Waveguide antenna for vehicle-mounted 4D millimeter wave radar

Abstract

The invention discloses a waveguide antenna for a vehicle-mounted 4D millimeter wave radar, which comprises a waveguide antenna body, a zigzag waveguide duct is formed in the waveguide antenna body, the waveguide duct is provided with an open end and a closed end, the open end of the waveguide duct penetrates through one end face of the waveguide antenna body, and the closed end of the waveguide duct penetrates through the other end face of the waveguide antenna body. A plurality of waveguide slots which are arranged in the same direction are formed in the front surface of the waveguide antenna body, the waveguide slots are communicated with the waveguide hole channel, and the plurality of waveguide slots are arranged at equal intervals. According to the invention, the problems that the polarization purity of the antenna is easily reduced and the phase center is unstable due to the inclined slot of the narrow-side slot antenna when the 4D millimeter wave radar adopts the traditional narrow-side slot antenna are solved. In addition, due to the introduction of the horn-shaped radiation structure, larger antenna gain can be realized with a small number of slots.

Description

Technical Field

[0001] The present invention relates to the technical field of waveguide antennas, and more particularly to a waveguide antenna for a vehicle-mounted 4D millimeter-wave radar. Background Art

[0002] To help achieve higher levels of autonomous driving, the concept of 4D millimeter-wave radar is gaining popularity. In addition to retaining the three-dimensional detection capabilities of traditional millimeter-wave radar—range, speed, and direction—4D millimeter-wave radar also adds the ability to analyze target altitude. Consequently, 4D millimeter-wave radar places higher demands on antenna performance and array layout.

[0003] Waveguide antennas have the advantages of low loss, high gain, high power handling capability, and flexible three-dimensional spatial layout capabilities, making them the first choice for 4D millimeter-wave radars.

[0004] The frequency band of the vehicle-mounted millimeter-wave radar is 77GHz, and the corresponding wavelength is about 3.9mm. This means that the waveguide antenna in this frequency band has very high requirements for processing accuracy. According to the distribution characteristics of the current in the waveguide, there is no transverse current at the center of the wide side. Therefore, the method of cutting the waveguide at the center of the wide side can effectively avoid cutting the current, thereby reducing the requirements for processing accuracy of this part. In addition, in order to avoid the introduction of grating lobes, the slot distribution of the traditional narrow-side slot antenna 3 generally adopts the method of rotating the slot alternately left and right so that the slot spacing is distributed in a half-waveguide wavelength distribution (such as Figure 1 shown).

[0005] However, this approach has two significant drawbacks:

[0006] The presence of the slanted slot E will destroy the symmetry of the electromagnetic field in the waveguide, making it easy for the electromagnetic wave to generate an electric field component perpendicular to the main polarization direction during the radiation process, resulting in cross-polarization and reducing the polarization purity; the inclination angle and position deviation of the slanted slot E will cause the phases of the electromagnetic waves radiated from each slanted slot to be inconsistent, thereby causing the phase center to move.

[0007] Furthermore, for radars that detect targets at long distances, greater antenna gain is essential. Traditional narrow-slot antennas typically increase gain by adding slots, which inevitably increases the antenna's physical length. When the application scenario places strict restrictions on radar size, this gain-boosting approach significantly increases the complexity of the array layout. This conflict is particularly pronounced when miniaturization is a requirement. Summary of the Invention

[0008] To solve the above-mentioned problems in the prior art, the present invention provides a waveguide antenna for a vehicle-mounted 4D millimeter-wave radar, so as to solve the problem that when a 4D millimeter-wave radar adopts a traditional narrow-side slot antenna, the slanted slot of the narrow-side slot antenna easily reduces the polarization purity of the antenna, resulting in an unstable phase center, and the contradiction between the increase in the number of slots to increase the gain, thereby increasing the physical length of the antenna and the miniaturization of the array design.

[0009] To achieve the above objectives, a waveguide antenna for a vehicle-mounted 4D millimeter-wave radar is provided, comprising a waveguide antenna body, wherein a tortuous waveguide channel is formed in the waveguide antenna body, wherein the waveguide channel has an open end and a closed end, and the open end of the waveguide channel passes through an end face of the waveguide antenna body, and a front face of the waveguide antenna body is formed with a plurality of waveguide slots arranged in the same direction, wherein the waveguide slots are connected to the waveguide channel, and the plurality of waveguide slots are arranged at equal intervals.

