A forward millimeter wave radar antenna

Abstract

The application relates to a forward millimeter wave radar antenna. The application comprises a body and a wide-beam waveguide antenna, a narrow-beam waveguide antenna and waveguide transmission channels integrated in the body, wherein the waveguide transmission channels comprise a first waveguide transmission channel and a second waveguide transmission channel; the wide-beam waveguide antenna comprises a polarization conversion structure; an antenna unit comprises a first antenna radiation cavity, a first slot radiation groove and a first open horn connected in sequence, and the polarization conversion structure is connected with the first antenna radiation cavity; a first choke groove; the narrow-beam waveguide antenna comprises a splitter connected with the second waveguide transmission channel; an antenna structure array comprises a plurality of sub antenna structure units, each of which comprises a second antenna radiation cavity, a second slot radiation groove and a second open horn connected in sequence; and a second choke groove is arranged on the side of the antenna structure array. The application realizes the requirements of close-range wide-angle coverage and long-distance high-precision detection, and reduces the production cost.

Description

Technical Field

[0001] This invention relates to the field of vehicle-mounted radar technology, and in particular to a forward-facing millimeter-wave radar antenna. Background Technology

[0002] In automotive millimeter-wave radar systems, waveguide antennas offer advantages over traditional printed circuit board microstrip antennas, including lower loss, higher efficiency, and wider bandwidth. Current radar antennas employ a three-layer waveguide structure, but this structure is complex, costly to manufacture, and difficult to solder. Furthermore, a single antenna type often struggles to meet the diverse needs of existing automotive radar systems for different scenarios. Summary of the Invention

[0003] To address this, the present invention provides a forward millimeter-wave radar antenna that integrates a wide-beam waveguide antenna and a narrow-beam waveguide antenna on two structural layers, thereby achieving the requirements of close-range wide-angle coverage and long-range high-precision detection, reducing production costs, and taking into account high gain, low sidelobes, and wide bandwidth performance, which is beneficial to improving the overall detection capability of vehicle-mounted radar.

[0004] To solve the above-mentioned technical problems, the present invention provides a forward millimeter-wave radar antenna, including a body and a wide-beam waveguide antenna, a narrow-beam waveguide antenna and a waveguide transmission channel integrated in the body, wherein the waveguide transmission channel includes a first waveguide transmission channel and a second waveguide transmission channel;

[0005] The wide-beam waveguide antenna includes:

[0006] A polarization conversion structure is disposed at the end of the first waveguide transmission channel to convert the horizontal polarization direction of the electromagnetic wave in the first waveguide transmission channel into the vertical polarization direction.

[0007] The antenna unit includes a first antenna radiating cavity, a first slot radiating groove, and a first open horn connected in sequence, and the polarization conversion structure is connected to the first antenna radiating cavity.

[0008] The first choke groove is disposed beside the first open horn;

[0009] The narrow-beam waveguide antenna includes:

[0010] The splitter has its input end connected to the second waveguide transmission channel to split the signal energy in the second waveguide transmission channel before transmission;

[0011] The antenna array includes several sub-antenna structure units connected to the output terminal of the splitter. Each sub-antenna structure unit includes a second antenna radiation cavity, a second slot radiation groove, and a second open horn connected in sequence.

[0012] The second choke slot is disposed on the side of the antenna structure array;

[0013] The main body includes a first structural component and a second structural component connected together. The wide-beam waveguide antenna and the narrow-beam waveguide antenna each have two parts respectively disposed on the first structural component and the second structural component. The first structural component has a waveguide transmission interface interconnected with the chip for transmitting signals from the chip to the first waveguide transmission channel and the second waveguide transmission channel, and radiating them out through the wide-beam waveguide antenna and the narrow-beam waveguide antenna respectively.

