Millimeter wave vehicle-mounted radar vertical polarization antenna and antenna array

Abstract

The utility model discloses a millimeter wave vehicle-mounted radar vertical polarization antenna and an antenna array. The antenna comprises a radiation cavity layer, a radiation layer and a feed layer. The radiation cavity layer, the radiation layer and the feed layer are sequentially arranged from top to bottom; the feed layer is provided with a feed cavity; a plurality of rectangular grooves are formed in the radiation layer to form a plurality of radiation slots; the radiation cavity layer is provided with a rectangular cavity at a position opposite to the plurality of radiation slots; the radiation cavity layer and the radiation layer are integrated on the first waveguide layer; the feed layer is integrated on the second waveguide layer; and the first waveguide layer and the second waveguide layer have the same thickness. The utility model has the advantages of simple structure, simple processing and the like.

Description

Technical Field

[0001] This utility model mainly relates to the field of radar antenna technology, specifically to a millimeter-wave vehicle-mounted radar vertical polarization antenna and antenna array. Background Technology

[0002] Currently, millimeter-wave vehicle-mounted radar antennas primarily propagate horizontally and vertically polarized signals. Compared to horizontally polarized signals, vertically polarized signals are less affected by ground interference, resulting in greater signal stability. Furthermore, the number of antennas is a crucial factor determining radar detection accuracy. Increasing the number of antennas leads to more complex feeder layouts, increased losses, and deteriorated isolation. Using waveguide transmission lines and welding processes can effectively avoid these problems. However, the number of layers also affects the quality of fabrication and welding installation. Therefore, a double-layer structure is currently the best choice, ensuring simplicity in antenna feeder layout while reducing the demands on antenna fabrication processes.

[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 (Line-of-Pack) structure (where the chip and waveguide antenna are directly connected via waveguide ports, eliminating the need for PCB adapters). 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. Currently, in waveguide antenna manufacturing, it's best to halve the waveguide cavity in the middle 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 use of waveguide E-plane slots 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] Currently, most mainstream all-metal millimeter-wave vehicle radar antennas propagate horizontally polarized signals. Due to the characteristics of radio waves, horizontally polarized signals will generate polarization currents on the ground surface when they are close to the ground. The polarization currents generate heat due to the influence of the ground impedance, which will cause the electric field signal to decay rapidly, while the radiation pattern will deteriorate and the sidelobes will become worse.

[0005] In addition, many structures cannot be simplified to double-layer processing (the fewer the layers, the lower the processing cost).

[0006] Most existing waveguide slot antennas use a slit-shaped cavity on the wide side (H-plane) of the waveguide for radiation. Since the LOP port layout of existing chips is relatively compact, it is more suitable to use a waveguide E-plane (narrow side) transmission line for the connection between the antenna and the chip. If the antenna feeding cavity is a waveguide H-plane cavity, the heights of the two waveguide segments will be inconsistent. In order to ensure that the waveguide energy does not leak during antenna fabrication, it is best to cut the waveguide into layers from the middle position. If the heights of the two waveguide segments in the same layer are inconsistent, it is impossible to cut both waveguide segments in half, which will affect the performance of the antenna after fabrication.

[0007] For example, patent application CN117352999A discloses a novel 3D millimeter-wave vehicle-mounted radar vertically polarized antenna. Its feed line and antenna feed cavity are designed with waveguide E-plane and waveguide H-plane respectively. The two cavities have different heights, and they cannot be cut symmetrically (in half) at the same time when layered. This may lead to energy leakage in the waveguide, affecting antenna performance and yield. Utility Model Content

[0008] In view of the technical problems existing in the prior art, this utility model provides a millimeter-wave vehicle-mounted radar vertical polarization antenna and antenna array that is simple in structure and easy to manufacture.

[0009] To solve the above-mentioned technical problems, the technical solution proposed by this utility model is as follows:

[0010] A millimeter-wave vehicle-mounted radar vertical polarization antenna includes a radiating cavity layer, a radiating layer, and a feeding layer;

[0011] The radiation cavity layer, radiation layer, and feed layer are arranged sequentially from top to bottom;

[0012] The feeding layer is provided with a feeding cavity;

[0013] The radiation layer has multiple rectangular grooves, forming multiple radiation gaps;

[0014] The radiation cavity layer has rectangular cavities located directly opposite the multiple radiation gaps;

[0015] The radiating cavity layer and the radiating layer are integrated into the first waveguide layer; the feeding layer is integrated into the second waveguide layer; the first waveguide layer and the second waveguide layer have the same thickness.

[0016] As a further improvement to the above technical solution:

[0017] The number of the radial slits is an even number.