[0010] Furthermore, it also includes a horn antenna, which is connected to the waveguide slot.

[0011] Furthermore, a horn hole connected to the waveguide slot is formed in the horn antenna, and the inner wall of the horn hole is stepped so that the inner diameter of the horn hole gradually increases from one end of the horn hole close to the waveguide slot to the other end of the horn hole away from the waveguide slot.

[0012] Furthermore, the horn antenna and the waveguide antenna body are integrally formed.

[0013] Furthermore, the waveguide channel is wavy.

[0014] Furthermore, the crests and troughs of the waveguide channel are respectively curved.

[0015] The present invention provides a vehicle-mounted radar, comprising a waveguide antenna for a vehicle-mounted 4D millimeter-wave radar.

[0016] The beneficial effects of the present invention lie in that the waveguide antenna for automotive 4D millimeter-wave radar employs a curved waveguide channel to wind the waveguide. By adjusting the waveguide channel length (i.e., the waveguide path length), the electromagnetic waves remain in phase at the waveguide slots on the narrow side of the waveguide. Because the opening directions of the waveguide slots (i.e., the outer slot openings) are consistent and the structure is symmetrical, the antenna's polarization purity and phase center stability are improved. Furthermore, the horn-shaped structure achieves progressive guidance and beam focusing of electromagnetic waves, enabling a radiation gain higher than that of traditional narrow-side slot antennas using only a small number of slot elements. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1The figure is a schematic structural diagram of a narrow-side slot antenna in the prior art.

[0018] Figure 2 This is a schematic structural diagram of a waveguide antenna for a vehicle-mounted 4D millimeter-wave radar according to Example 1 of the present invention.

[0019] Figure 3 This is a schematic structural diagram of the waveguide antenna body of Example 1 of the present invention.

[0020] Figure 4 This is a top view of the waveguide antenna body of embodiment 1 of the present invention.

[0021] Figure 5 This is a schematic structural diagram of the horn antenna according to embodiment 1 of the present invention.

[0022] Figure 6 1 is a top view of the horn antenna according to embodiment 1 of the present invention.

[0023] Figure 7 2 is a cross-sectional view of the horn antenna according to embodiment 1 of the present invention.

[0024] Figure 8 This is a schematic structural diagram of a waveguide antenna for a vehicle-mounted 4D millimeter-wave radar according to Example 2 of the present invention.

[0025] Figure 9 This is a schematic structural diagram of the waveguide antenna body of Example 2 of the present invention.

[0026] Figure 10 This is a top view of the waveguide antenna body of embodiment 2 of the present invention.

[0027] Reference numerals:

[0028] Waveguide antenna body 1, longitudinal section A, transverse section B, connecting section C, waveguide slot D, horn antenna 2, horn hole 20, inner wall 21, narrow side slot antenna 3, oblique slot E, transition section F. DETAILED DESCRIPTION

[0029] In order to make the purpose, scheme and advantages of the present invention clearer, the specific structure and working principle of the present invention are described in more detail below with reference to the accompanying drawings. The embodiments mentioned are only used to explain the present invention and are not limited to the embodiments and are not used to limit the scope of application of the present invention.

[0030] The following content is intended to enable the public to have a clearer understanding of the present invention. For those skilled in the art working in the relevant field, the present invention can be clearly understood even without the following detailed description.

[0031] Example 1

[0032] Reference Figures 2 to 7As shown, the present invention provides a waveguide antenna for a vehicle-mounted 4D millimeter wave radar, comprising a waveguide antenna body 1. A tortuous waveguide channel is formed in the waveguide antenna body 1.

[0033] In this embodiment, the waveguide antenna body 1 is in a rectangular parallelepiped shape, and the waveguide channel is entirely arranged along the length direction of the waveguide antenna body 1 .

[0034] The waveguide channel has an open end and a closed end. The open end of the waveguide channel extends through the end surface of one end of the waveguide antenna body. A plurality of waveguide slots D are formed on the front surface of the waveguide antenna body 1. The plurality of waveguide slots D are arranged in the same direction. The plurality of waveguide slots D are of equal size and are spaced evenly apart.