[0014] In one embodiment of the present invention, the first waveguide transmission channel includes a first waveguide transmission channel one, a first waveguide transmission channel two, and a first waveguide transmission channel three connected in sequence. The first waveguide transmission channel one extends along a first direction, the first waveguide transmission channel three extends along a second direction, and the first waveguide transmission channel two is disposed at a transitional angle between the first waveguide transmission channel one and the first waveguide transmission channel three; the first antenna radiation cavity, the first slot radiation groove, and the first open horn are arranged in sequence along a third direction.

[0015] The first antenna radiating cavity and the first open horn extend along the second direction, and a plurality of the first slot radiating grooves are distributed along the second direction.

[0016] The first direction, the second direction, and the third direction are all perpendicular to each other;

[0017] The polarization conversion structure is located at the end of the first waveguide transmission channel three.

[0018] In one embodiment of the present invention, the polarization conversion structure is located at the middle of the side of the first antenna radiating cavity; a first impedance matching structure is provided at the beginning of the first waveguide transmission channel; and a second impedance matching structure is provided in the first antenna radiating cavity near the polarization conversion structure.

[0019] In one embodiment of the present invention, the first choke groove extends along the second direction, and two first choke grooves are symmetrically arranged on both sides of the first opening horn along the first direction.

[0020] In one embodiment of the present invention, the second waveguide transmission channel includes a second waveguide transmission channel one, a second waveguide transmission channel two, and a second waveguide transmission channel three connected in sequence. The second waveguide transmission channel one and the second waveguide transmission channel three extend along a first direction, and the second waveguide transmission channel two extends along a second direction.

[0021] Several sub-antenna structural units are distributed along a first direction, and the second antenna radiating cavity, the second slot radiating groove, and the second open horn are arranged sequentially along a third direction.

[0022] The second antenna radiating cavity and the second open horn extend along the second direction, and a plurality of the second slot radiating grooves are distributed along the second direction;

[0023] The first direction, the second direction, and the third direction are perpendicular to each other.

[0024] In one embodiment of the present invention, a third impedance matching structure is provided at the bottom of the second antenna radiating cavity, and a fourth impedance matching structure is provided at the beginning of the second waveguide transmission channel.

[0025] In one embodiment of the present invention, the second choke slot extends along the second direction, and two second choke slots are symmetrically arranged on both sides of the antenna structure array along the first direction.

[0026] In one embodiment of the present invention, the splitter includes a plurality of power branches extending along a second direction, each power branch extending between two adjacent second antenna radiating cavities, and the ends of each power branch extending along both sides of a first direction as first branches and second branches, the first branches and the second branches being respectively connected to two adjacent second antenna radiating cavities.

[0027] In one embodiment of the present invention, a sixth impedance matching structure is further provided between the end of the second waveguide transmission channel three and the splitter, and a sub-channel extending along the first direction is provided between the sixth impedance matching structure and the two power branch paths, and a fifth impedance matching structure is provided on the sub-channel.

[0028] In one embodiment of the present invention, a seventh impedance matching structure and an eighth impedance matching structure are respectively provided on both sides of the end of the power branch along a third direction.

[0029] The technical solution of the present invention has the following advantages compared with the prior art:

[0030] The present invention discloses a forward millimeter-wave radar antenna that integrates a wide-beam waveguide antenna and a narrow-beam waveguide antenna on two structural layers. The wide-beam portion is mainly used for short-range, wide-area detection, while the narrow-beam portion is used for long-range, high-precision detection. Through the synergistic effect of the two, the detection performance of vehicle radar in different scenarios can be significantly improved.

[0031] Furthermore, the invention employs a two-layer structure design, which makes processing and assembly more convenient, thereby reducing production costs; by utilizing the layout of narrow-side feeding and narrow-side radiating cavity, the horizontal size of the waveguide antenna is effectively reduced, adapting to compact installation requirements; the wide-beam antenna not only has high gain, but also wide beam coverage and low sidelobes, which can meet the needs of close-range, wide-area detection; the narrow-beam antenna also has the characteristics of high gain and low sidelobes, enabling it to provide higher accuracy in long-range detection. Attached Figure Description

[0032] To make the content of this invention easier to understand, the invention will be further described in detail below with reference to specific embodiments and accompanying drawings.