[0018] There are four radial slits, arranged in a straight line.

[0019] The width of the two middle radial slits is greater than the width of the two side radial slits.

[0020] The spacing between each of the aforementioned radiation slots is lower than the air wavelength of the radar's operating frequency.

[0021] The width of the two central radial slits is 1.8 mm, and the width of the two side radial slits is 1.2 mm.

[0022] The feeding cavity is equipped with a waveguide feeder assembly, with a waveguide ET power divider connected in the middle of the waveguide feeder assembly, and the two sides of the waveguide feeder assembly facing the radiation slot.

[0023] The waveguide feed assembly includes a first waveguide feed, a second waveguide feed, and a third waveguide feed. The first and third waveguide feeds are both U-shaped. The second waveguide feed is a straight line. One end of the second waveguide feed is connected to one end of the first waveguide feed, and the other end is connected to one end of the third waveguide feed.

[0024] This utility model also discloses a transceiver antenna array, including multiple millimeter-wave vehicle-mounted radar vertical polarization antennas as described above.

[0025] Compared with the prior art, the advantages of this utility model are:

[0026] The antenna structure of this invention is relatively simple. The overall structure can be processed in two layers. The upper and lower waveguide cavity structures are very consistent and symmetrical, and can be processed using plastic metallization technology, which is beneficial for low-cost antenna processing and improving the yield rate of finished antenna products. Both the connecting waveguide and the feed waveguide of the antenna adopt the waveguide E-plane (narrow side) design, which is conducive to the compact design of the antenna. The antenna has a large bandwidth and can cover the entire vehicle radar frequency band (76-81GHz). The antenna of this invention is a vertically polarized antenna, which can effectively reduce external interference to the antenna signal propagation and improve radar performance. Attached Figure Description

[0027] Figure 1 This is a functional structure diagram of the antenna of this utility model in an embodiment.

[0028] Figure 2 This is a layered structure diagram of the antenna of this utility model in an embodiment.

[0029] Figure 3 This is a top view of the antenna of this utility model in an embodiment.

[0030] Figure 4 This is a structural diagram of the power feeding cavity and radiation slot of this utility model in an embodiment.

[0031] Figure 5 This is a top view of the power supply cavity and radiation slot of this utility model in an embodiment.

[0032] Figure 6 This is one of the structural diagrams of the four-transmitter, four-receiver antenna array of this utility model in an embodiment.

[0033] Figure 7 This is the second structural diagram of the four-transmitter, four-receiver antenna array of this utility model in an embodiment.

[0034] Figure 8 This is a structural diagram of the antenna array feed layer of this utility model in an embodiment.

[0035] Figure 9 The figure shows the simulation results of the antenna S-parameters of this utility model.

[0036] Figure 10 This is the antenna elevation pattern of this utility model (three frequency points: 76, 78, and 81 GHz).

[0037] Figure 11 This is the antenna azimuth pattern of this utility model (three frequency points: 76, 78, and 81 GHz).

[0038] Legend: 11. Radiation cavity layer; 21. Radiation layer; 31. Feed layer; 12. Rectangular cavity; 22. Radiation slot; 32. Feed cavity; 311. First waveguide feed line; 312. Second waveguide feed line; 313. Third waveguide feed line; 321. Waveguide ET power divider; 322. Bottom edge feed line. Detailed Implementation

[0039] The present invention will be further described below with reference to the accompanying drawings and specific embodiments.

[0040] like Figure 1 As shown, the millimeter-wave vehicle-mounted radar vertical polarization antenna of this utility model embodiment has an overall antenna structure divided into three layers (divided into three layers according to function, and can be processed in two layers during processing), namely, the radiation cavity layer 11, the radiation layer 21 and the feed layer 31.

[0041] The bottom feed layer 31 of the antenna is designed with a waveguide E-plane (narrow side). The feed layer 31 is provided with a feed cavity 32, and the feed cavity 32 is provided with a waveguide feed line assembly.

[0042] Above the feed layer 31 is the radiation layer 21, which has four rectangular metal slots of different sizes (two large in the middle and two small at the edges) to form radiation slots 22. The radiation slots 22 radiate through the current cutting the waveguide surface.

[0043] Above the radiating layer 21 is the radiating cavity layer 11, on which a rectangular cavity 12 is set on the four radiating slots 22, which is beneficial to the stability of the antenna beam, the improvement of the isolation between antennas, and the suppression of sidelobes.

