to process, and the structural dimensions of the first waveguide channel and the second waveguide channel are the same and symmetric, and the antenna structure can be cut in half and processed in a double-layer manner, which is beneficial for the low-cost processing of the antenna, improving the yield of the antenna finished product and reducing the electromagnetic wave leakage in the waveguide cavity after processing.

[0025] The position of a row of radiation slots corresponding to the rightmost transmitting antenna (i.e., the second radiation slot in the rightmost row) is moved upward, and every two rows of first radiation slots are taken as a group, and a first metal ridge is provided between each group of first radiation slots, so that the radar can measure the height in the elevation plane. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] In order to more clearly illustrate the technical solutions of the present invention, the drawings required for the description of the embodiments will be briefly introduced below. Obviously, the drawings in the following description are only one embodiment of the present invention, and those of ordinary skill in the art can obtain other drawings based on these drawings without creative efforts.

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

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

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

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

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

[0032] Figure 6 is a schematic diagram of the position and size of the radiation slots and metal ridges in an embodiment of the present invention;

[0033] Figure 7 is a schematic diagram of the size of a single row of first radiation slots or a single row of second radiation slots in an embodiment of the present invention;

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

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

[0036] Figure 10 is the azimuth plane pattern of the transmitting antenna in an embodiment of the present invention;

[0037] Figure 11 is the azimuth plane pattern of the receiving antenna in an embodiment of the present invention;

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

[0039] Figure 13 is the elevation plane radiation pattern of the transmitting antenna in the embodiment of the present invention;

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

[0041] Description of reference numerals: 100 - first substrate, 101 - second radiation slot, 102 - third metal ridge, 103 - fourth metal ridge, 104 - first radiation slot, 105 - second metal ridge, 106 - first metal ridge, 107 - first waveguide channel, 200 - second substrate, 201 - second waveguide channel, 202 - connection cavity, 203 - feeding cavity, 204 - transition section, 205 - adapter, 206 - protrusion, 301 - part to be removed from the connection cavity during processing, 302 - part to be removed from the feeding cavity during processing, 303 - part to be removed from the radiation slot during processing, 304 - chamfering effect at the inner corner of the feeding cavity, 305 - part to be removed from the transition section during processing, 306 - part to be removed from the first end of the connection cavity during processing, 307 - part to be removed from the second end of the connection cavity during processing. Detailed implementation manners

[0042] The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without making creative efforts shall fall within the protection scope of the present invention.

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

[0044] The embodiment of the present invention takes 4 transmitting antennas and 4 receiving antennas as examples to illustrate the waveguide antenna structure. As Figures 1 to 5As shown in the figure, a waveguide antenna structure provided by an embodiment of the present invention includes a first substrate 100 and a second substrate 200 which are stacked. 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 to each other one by 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 radiation slots are provided on the top surface of the first substrate 100. Each row of radiation slots corresponds to one first waveguide channel 107 and is connected to the corresponding first waveguide channel 107. The eight rows of radiation slots include four rows of first radiation slots 104 and four rows of second radiation slots 101. The four rows of first radiation slots 104 respectively correspond to four receiving antenna components, and the four rows of second radiation slots 101 respectively correspond to four transmitting antenna components. Each group of first radiation slots 104 includes two rows of first radiation slots 104. A first metal ridge 106 is provided between adjacent groups of first radiation slots 104, and a second metal ridge 105 is provided outside the outermost row of first radiation slots 104, that is, a second metal ridge 105 is provided outside the leftmost row of first radiation slots 104 and a second metal ridge 105 is provided outside the rightmost row of first radiation slots 104. A third metal ridge 102 is provided between adjacent two rows of second radiation slots 101, and a fourth metal ridge 103 is provided outside the outermost row of second radiation slots 101, that is, a fourth metal ridge 103 is provided outside the leftmost row of second radiation slots 101 and a fourth metal ridge 103 is provided outside the rightmost row of second radiation slots 101.