[0033] Figure 1 This is a schematic diagram of the overall structure of the forward millimeter-wave radar antenna of the present invention.

[0034] Figure 2 This is a schematic diagram of the first perspective of the cross-section of the forward millimeter-wave radar antenna of the present invention.

[0035] Figure 3 This is a schematic diagram of the second perspective of the cross-section of the forward millimeter-wave radar antenna of the present invention.

[0036] Figure 4 This is a schematic diagram of the axial structure of the wide-beam waveguide antenna of the present invention.

[0037] Figure 5 This is a schematic diagram of the front view structure of the narrow beam waveguide antenna of the present invention.

[0038] Figure 6 This is a schematic diagram of the axial structure of the narrow beam waveguide antenna of the present invention.

[0039] Figure 7 This is a schematic diagram of the structure of the splitter of the present invention.

[0040] Figure 8 This is a simulation diagram of the wide-beam waveguide antenna of the present invention.

[0041] Figure 9 This is the radiation pattern of the wide-beam waveguide antenna of the present invention.

[0042] Figure 10 This is a simulation diagram of the narrow beam waveguide antenna of the present invention.

[0043] Figure 11 This is the radiation pattern of the narrow beam waveguide antenna of the present invention.

[0044] Explanation of reference numerals on the accompanying drawings:

[0045] 1. First structural component;

[0046] 2. Second structural component;

[0047] 3. Wide-beam waveguide antenna; 3-1. First antenna radiating cavity; 3-2. Second impedance matching structure; 3-3. First slot radiating groove; 3-4. First open horn; 3-5. First choke groove;

[0048] 4. Narrow beam waveguide antenna; 4a. Sub-antenna structural unit; 4-1. Second antenna radiating cavity; 4-2. Second slotted radiating groove; 4-3. Second open horn; 4-4. Second choke groove; 4-5. Third impedance matching structure;

[0049] 5. Waveguide transmission channel; 5-1. First waveguide transmission channel; 5-1a. First waveguide transmission channel one; 5-1b. First waveguide transmission channel two; 5-1c. First waveguide transmission channel three; 5-1-1. First impedance matching structure; 5-1-2. Polarization conversion structure; 5-2. Second waveguide transmission channel; 5-2a. Second waveguide transmission channel one; 5-2b. Second waveguide transmission channel two; 5-2c. Second waveguide transmission channel three; 5-2-1. Fourth impedance matching structure;

[0050] 6. Waveguide transmission interface;

[0051] 7. Branch circuit; 7-1. Fifth impedance matching structure; 7-2. Sixth impedance matching structure; 7-3. Power branch; 7-4. Seventh impedance matching structure; 7-5. Eighth impedance matching structure; 7-6. First branch; 7-7. Second branch; 7-8. Sub-channel. Detailed Implementation

[0052] The present invention will be further described below with reference to the accompanying drawings and specific embodiments, so that those skilled in the art can better understand and implement the present invention. However, the embodiments described are not intended to limit the present invention.

[0053] In this invention, when directions (up, down, left, right, front, and back) are described, it is only for the convenience of describing the technical solution of this invention, and does not indicate or imply that the technical features referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, it should not be construed as a limitation of this invention.

[0054] In this invention, "several" means one or more, "multiple" means two or more, "greater than," "less than," "exceeding," etc., are understood to exclude the stated number; "above," "below," "within," etc., are understood to include the stated number. In the description of this invention, the terms "first" and "second" are used only to distinguish technical features and should not be construed as indicating or implying relative importance, or implicitly indicating the number of indicated technical features, or implicitly indicating the order of the indicated technical features.

