Bent cavity waveguide antenna suitable for millimeter wave radar

Abstract

The utility model discloses a bending cavity waveguide antenna suitable for a millimeter wave radar. The bending cavity waveguide antenna comprises a plurality of radiation holes, a first choke groove, a second choke groove and a waveguide cavity, the projection shape of the waveguide cavity on the magnetic field plane comprises a wavy bending shape; the first choke groove and the second choke groove are respectively positioned on two sides of the plurality of radiation holes; and the radiation hole is communicated with the waveguide cavity. According to the utility model, through the design of the waveguide cavity with the bend, radiation holes are collinearly arranged in a row, electromagnetic waves are efficiently radiated, inclined surface waves generated by splitting of grating lobes and side lobes are avoided, the E-surface wave beam width is expanded, the size is small, the antenna is easy to process, a power divider is not needed for feeding, the flexibility of antenna layout is improved, and the antenna is suitable for large-scale popularization and application. The method has the feasibility of large-scale mass production, and the value range of key parameters is suitable for various frequency bands.

Description

Technical Field

[0001] This invention belongs to the field of waveguide antenna technology, and particularly relates to a bent cavity waveguide antenna suitable for millimeter-wave radar. Background Technology

[0002] 4D imaging radar technology not only surpasses the technical limitations of traditional radar but also brings unprecedented innovative opportunities to assisted driving with its high-precision, real-time 3D spatial imaging and environmental perception capabilities. Based on 4D millimeter-wave radar, the biggest breakthrough of 4D millimeter-wave radar compared to traditional 3D millimeter-wave radar lies in the addition of height-dimensional information. Traditional 3D millimeter-wave radar can only detect distance, speed, and horizontal angle, making it difficult to determine whether a stationary object is on the ground or in the air. When encountering scenarios such as manhole covers, speed bumps, and overpasses, it cannot accurately measure the height data of objects, easily leading to frequent braking in autonomous driving. 4D millimeter-wave radar forms a virtual aperture through longitudinal antenna arrays and MIMO (multiple-in, multiple-out) antenna technology, greatly improving vertical resolution and thus constructing denser point cloud data, enabling more accurate detection and identification of target objects. Furthermore, 4D imaging radar is less affected by rain and fog, and therefore is widely used in the field of automotive assisted driving, complementing cameras and lidar to improve the reliability of assisted driving systems.

[0003] Currently, 4D imaging radar antennas are transitioning from microstrip antennas to waveguide antennas. Traditional rectangular waveguide antennas employ a staggered arrangement, with radiating apertures on the wider side radiating to radiate energy from the waveguide cavity into free space. When the number of antenna elements is small, this design of staggered radiating apertures on both sides of the waveguide antenna's central axis can easily lead to beam sidelobe splitting, subsequently generating oblique surface waves on the antenna surface, interfering with the elevation and angle measurement performance of millimeter-wave radar. Simultaneously, the staggered distribution of radiating apertures also reduces the beamwidth in the magnetic field plane (E-plane), degrading the radar's detection performance against targets at large angles.

[0004] Arranging the radiating apertures collinearly in a single column can effectively solve the aforementioned problems, but this collinear arrangement places higher demands on structural design and manufacturing. For example, patent CN119518272A discloses a vehicle-mounted radar waveguide antenna structure. This antenna structure uses three 1-to-2 power dividers to form a 1-to-4 power divider for antenna feeding, achieving a linear array of four radiating apertures arranged in a single column. However, the three 1-to-2 power dividers occupy a large space, posing a significant challenge to antenna layout and causing additional energy loss. Optimizing the structure while arranging the radiating apertures collinearly in a single column, and avoiding grating lobes, is an important research direction for rectangular waveguide antennas. Utility Model Content

[0005] The technical problem to be solved by this utility model is to overcome the above-mentioned defects in the prior art and provide a bent cavity waveguide antenna suitable for millimeter-wave radar, including a plurality of radiation holes arranged in a row, a first choke slot, a second choke slot, and a waveguide cavity; the projection shape of the waveguide cavity on the magnetic field plane includes a wavy bent shape; the first choke slot and the second choke slot are respectively located on both sides of the plurality of radiation holes; the radiation holes are connected to the waveguide cavity.