[0045] Metal ridges are added on both sides of the radiation slots. The metal ridges reflect a part of the spatial electric field in the azimuth plane of the antenna. The energy excited by the reflected wave has a phase opposite to that of the energy of the antenna, making the energy at the 0° position of the antenna weaker and the surrounding energy stronger, improving the antenna beam width and stabilizing the beam, which is beneficial for the radar to achieve a larger detection range. In order to meet the processing conditions of antenna plastic metallization and reduce the leakage of electromagnetic waves in the waveguide cavity after processing, the structures and dimensions of the first waveguide channels 107 and the second waveguide channels 201 are completely the same and symmetrical. The waveguide antenna structure of the present invention is relatively simple, can be processed in two layers, has a low processing cost, a small assembly difficulty, and a high yield.

[0046] Since the distance between the two rows of first radiation slots 104 in each group is small, setting a metal ridge between the two rows of first radiation slots 104 will affect the matching of the antenna and compress the azimuth pattern of the antenna. Therefore, no metal ridge is set between the two rows of first radiation slots 104 in each group. A third metal ridge 102 is added between the two rows of second radiation slots 101, ensuring the consistency of the antenna pattern.

[0047] In a specific embodiment of the present invention, the sum of the heights of the first waveguide channel 107 and the second waveguide channel 201 is 2.8 mm to 3.4 mm, and the widths of the first waveguide channel 107 and the second waveguide channel 201 are both 1 mm (meeting the processing requirements) to 1.4 mm. The sum of the heights of the first waveguide channel 107 and the second waveguide channel 201 is preferably 3.2 mm, and the widths of the first waveguide channel 107 and the second waveguide channel 201 are both preferably 1 mm. Setting the width to 1 mm is the minimum processing requirement. The lower the width, the more convenient it is to design equal line lengths (in-phase) for each antenna, etc.

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

[0049] Exemplarily, for an antenna center frequency of 78 GHz, the corresponding air wavelength is approximately 3.8 mm. Then, the center distance between the adjacent second radiation slot 101 and the third metal ridge 102 is 2.85 mm, and the center distance between the adjacent second radiation slot 101 and the fourth metal ridge 103 is 2.85 mm; the center distance between the adjacent first radiation slot 104 and the first metal ridge 106 is 2.85 mm, and the center distance between the adjacent first radiation slot 104 and the second metal ridge 105 is 2.85 mm, as Figure 6 shown.

[0050] The function of the metal ridge is to broaden the beam width of the antenna in the azimuth plane and stabilize the beam. The metal ridge will reflect some surface waves, and metal ridges with different heights and different positions will control the phase of the reflected waves. When the energy excited by the reflected wave is out of phase with the energy of the antenna, the energy at the 0° position of the antenna will become weaker, and the energy around it will become stronger, that is, the beam width of the antenna is broadened. By optimizing the design to determine the height, width, and position of each metal ridge, the broadening of the antenna beam width is achieved. The original 6 dB beam width can be broadened to 190°, greatly increasing the detection range of the radar.

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

[0052] Exemplarily, for an antenna with a center frequency of 78 GHz, the corresponding air wavelength is about 3.8 mm. Then the center distance between two fourth metal ridges 103 is 5.7 mm, and the center distance between two second metal ridges 105 is 3.8 mm, as Figure 6 shown. In order to balance the azimuth pattern of the antenna as much as possible, the center distance between two second metal ridges 105 is adjusted. When the center distance between 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 reaches balance.

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

[0054] Exemplarily, for an antenna with a center frequency of 78 GHz, the corresponding air wavelength is about 3.8 mm. Then the distance that the rightmost row of the second radiation slots 101 moves upward is 1.9 mm; the center distance between two adjacent rows of the second radiation slots 101 is 5.7 mm; the center distance between the nearest third metal ridge 102 and the fourth metal ridge 103 is 5.7 mm, as Figure 6 shown.

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

[0056] Exemplarily, for an antenna with a center frequency of 78 GHz, the corresponding air wavelength is approximately 3.8 mm. Then, the center distance between two rows of the first radiation slots 104 in each group is 3.8 mm, and the center distance between the two nearest groups of the first radiation slots 104 is 13.3 mm, as Figure 6 shown.

[0057] The structure of each transceiver antenna (i.e., the size, length of the radiation slot, and the size of the waveguide cavity) is exactly the same. To meet the processing conditions of antenna plastic metallization, the width of the metal layer between antennas is 1 mm, the inner corners of each radiation slot are rounded with a radius of 0.5 mm, and the width of the radiation slot is greater than 1 mm.