[0044] like Figure 2 As shown, this is a layered structure diagram during antenna fabrication. It is fabricated in two layers. Since the waveguide cavity is best fabricated by cutting it from the middle, it is cut from the middle of the waveguide cavity, resulting in a first waveguide layer 1A and a second waveguide layer 2A. In the first waveguide layer 1A, the radiation cavity layer 11 and the radiation layer 21 are fabricated as a single unit, while the second waveguide layer 2A is fabricated separately.

[0045] like Figure 3 As shown, the antenna has four radiating slots 22, which can be increased or decreased according to beam requirements, such as 2, 4, 6, or 8. The spacing between the radiating slots 22 is set to 3.2 mm, which is lower than the air wavelength (3.701 mm - 3.945 mm) of the radar operating frequency (76-81 GHz). According to array antenna theory, in order to avoid grating lobes, when the antenna array is a side-firing array, the spacing between antenna elements needs to be less than one air wavelength. The width of the four radiating slots 22 can be changed to adjust the impedance matching of the antenna, provided that the manufacturing conditions are met (width greater than 1 mm). The optimized radiating slot 22 in the middle position has a width of 1.8 mm, and the two side slots have a width of 1.2 mm.

[0046] like Figure 4 and Figure 5 The figures show a structural diagram and a top view of the feeding cavity 32 and the four radiation slots 22, respectively. The feeding cavity 32 houses a waveguide feeder assembly, with a waveguide ET power divider connected in the middle of the waveguide feeder assembly. Both sides of the waveguide feeder assembly (i.e., the first waveguide feeder 311 and the third waveguide feeder 313) face the radiation slots. Specifically, the waveguide feeder assembly includes a first waveguide feeder 311, a second waveguide feeder 312, and a third waveguide feeder 313. The first waveguide feeder 311 and the third waveguide feeder 313 are both U-shaped; the second waveguide feeder 312 is a straight line; one end of the second waveguide feeder 312 is connected to one end of the first waveguide feeder 311, and the other end is connected to one end of the third waveguide feeder 313.

[0047] Of course, in other embodiments, the parallel feed can be changed to a series feed, that is, the feed line is fed in from one of the front and rear sides instead of from the middle.

[0048] To meet processing requirements, the chamfers at all locations within the feeding cavity 32 are at least 0.5 mm. Taking the first waveguide feed line 311 as an example, both the inner and outer sides of this right angle are chamfered, with the inner chamfer being 0.5 mm and the outer chamfer being 1 mm. The feeding method adopts a parallel feeding form of the waveguide E-plane (narrow side), with the waveguide ET power divider 321 feeding from one side of the middle of the feed line, providing in-phase feeding to the four radiation slots 22, which are collinearly arranged.

[0049] Figure 5The three arrows in the diagram represent the electric field directions at different locations in the simulated waveguide (Note: This is an electric field pointing diagram that does not consider the phase shift caused by the feeder length. The feeder length mainly refers to the length of the bottom edge of the first waveguide feeder 311. The change in this length will cause the phase of the two edge radiation slots 22 to be inconsistent with that of the two middle radiation slots 22). The electromagnetic wave is fed into the input of the waveguide power divider. After passing through the waveguide ET power divider 321, it will output two electromagnetic waves with the same amplitude but opposite phase (e.g., ...). Figure 5 As shown in the diagram, the electric fields on the left and right sides point in opposite directions. However, when the two electromagnetic waves reach the two middle radiating slots 22 after each 90° bend, their electric field directions relative to the radiating slots 22 are consistent. This allows the two radiating slots 22 to radiate in phase. The electromagnetic waves continue to propagate along the feed line. It can be seen that, without considering the phase shift caused by the length of the bottom feed line 322, the electric field directions of the two electromagnetic waves at the two edge radiating slots 22 are consistent but opposite to the electric field direction of the middle radiating slot 22. To ensure that the four radiating slots 22 radiate in phase, the length of the bottom feed line 322 needs to be an odd multiple of half a waveguide wavelength (the phase of the electromagnetic wave changes periodically; the phase is consistent every waveguide wavelength during propagation, and opposite when the phase is half a waveguide wavelength apart). Considering the distance between the slots, 1.5 waveguide wavelengths are selected here.

[0050] Waveguide wavelength calculation formula:

[0051]

[0052] Where λ c λ is the waveguide cutoff wavelength, and λ is the air wavelength. g Where is the waveguide wavelength, a is the length of the wide side of the waveguide (e.g., 3.2 mm), and b is the length of the narrow side (e.g., 1 mm). The dominant mode of the rectangular waveguide is the TE10 mode, i.e., m = 1 and n = 0 in this formula.

[0053] The calculated waveguide wavelength is approximately 4.76 mm, therefore the length of the bottom feed line 322 between the two radiation slots 22 on the same side is approximately 7 mm (the result can be adjusted based on the simulation results).