[0055] In this invention, unless otherwise explicitly defined, the terms "setting," "installing," and "connecting" should be interpreted broadly. For example, they can refer to a direct connection or an indirect connection through an intermediate medium; a fixed connection, a detachable connection, or an integrally formed connection; a mechanical connection, an electrical connection, or a connection capable of mutual communication; or the internal connection of two components or the interaction between two components. Those skilled in the art can reasonably determine the specific meaning of the above terms in this invention based on the specific content of the technical solution.

[0056] Reference Figures 1 to 3 As shown, a forward millimeter-wave radar antenna of the present invention includes a body and a wide-beam waveguide antenna 3, a narrow-beam waveguide antenna 4 and a waveguide transmission channel 5 integrated in the body. The waveguide transmission channel 5 includes a first waveguide transmission channel 5-1 and a second waveguide transmission channel 5-2.

[0057] The wide-beam waveguide antenna 3 includes:

[0058] A polarization conversion structure 5-1-2 is disposed at the end of the first waveguide transmission channel 5-1 and is used to convert the horizontal polarization direction of the electromagnetic wave in the first waveguide transmission channel 5-1 into the vertical polarization direction.

[0059] The antenna unit includes a first antenna radiating cavity 3-1, a first slotted radiating groove 3-3, and a first open horn 3-4 connected in sequence, and the polarization conversion structure 5-1-2 is connected to the first antenna radiating cavity 3-1.

[0060] The first choke groove 3-5 is disposed beside the first open horn 3-4;

[0061] The narrow-beam waveguide antenna 4 includes:

[0062] Splitter 7, whose input is connected to the second waveguide transmission channel 5-2, to split the signal energy in the second waveguide transmission channel 5-2 before transmission;

[0063] The antenna array includes several sub-antenna structure units 4a connected to the output terminal of the splitter 7. Each sub-antenna structure unit 4a includes a second antenna radiation cavity 4-1, a second slot radiation groove 4-2, and a second open horn 4-3 connected in sequence.

[0064] The second choke slot 4-4 is disposed on the side of the antenna structure array;

[0065] The main body includes a first structural component 1 and a second structural component 2 connected together. The wide-beam waveguide antenna 3 and the narrow-beam waveguide antenna 4 each have two parts respectively disposed on the first structural component 1 and the second structural component 2. The first structural component 1 has a waveguide transmission interface 6 interconnected with the chip, which is used to transmit signals from the chip to the first waveguide transmission channel 5-1 and the second waveguide transmission channel 5-2, and radiate them out through the wide-beam waveguide antenna 3 and the narrow-beam waveguide antenna 4 respectively.

[0066] By integrating a wide-beam waveguide antenna 3 and a narrow-beam waveguide antenna 4 on two structural components, the wide-beam part is mainly used for short-range, wide-area detection, while the narrow-beam part is used for long-range, high-precision detection. Through the synergistic effect of the two, the detection performance of vehicle radar in different scenarios can be significantly improved.

[0067] Furthermore, the invention employs a two-layer structure design, which makes processing and assembly more convenient, thereby reducing production costs; by utilizing the layout of narrow-side feeding and narrow-side radiating cavity, the horizontal size of the waveguide antenna is effectively reduced, adapting to compact installation requirements; the wide-beam antenna not only has high gain, but also wide beam coverage and low sidelobes, which can meet the needs of close-range, wide-area detection; the narrow-beam antenna also has the characteristics of high gain and low sidelobes, enabling it to provide higher accuracy in long-range detection.

[0068] Specifically, refer to Figure 4 As shown, the first waveguide transmission channel 5-1 includes a first waveguide transmission channel 1 5-1a, a first waveguide transmission channel 2 5-1b, and a first waveguide transmission channel 3 5-1c connected in sequence. The first waveguide transmission channel 1 5-1a extends along a first direction, the first waveguide transmission channel 3 5-1c extends along a second direction, and the first waveguide transmission channel 2 5-1b is inclinedly disposed between the first waveguide transmission channel 1 5-1a and the first waveguide transmission channel 3 5-1c. The first antenna radiation cavity 3-1, the first slot radiation groove 3-3, and the first open horn 3-4 are arranged in sequence along a third direction.