[0058] In a specific embodiment of the present invention, for each row of the first radiation slots 104 and each row of the second radiation slots 101, the width of each radiation slot (such as 303 in Figure 4 and Figure 5 ) is greater than 1 mm and less than 2 mm, the height of each radiation slot is 1 mm - 1.5 mm, the length of each radiation slot is 2 mm - 2.3 mm, and the widths of the two radiation slots on both sides are smaller than the width of the middle radiation slot. The center distance between two adjacent radiation slots is less than 1 time the air wavelength corresponding to the center frequency of the antenna and greater than the radiation slot length + 1 mm (meeting the processing requirements).

[0059] In this embodiment, in each row of the first radiation slots 104 or each row of the second radiation slots 101, as shown in Figure 7 , the widths of the radiation slots on both sides are preferably 1.4 mm, and the widths of the two middle radiation slots are preferably 1.7 mm. The increase in the width of the radiation slot is beneficial for the antenna to achieve matching with free space in a wide frequency band and is beneficial for improving the bandwidth of the antenna. In this embodiment, the center distance between two adjacent radiation slots is 3.2 mm, which is lower than the air wavelength (3.701 mm - 3.945 mm) corresponding to the radar operating frequency (76 GHz - 81 GHz), avoiding the appearance of grating lobes in the antenna pattern.

[0060] In a specific embodiment of the present invention, as shown in Figure 8 and Figure 9 , each first waveguide channel 107 and each second waveguide channel 201 include a feeding cavity 203 (such as Figure 4in 302) and the connection cavity 202 (such as Figure 4 in 301), the first end of the connection cavity 202 passes through the transition section 204 (such as Figure 4 and Figure 5 in 305) and is connected to the feeding cavity 203. 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 1 mm to 1.5 mm, and the width of the transition section 204 is 2.3 mm to 2.8 mm.

[0061] The cavity corresponding to the transition section 204 of the first waveguide channel 107 and the second waveguide channel 201 can be equivalent to a section of waveguide H-plane (broadside) transmission line, which functions as a waveguide H-T 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 radiation slots corresponding to the transition section 204 are kept consistent, and the antenna pattern does not have a depression at the 0° position, realizing the parallel in-phase feeding of the four radiation slots in the same row. If the height and width of the transition section 204 are not adjusted (i.e., the same as those of the connection cavity 202 and the feeding cavity 203), the phases of the two radiation slots corresponding to the transition section 204 will be opposite, which will affect the antenna pattern, that is, the antenna elements are out of phase, and the antenna 0° pattern will have a depression and extremely low gain. The transition section 204 is arranged between the connection cavity 202 and the feeding cavity 203, improving the symmetry between the first waveguide channel 107 and the second waveguide channel 201, which is beneficial to reducing the energy leakage after the actual processing of the antenna. The connection cavity 202 and the feeding cavity 203 of the present invention both adopt the waveguide E-plane design, which is beneficial to the compact design of the antenna.

[0062] In the specific embodiment of the present invention, as Figure 9 shown, a protrusion 206 (such as Figure 4 and Figure 5 in 306) is provided at the first end of the connection cavity 202 of the second waveguide channel 201. The protrusion 206 of the second waveguide channel 201 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 to 0.5 mm longer than the length of the transition section 204. A transfer interface 205 is provided on the bottom surface of the second substrate 200, and a groove (such as Figure 5 in 307) is provided at the second end of the connection cavity 202 of the second waveguide channel 201. The groove communicates with the transfer interface 205. The connection between the connection cavity 202 and the transition section 204, and the connection between the connection cavity 202 and the transfer interface 205 are respectively realized through the protrusion 206 and the groove, reducing the problem of deteriorated matching caused by the sudden bending of the transmission line.

[0063] To best meet the technological requirements for the plastic metallization processing of the antenna, a chamfer of 0.5 mm has been applied to the inner corners of each waveguide cavity. When the width of the waveguide cavity is 1 mm, the two ends of the waveguide cavity are basically in a semi-circular structure (such as Figure 4 and Figure 5 304 in).

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

[0065] Figure 11 shows the azimuth plane radiation patterns of the receiving antenna at three frequency points of 77 GHz, 78 GHz, and 79 GHz. As Figure 11 can be seen, due to the asymmetrical structure of the receiving antenna (mainly for a single receiving antenna, the spacing of the surrounding metal ridges is inconsistent and asymmetrical), one side of the azimuth plane radiation pattern is slightly higher and less symmetrical. However, it still has a relatively wide beam width, with a beam width of approximately 170° (i.e., the 6 dB beam width), and the gain is approximately 12 dB.