[0054] like Figures 6-7 As shown, a 4-transmit, 4-receive transceiver antenna array is constructed using the above antenna structure. The routing of the waveguide feed lines is not fixed, as shown below. Figure 5 As shown, the antenna element distribution is also not fixed and can be directly connected to the chip's LOP interface to achieve radar detection functionality. Figure 8 2B and Figure 7 The 2C section is a vertical adapter structure that connects four transmit and four receive antennas to the chip's eight LOP ports.

[0055] like Figure 9As shown, the antenna's S11 is below -15dB in the 76-81GHz range, meeting the requirements of automotive millimeter-wave radar.

[0056] like Figure 10 As shown, the antenna gain is approximately 15dB, the elevation beamwidth is 6dB and the sidelobes are better than -25dB at 78 and 81 GHz, and better than -21dB at 76 GHz, indicating low sidelobes.

[0057] like Figure 11 As shown, the antenna azimuth pattern is relatively consistent, and the 6dB beamwidth is approximately 87°.

[0058] The antenna structure of this invention is relatively simple. The overall structure can be processed in two layers. The upper and lower waveguide cavity structures are very consistent and symmetrical, and can be processed using plastic metallization technology, which is beneficial for low-cost antenna processing and improving the yield rate of finished antenna products. Both the connecting waveguide and the feed waveguide of the antenna adopt the waveguide E-plane (narrow side) design, which is conducive to the compact design of the antenna. The antenna has a large bandwidth and can cover the entire vehicle radar frequency band (76-81GHz). The antenna of this invention is a vertically polarized antenna, which can effectively reduce external interference to the antenna signal propagation and improve radar performance.

[0059] The above are merely preferred embodiments of this utility model. The protection scope of this utility model is not limited to the above embodiments. All technical solutions falling within the scope of this utility model's concept are within its protection scope. It should be noted that for those skilled in the art, any improvements and modifications made without departing from the principle of this utility model should be considered within its protection scope.

Claims

1. A millimeter-wave vehicle-mounted radar vertically polarized antenna, characterized in that, It includes a radiation cavity layer (11), a radiation layer (21), and a feed layer (31); The radiation cavity layer (11), radiation layer (21) and feed layer (31) are arranged sequentially from top to bottom; A feeding cavity (32) is provided on the feeding layer (31); The radiation layer (21) is provided with a plurality of rectangular grooves, forming a plurality of radiation gaps (22); The radiation cavity layer (11) has rectangular cavities (12) located opposite to the multiple radiation gaps (22); The radiation cavity layer (11) and the radiation layer (21) are integrated in the first waveguide layer; the feed layer (31) is integrated in the second waveguide layer; the first waveguide layer and the second waveguide layer have the same thickness.

2. The millimeter-wave vehicle-mounted radar vertical polarization antenna according to claim 1, characterized in that, The number of the radiation slits (22) is an even number.

3. The millimeter-wave vehicle-mounted radar vertical polarization antenna according to claim 2, characterized in that, The number of the radiation slits (22) is four, arranged in a straight line.

4. The millimeter-wave vehicle-mounted radar vertical polarization antenna according to claim 3, characterized in that, The width of the two middle radial slits (22) is greater than the width of the two side radial slits (22).

5. The millimeter-wave vehicle-mounted radar vertical polarization antenna according to claim 4, characterized in that, The width of the two middle radial slits (22) is 1.8 mm, and the width of the two side radial slits (22) is 1.2 mm.

6. The millimeter-wave vehicle-mounted radar vertical polarization antenna according to any one of claims 1-5, characterized in that, The spacing between each of the radiation slits (22) is lower than the air wavelength of the radar operating frequency.

7. The millimeter-wave vehicle-mounted radar vertical polarization antenna according to any one of claims 1-5, characterized in that, The feeding cavity (32) is provided with a waveguide feeder assembly, and a waveguide ET power divider (321) is connected in the middle of the waveguide feeder assembly. The two sides of the waveguide feeder assembly face the radiation slot (22).

8. The millimeter-wave vehicle-mounted radar vertical polarization antenna according to claim 7, characterized in that, The waveguide feed assembly includes a first waveguide feed (311), a second waveguide feed (312), and a third waveguide feed (313). The first waveguide feed (311) and the third waveguide feed (313) are both U-shaped. The second waveguide feed (312) is a straight line. One end of the second waveguide feed (312) is connected to one end of the first waveguide feed (311), and the other end is connected to one end of the third waveguide feed (313).

9. A transceiver antenna array, characterized in that, It includes multiple millimeter-wave vehicle-mounted radar vertical polarization antennas as described in any one of claims 1-8.

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