[0035] As a preferred embodiment, the waveguide antenna for the vehicle-mounted 4D millimeter wave radar of the present invention further includes a horn antenna 2. The horn antenna 2 is connected to the waveguide slot D. The number of horn antennas is adapted to the number of waveguide slots.

[0036] In this embodiment, a horn hole 20 is formed in the horn antenna 2 and is connected to the waveguide slot D. The inner wall 21 of the horn hole is stepped so that the inner diameter of the horn hole gradually increases from one end of the horn hole closer to the waveguide slot to the other end of the horn hole farther from the waveguide slot.

[0037] The inner wall 21 of the horn hole 20 is stepped, and the length, width, and height of each step can be optimized as independent variables. Adjusting these variables can optimize the overall antenna performance, including but not limited to improving impedance matching, reducing reflection loss, optimizing the radiation pattern, and suppressing sidelobe levels.

[0038] The end of the horn hole close to the waveguide slot is connected to the waveguide slot. The opening of the horn hole is in the shape of a long strip. The horn hole and the waveguide slot are arranged in the same direction. In this embodiment, the horn hole is arranged along the width direction of the waveguide antenna body. Figures 5 to 7 As shown, the inner walls of the horn hole on opposite sides in the width direction are stepped so that the width of the horn hole gradually increases from the bottom of the waveguide slot toward the slot opening of the waveguide slot. The length of the horn hole does not change.

[0039] In this embodiment, the waveguide channel is wavy (ie, similar to a sine curve).

[0040] Specifically, the waveguide channel includes a longitudinal section A, a plurality of transverse sections B and a plurality of connecting sections C.

[0041] The longitudinal section A is provided at one end of the waveguide antenna body 1 along the length direction of the waveguide antenna body 1 , and a first end of the longitudinal section A passes through an end surface of one end of the waveguide antenna body 1 .

[0042] Multiple transverse segments B are arranged at intervals in the middle of the waveguide antenna body 1 along the length direction of the waveguide antenna body 1, and a single transverse segment B is arranged along the width direction of the waveguide antenna body 1. Multiple transverse segments B are connected in series through the connecting segment C to form a curved channel, and the second end of the longitudinal segment A is connected to one end of the curved channel.

[0043] The waveguide antenna body 1 is formed with a plurality of waveguide slots D. The positions of the waveguide slots D correspond to the positions of the transverse sections B. The waveguide slots D are connected to the transverse sections B and are arranged in the same direction as the transverse sections B.

[0044] In this embodiment, each transverse segment B is correspondingly provided with a waveguide slot D. The length of the waveguide slot D is smaller than the length of the transverse segment B, and the waveguide slot D is centrally provided in the middle of the transverse segment B.

[0045] The entire waveguide channel is filled with a medium. Electromagnetic waves can be transmitted in the medium. In this embodiment, the medium is air. The size of the waveguide channel meets the frequency requirements of the waveguide antenna. Specifically, the frequency band of the waveguide antenna for the vehicle-mounted 4D millimeter wave radar of the present invention is 77GHz, and the corresponding wavelength is about 3.9mm. Figure 4 As shown, Figure 4 The hollow arrows in the figure indicate the direction of signal transmission in the waveguide channel. The cross-section of the waveguide channel is rectangular. The top and bottom surfaces of the waveguide channel are narrow, with the waveguide slot located on these narrow surfaces. The left and right sides of the waveguide channel are wide.

[0046] In this embodiment, the waveguide antenna body 1 is made of metal or plastic with a conductive coating. The waveguide antenna body 1 can be divided into two layers, each processed separately. The horn antenna is integrally formed with the upper layer of the waveguide antenna body. Metal waveguide antenna bodies 1 can be manufactured using casting, 3D printing, or CNC machining, while plastic waveguide antenna bodies 1 can be manufactured using injection molding, 3D printing, or CNC machining before being coated with a metal layer. The upper and lower layers of the waveguide antenna body 1 can be connected using processes such as screwing, bonding, or welding.

[0047] The waveguide antenna for automotive 4D millimeter-wave radar of this invention utilizes a curved waveguide channel to wind the waveguide. By adjusting the waveguide channel length (i.e., the waveguide path length), the electromagnetic waves remain in phase at each waveguide slot on the narrow side of the waveguide. Because the opening directions of each waveguide slot (i.e., the outer slot openings) are consistent and the structure is symmetrical, the antenna's polarization purity and phase center stability are improved.