[0069] The first antenna radiating cavity 3-1 and the first open horn 3-4 extend along the second direction, and a plurality of the first slot radiating grooves 3-3 are distributed along the second direction;

[0070] The first direction (X), the second direction (Y), and the third direction (Z) are perpendicular to each other;

[0071] The polarization conversion structure 5-1-2 is disposed at the end of the first waveguide transmission channel 5-1c.

[0072] Specifically, the polarization conversion structure 5-1-2 is located in the middle of the side of the first antenna radiation cavity 3-1; the first end of the first waveguide transmission channel 5-1a is provided with a first impedance matching structure 5-1-1; and the first antenna radiation cavity 3-1 is provided with a second impedance matching structure 3-2 near the polarization conversion structure 5-1-2.

[0073] Specifically, the first choke groove 3-5 extends along the second direction, and the two first choke grooves 3-5 are symmetrically arranged on both sides of the first open horn 3-4 along the first direction.

[0074] Specifically, refer to Figure 5 , Figure 6 As shown, the second waveguide transmission channel 5-2 includes a second waveguide transmission channel 1 5-2a, a second waveguide transmission channel 2 5-2b, and a second waveguide transmission channel 3 5-2c connected in sequence. The second waveguide transmission channel 1 5-2a and the second waveguide transmission channel 3 5-2c extend along a first direction, and the second waveguide transmission channel 2 5-2b extends along a second direction.

[0075] Several sub-antenna structural units 4a are distributed along a first direction, and the second antenna radiating cavity 4-1, the second slot radiating groove 4-2, and the second open horn 4-3 are arranged sequentially along a third direction;

[0076] The second antenna radiating cavity 4-1 and the second open horn 4-3 extend along the second direction, and a plurality of second slot radiating grooves 4-2 are distributed along the second direction;

[0077] The first direction (X), the second direction (Y), and the third direction (Z) are perpendicular to each other.

[0078] Specifically, a third impedance matching structure 4-5 is provided at the bottom of the second antenna radiation cavity 4-1, and a fourth impedance matching structure 5-2-1 is provided at the beginning of the second waveguide transmission channel 5-2a.

[0079] Specifically, the second choke slot 4-4 extends along the second direction, and the two second choke slots 4-4 are symmetrically arranged on both sides of the antenna structure array along the first direction.

[0080] Reference Figure 7As shown, the narrow-beam waveguide antenna 4 transmits and distributes signal energy using a second waveguide transmission channel 5-2 and a splitter 7. The splitter 7 includes several power branch paths 7-3 extending along a second direction. Each power branch path 7-3 extends between two adjacent second antenna radiating cavities 4-1. The ends of each power branch path 7-3 extend along two sides of a first direction, forming a first branch 7-6 and a second branch 7-7, which are respectively connected to two adjacent second antenna radiating cavities 4-1. In this embodiment, two power branch paths 7-3 are provided, and three sub-antenna structure units 4a are provided. The splitter 7 divides the signal energy within the second waveguide transmission channel (5-2) into two parts for transmission to the narrow-beam waveguide antenna 4, and then radiates it out.

[0081] Specifically, a sixth impedance matching structure 7-2 is provided between the end of the second waveguide transmission channel 5-2c and the splitter 7. A sub-channel 7-8 extending along the first direction is provided between the sixth impedance matching structure 7-2 and the two power branch paths 7-3. A fifth impedance matching structure 7-1 is provided on the sub-channel 7-8.

[0082] Specifically, the power branch 7-3 is provided with a seventh impedance matching structure 7-4 and an eighth impedance matching structure 7-5 on both sides along the third direction at its end.