[0066] Figure 12 shows the antenna reflection coefficient curve. As Figure 12 can be seen, the -10 dB operating frequency band of the antenna is 76.5 GHz to 80.5 GHz. Figure 13 and Figure 14 show the elevation plane radiation patterns of the transmitting antenna and the receiving antenna respectively. As Figure 13 and Figure 14 can be seen, the elevation plane radiation patterns of the transmitting and receiving antennas are relatively close. The lower side lobes of the antenna (the lower the side lobes, the better, as the lower the side lobes, the weaker the energy of the clutter received by the antenna in non-detection directions) are approximately -19 dB, which is beneficial to reducing the interference of echoes in non-detection areas during radar detection and improving the detection accuracy.

[0067] The above-disclosed are only the specific embodiments of the present invention, but the protection scope of the present invention is not limited thereto. Any person skilled in the art within the technical scope disclosed by the present invention can easily think of changes or variations, which should all be covered within the protection scope of the present invention.

Claims

1. A waveguide antenna structure, comprising a first substrate and a second substrate which are stacked. 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. The first waveguide channels and the second waveguide channels correspond to each other one by one and have the same structural dimensions. A waveguide cavity is formed by the corresponding and communicating first waveguide channel and second waveguide channel. A plurality of rows of radiation slots are provided on the top surface of the first substrate. Each row of radiation slots corresponds to one first waveguide channel and is communicated with the corresponding first waveguide channel. The radiation slots include first radiation slots and second radiation slots. Each row of first radiation slots corresponds to a receiving antenna assembly, and each row of second radiation slots corresponds to a transmitting antenna assembly. It is characterized in that: Each group of first radiation slots includes two rows of first radiation slots. A first metal ridge is provided between adjacent groups of first radiation slots, and a second metal ridge is provided outside the outermost row of first radiation slots. A third metal ridge is provided between adjacent two rows of second radiation slots, and a fourth metal ridge is provided outside the outermost row of second radiation slots.

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

3. The waveguide antenna structure according to claim 1, wherein: The heights of the first metal ridge, the second metal ridge, the third metal ridge and the fourth metal ridge are 0.5 mm to 1 mm, and the widths are 0.5 mm to 1 mm. The center distances between the adjacent second radiation slots and the third metal ridge, and between the adjacent second radiation slots and the fourth metal ridge are both 0.75 times of the air wavelength corresponding to the antenna center frequency. The center distances between the adjacent first radiation slots and the first metal ridge, and between the adjacent first radiation slots and the second metal ridge are both 0.75 times of the air wavelength corresponding to the antenna center frequency.

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

5. The waveguide antenna structure according to claim 1, characterized in that: The upward movement distance of the rightmost row of second radiation slots relative to other rows of second radiation slots is 0.5 times of the air wavelength corresponding to the antenna center frequency. The center distance between the nearest two rows of second radiation slots is 1.5 times of the air wavelength corresponding to the antenna center frequency. The center distance between the nearest third metal ridge and the fourth metal ridge is 1.5 times of the air wavelength corresponding to the antenna center frequency.

6. The waveguide antenna structure according to claim 1, wherein: The center distance between the two rows of first radiation slots in each group is 1 time of the air wavelength corresponding to the antenna center frequency, and the center distance between the nearest two groups of first radiation slots is 3.5 times of the air wavelength corresponding to the antenna center frequency.

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

8. The waveguide antenna structure according to claim 1, wherein: For each row of first radiation slots and each row of second radiation slots, the inner corner of each radiation slot is rounded by 0.5 mm.

9. The waveguide antenna structure according to any one of claims 1 to 8, characterized in that: Each first waveguide channel and each second waveguide channel includes a feeding cavity and a connecting cavity, and a first end of the connecting cavity is connected to the feeding cavity through a transition section; Preferably, a protrusion is provided at the first end of the connecting cavity of the second waveguide channel, the protrusion is flush with the transition section, and the length of the protrusion is greater than the length of the transition section; a transfer 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, and the groove is connected to the transfer interface.

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

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