[0006] Preferably, the waveguide includes an upper waveguide structure and a lower waveguide structure; the plurality of radiation holes, the first choke slot, and the second choke slot are disposed on the upper waveguide structure; the upper waveguide structure is provided with a first waveguide channel, the lower waveguide structure is provided with a second waveguide channel, and the waveguide cavity is composed of the first waveguide channel and the second waveguide channel.

[0007] Preferably, the wavy bend includes rounded corners or angles at the bends.

[0008] Preferably, 0.04A≤D≤0.4A; where D is the distance between the geometric center of the radiation aperture and the central axis of the waveguide cavity, and A is the width of the waveguide cavity.

[0009] Preferably, 0.05λg≤W≤0.4λg; where W is the width of the radiating aperture and λg is the waveguide wavelength corresponding to the bent cavity waveguide antenna suitable for millimeter-wave radar.

[0010] Preferably, 0.25λg≤L≤0.75λg; where L is the length of the radiation aperture.

[0011] Preferably, the shape of the radiation aperture includes at least one of a rectangle, a rounded rectangle, an ellipse, and a trapezoid.

[0012] Preferably, the shapes of the first choke groove and the second choke groove include at least one of rectangle, rounded rectangle, ellipse, and trapezoid.

[0013] Preferably, the materials of the upper waveguide structure and the lower waveguide structure include metallic materials.

[0014] Preferably, the metal material is obtained by computer numerical control machining or by injection molding and plastic metallization process.

[0015] The significant advantages of this invention are as follows: It provides a bent cavity waveguide antenna suitable for millimeter-wave radar. Through the design with a bent waveguide cavity, the radiating apertures are arranged collinearly in a row, and these apertures can be excited in phase, enabling efficient electromagnetic wave radiation. The design, based on the center-to-center spacing of the radiating apertures corresponding to the half-waveguide wavelength, avoids oblique surface waves caused by grating lobe and sidelobe splitting, facilitating the expansion of the E-plane beamwidth. Furthermore, it is compact, easy to manufacture, and does not require a power divider for feeding, improving the flexibility of antenna layout and making mass production feasible. In addition, the key parameters all conform to the value range of standard waveguides, making this waveguide antenna applicable to various frequency bands. Attached Figure Description

[0016] Figure 1 This is a perspective view of the bent cavity waveguide antenna suitable for millimeter-wave radar according to Embodiment 1 of this utility model.

[0017] Figure 2 This is a perspective view of a bent cavity waveguide antenna suitable for millimeter-wave radar according to Embodiment 1 of this utility model.

[0018] Figure 3 This is a perspective view of the upper waveguide structure in the bent cavity waveguide antenna suitable for millimeter-wave radar according to Embodiment 1 of this utility model.

[0019] Figure 4 This is a perspective view of the lower waveguide structure in the bent cavity waveguide antenna suitable for millimeter-wave radar according to Embodiment 1 of this utility model.

[0020] Figure 5 This is a top view of the bent cavity waveguide antenna suitable for millimeter-wave radar according to Embodiment 1 of this utility model.

[0021] Figure 6 This is a perspective view of the waveguide cavity in the bent cavity waveguide antenna suitable for millimeter-wave radar according to Embodiment 1 of this utility model.

[0022] Figure 7 This is a top view of the waveguide cavity in the bent cavity waveguide antenna suitable for millimeter-wave radar according to Embodiment 1 of this utility model.

[0023] Figure 8 This is a schematic diagram of the simulation results of the return loss of the bent cavity waveguide antenna suitable for millimeter-wave radar according to Embodiment 1 of this utility model.

[0024] Figure 9 This is a schematic diagram of the radiation pattern simulation results of the bent cavity waveguide antenna suitable for millimeter-wave radar according to Embodiment 1 of this utility model. Detailed Implementation

[0025] The reference to "embodiment" in this application means that a specific feature, structure, or characteristic described in connection with an embodiment may be included in at least one embodiment of this application. The appearance of this phrase in various places in the specification does not necessarily refer to the same embodiment, nor is it a separate or alternative embodiment mutually exclusive with other embodiments. It will be explicitly and implicitly understood by those skilled in the art that the embodiments described in this application can be combined with other embodiments. It should be understood that the terms "system," "apparatus," "unit," and / or "module" as used herein are used to distinguish different levels of different components, elements, parts, portions, or assemblies. However, if other words can achieve the same purpose, they may be replaced by other expressions. As shown in this specification, unless the context clearly indicates otherwise, words such as "a," "an," "an," and / or "the" are not specifically singular and may also include plural. Generally speaking, the terms "comprising" and "including" only indicate the inclusion of expressly identified steps and elements, which do not constitute an exclusive list, and a method or apparatus may also include other steps or elements.