[0048] Traditional narrow side slot antennas (such as Figure 1) To achieve greater gain, more slot structures need to be added. The increase in slots will not only reduce the bandwidth of the antenna, but also reduce the beam width on the pitch plane, that is, reduce the detection range of the target height dimension. In addition, an overly long antenna will also limit the flexibility of the millimeter-wave radar antenna array layout. The waveguide antenna for the vehicle-mounted 4D millimeter-wave radar of the present invention adopts the form of a horn-shaped waveguide slot, which effectively expands the antenna gain while setting a smaller number of waveguide slots. In addition, the inner wall of the waveguide slot of the waveguide antenna for the vehicle-mounted 4D millimeter-wave radar of the present invention adopts the form of a step, and the length, width and height of each step can also be used as adjustment parameters for antenna gain, impedance matching, standing wave ratio, sidelobe level suppression, polarization purity, etc., to further optimize the antenna performance.

[0049] The present invention provides a vehicle-mounted radar including the above-mentioned waveguide antenna for the vehicle-mounted 4D millimeter-wave radar.

[0050] Example 2

[0051] Reference Figures 8 to 10 As shown, the present invention provides a waveguide antenna for a vehicle-mounted 4D millimeter wave radar, comprising a waveguide antenna body 1 and a horn antenna 2. A waveguide channel is formed in the waveguide antenna body 1.

[0052] The waveguide antenna for the vehicle-mounted 4D millimeter-wave radar of this embodiment differs from that of Embodiment 1 in the structural form of the connecting section C, that is, the crests and troughs of the waveguide channel are curved.

[0053] Specifically, in this embodiment, refer to Figure 10 As shown, the middle portion of the connecting section C bends toward the space between the two adjacent transverse sections B. The connecting section C is generally U-shaped. The longitudinal section A is aligned with the middle portion of the transverse section B. The longitudinal section A is connected to one end of the curved channel via an arc-shaped transition section F.

[0054] The waveguide antenna for the vehicle-mounted 4D millimeter-wave radar of the present invention adopts a waveguide channel composed of a U-shaped connecting section, which can further narrow the overall width of the antenna and can also be wound using a waveguide with a smaller narrow side size.

[0055] The above description is merely a preferred embodiment of the present invention and is not intended to limit the scope of the present invention. Various modifications are possible. In other words, any simple, equivalent changes and modifications made in accordance with the claims and description of the present invention are within the scope of protection of the patent claims. Anything not fully described in this invention constitutes conventional technology.

Claims

1. A waveguide antenna for a vehicle-mounted 4D millimeter-wave radar, characterized in that: The invention comprises a waveguide antenna body, wherein a tortuous waveguide channel is formed in the waveguide antenna body, wherein the waveguide channel has an open end and a closed end, wherein the open end of the waveguide channel passes through an end face of the waveguide antenna body, and wherein a plurality of waveguide slots arranged in the same direction are formed on the front face of the waveguide antenna body, wherein the waveguide slots are connected to the waveguide channel, and wherein the plurality of waveguide slots are arranged at equal intervals.

2. The waveguide antenna for vehicle-mounted 4D millimeter wave radar according to claim 1, characterized in that: Also included is a horn antenna connected to the waveguide slot.

3. The waveguide antenna for vehicle-mounted 4D millimeter wave radar according to claim 2, characterized in that: A horn hole connected to the waveguide slot is formed in the horn antenna, and the inner wall of the horn hole is stepped so that the inner diameter of the horn hole gradually increases from one end of the horn hole close to the waveguide slot to the other end of the horn hole away from the waveguide slot.

4. The waveguide antenna for vehicle-mounted 4D millimeter wave radar according to claim 3, characterized in that: The horn antenna and the waveguide antenna body are integrally formed.

5. The waveguide antenna for vehicle-mounted 4D millimeter-wave radar according to claim 1, characterized in that: The waveguide channel is wavy.

6. The waveguide antenna for vehicle-mounted 4D millimeter wave radar according to claim 5, characterized in that: The crests and troughs of the waveguide channel are respectively in the shape of curves.

7. A vehicle-mounted radar, characterized in that: It comprises a waveguide antenna for a vehicle-mounted 4D millimeter-wave radar as claimed in any one of claims 1 to 6.

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