[0083] In one embodiment, the first impedance matching structure 5-1-1 to the eighth impedance matching structure 7-5 all include an arc-shaped step structure.

[0084] Reference Figure 8 As shown, the wide-beam waveguide antenna 3 has a return loss S11≤-20dB in the 76~79GHz range, indicating that the signal has good transmission performance in this frequency band.

[0085] Reference Figure 9 The diagram shows the radiation pattern of the wide-beam waveguide antenna 3. It can be seen that the antenna gain is 15.7 dBi @ 0° (the gain in the 0° direction is 15.7 dBi), and the sidelobe level is ≥ 21.7 dB.

[0086] Reference Figure 10 As shown, the narrow-beam waveguide antenna 4 has a return loss S11≤-20dB in the 76-79GHz range, indicating that the signal has good transmission performance in this frequency band.

[0087] Reference Figure 11The diagram shows the radiation pattern of the narrow-beam waveguide antenna 4. It can be seen that the antenna gain is 20.5 dBi at 0° (the gain at 0° is 20.5 dBi), and the sidelobe level is ≥18.3 dB. It features high gain and low sidelobe performance, which can improve the detection range of vehicle-mounted radar and enhance the anti-interference capability of the radar system.

[0088] Finally, it should be noted that the above specific embodiments are only used to illustrate the technical solutions of the present invention and not to limit it. Although the present invention has been described in detail with reference to examples, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the spirit and scope of the technical solutions of the present invention, and all such modifications or substitutions should be covered within the scope of the claims of the present invention.

Claims

1. A forward-looking millimeter wave radar antenna, characterized by, The body comprises a wide-beam waveguide antenna (3), a narrow-beam waveguide antenna (4) and a waveguide transmission channel (5) integrated in the body, and the waveguide transmission channel (5) comprises a first waveguide transmission channel (5-1) and a second waveguide transmission channel (5-2); The wide-beam waveguide antenna (3) comprises: A polarization conversion structure (5-1-2) is arranged at the end of the first waveguide transmission channel (5-1) and is used for converting the horizontal polarization direction of the electromagnetic wave in the first waveguide transmission channel (5-1) into the vertical polarization direction; The antenna unit comprises a first antenna radiation cavity (3-1), a first slot radiation groove (3-3) and a first open horn (3-4) connected in sequence, and the polarization conversion structure (5-1-2) is connected with the first antenna radiation cavity (3-1); A first choke groove (3-5) is arranged beside the first open horn (3-4); The narrow-beam waveguide antenna (4) comprises: A splitter (7) is connected with the second waveguide transmission channel (5-2) at the input end, so as to split and transmit the signal energy in the second waveguide transmission channel (5-2); The antenna structure array comprises a plurality of sub-antenna structure units (4a) connected with the output end of the splitter (7), and each sub-antenna structure unit (4a) comprises a second antenna radiation cavity (4-1), a second slot radiation groove (4-2) and a second open horn (4-3) connected in sequence; A second choke groove (4-4) is arranged beside the antenna structure array; The body comprises a first structure (1) and a second structure (2) connected with each other, two parts of the wide-beam waveguide antenna (3) and the narrow-beam waveguide antenna (4) are arranged on the first structure (1) and the second structure (2) respectively, a waveguide transmission interface (6) is arranged on the first structure (1) and is connected with a chip, so as to transmit the signal from the chip to the first waveguide transmission channel (5-1) and the second waveguide transmission channel (5-2) and radiate out through the wide-beam waveguide antenna (3) and the narrow-beam waveguide antenna (4) respectively.

2. A forward-looking millimeter wave radar antenna according to claim 1, characterized in that The first waveguide transmission channel (5-1) comprises a first waveguide transmission channel one (5-1a), a first waveguide transmission channel two (5-1b) and a first waveguide transmission channel three (5-1c) connected in sequence, the first waveguide transmission channel one (5-1a) extends along a first direction, the first waveguide transmission channel three (5-1c) extends along a second direction, and the first waveguide transmission channel two (5-1b) is transitionally and obliquely arranged between the first waveguide transmission channel one (5-1a) and the first waveguide transmission channel three (5-1c); the first antenna radiation cavity (3-1), the first slot radiation groove (3-3) and the first open horn (3-4) are arranged in sequence along a third direction. The first antenna radiation cavity (3-1) and the first open horn (3-4) extend along the second direction, and the first slit radiation groove (3-3) is distributed along the second direction. The first direction, the second direction and the third direction are perpendicular to each other. The polarization conversion structure (5-1-2) is arranged at the end of the first waveguide transmission channel three (5-1c).

3. A forward-looking millimeter wave radar antenna according to claim 2, characterized in that The polarization conversion structure (5-1-2) is located at the middle position of the side of the first antenna radiation cavity (3-1), the first end of the first waveguide transmission channel one (5-1a) is provided with a first impedance matching structure (5-1-1), and the second impedance matching structure (3-2) is arranged at the position close to the polarization conversion structure (5-1-2) of the first antenna radiation cavity (3-1).

4. A forward-looking millimeter wave radar antenna according to claim 2, characterized in that, The first choke groove (3-5) extends along the second direction, and the two first choke grooves (3-5) are symmetrically arranged on the two sides of the first open horn (3-4) along the first direction.

5. A forward-looking millimeter wave radar antenna according to claim 1, wherein, The second waveguide transmission channel (5-2) comprises a second waveguide transmission channel one (5-2a), a second waveguide transmission channel two (5-2b) and a second waveguide transmission channel three (5-2c) connected in sequence, the second waveguide transmission channel one (5-2a) and the second waveguide transmission channel three (5-2c) extend along the first direction, and the second waveguide transmission channel two (5-2b) extends along the second direction. The second antenna radiation cavity (4-1), the second slit radiation groove (4-2) and the second open horn (4-3) are arranged in sequence along the third direction. The second antenna radiation cavity (4-1) and the second open horn (4-3) extend along the second direction, and the second slit radiation groove (4-2) is distributed along the second direction. The first direction, the second direction and the third direction are perpendicular to each other.

6. A forward-looking millimeter wave radar antenna according to claim 5, characterized in that The bottom of the second antenna radiation cavity (4-1) is provided with a third impedance matching structure (4-5), and the first end of the second waveguide transmission channel one (5-2a) is provided with a fourth impedance matching structure (5-2-1).

7. A forward-looking millimeter wave radar antenna according to claim 5, characterized in that, The second choke groove (4-4) extends along the second direction, and the two second choke grooves (4-4) are symmetrically arranged on the two sides of the antenna structure array along the first direction.

8. A forward-looking millimeter wave radar antenna according to claim 5, characterized in that, The splitter (7) comprises a plurality of power division branches (7-3) extending along the second direction, each power division branch (7-3) extends between adjacent two second antenna radiation cavities (4-1), and the end of each power division branch (7-3) extends along the first direction. The first branch (7-6) and the second branch (7-7) on the two sides, the first branch (7-6) and the second branch (7-7) are connected with adjacent two second antenna radiation cavities (4-1) respectively.

9. A forward-looking millimeter wave radar antenna according to claim 8, characterized in that, The end of the second waveguide transmission channel three (5-2c) and the splitter (7) are further provided with a sixth impedance matching structure (7-2), and the sixth impedance matching structure (7-2) and the two power division branches (7-3) are provided with a branch channel (7-8) extending in a first direction, and the branch channel (7-8) is provided with a fifth impedance matching structure (7-1).

10. A forward-looking millimeter wave radar antenna according to claim 8, characterized in that, The ends of the power division branches (7-3) are respectively provided with a seventh impedance matching structure (7-4) and an eighth impedance matching structure (7-5) on both sides in a third direction.

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