[0026] Example 1

[0027] See Figure 1-9 As shown, this embodiment specifically provides a bent cavity waveguide antenna suitable for millimeter-wave radar, including a plurality of radiation holes 31-34 arranged in a row, a first choke slot 51, a second choke slot 52, and a waveguide cavity 4; the projection shape of the waveguide cavity 4 in the H-plane includes a wavy bent shape; specifically, the wavy bent shape can be a plurality of "V" shapes, "U" shapes, or combinations thereof, such as "W" shapes or "S" shapes. The aforementioned examples of shapes are only used to illustrate the wavy bent shape of the waveguide cavity 4 and do not limit the concept of this utility model.

[0028] The first choke slot 51 and the second choke slot 52 are located on both sides of a plurality of radiation holes 31-34, respectively; the radiation holes 31-34 are connected to the waveguide cavity 4. The bent cavity waveguide antenna suitable for millimeter-wave radar in this embodiment can be provided with a plurality of radiation holes. For ease of explanation, four radiation holes 31-34 are used in the description. Those skilled in the art will know that the specific shape, arrangement and number of radiation holes shown in the drawings do not constitute any limitation on this utility model.

[0029] As a preferred embodiment, the bent cavity waveguide antenna suitable for millimeter-wave radar includes an upper waveguide structure 1 and a lower waveguide structure 2; a plurality of radiation holes 31-34, a first choke slot 51 and a second choke slot 52 are disposed on the upper waveguide structure 1; the upper waveguide structure 1 is provided with a first waveguide channel 6, the lower waveguide structure 2 is provided with a second waveguide channel 7, and the waveguide cavity 4 is composed of the first waveguide channel 6 and the second waveguide channel 7.

[0030] In this embodiment, the waveguide cavity 4 is formed by splicing an upper waveguide structure 1 and a lower waveguide structure 2. Several radiation holes 31-34 are disposed on the upper waveguide structure 1. The first waveguide channel 6 and the second waveguide channel 7 form the waveguide cavity 4 for transmitting electromagnetic waves. It can be understood that, preferably, the second waveguide channel 7 is a bent semi-open cavity and its projection plane on the H plane is the same as that of the first waveguide channel 6. For ease of explanation, the height of the waveguide cavity 4 is B and the width is A.

[0031] As a preferred embodiment, the wavy bend includes rounded corners or angles at the bends.

[0032] In a preferred embodiment, 0.04A≤D≤0.4A; where D is the distance between the geometric center of the radiation apertures 31 to 34 and the central axis of the waveguide cavity 4, and A is the width of the waveguide cavity 4.

[0033] In a preferred embodiment, 0.05λg≤W≤0.4λg; where W is the width of the radiation aperture 31 to 34, and λg is the waveguide wavelength corresponding to the bent cavity waveguide antenna suitable for millimeter-wave radar.

[0034] In a preferred embodiment, 0.25λg≤L≤0.75λg; where L is the length of the radiation holes 31 to 34.

[0035] In a preferred embodiment, the shape of the radiation holes 31 to 34 includes at least one of rectangle, rounded rectangle, ellipse, and trapezoid.

[0036] In a preferred embodiment, the first choke groove 51 and the second choke groove 52 include at least one of the following shapes: rectangular, rounded rectangle, ellipse, and trapezoid.

[0037] In a preferred embodiment, the upper waveguide structure 1 and the lower waveguide structure 2 are made of metallic materials. Preferably, the metallic materials are manufactured by computer numerical control (CNC) machining or by injection molding and plastic metallization. Specifically, the upper waveguide structure 1 and the lower waveguide structure 2 are manufactured by CNC machining of metal, or by injection molding and plastic metallization.

[0038] Preferably, when the height of the first waveguide channel 6 is H1 and the width is A, the value of H1 can be in the range of 0 to B; further, when the height of the second waveguide channel 7 is H2 and the width is also A, the value of H2 can be in the range of B to H1.

[0039] Preferably, the length and width of the several radiating holes can be different, the spacing between each radiating hole can be adjusted, and the offset of the geometric center of the several radiating holes from the central axis of the waveguide cavity at their location can also be different. The above adjustments can be made according to the preset waveguide effect.

[0040] Preferably, the length, width, and depth of the first choke slot 51 and the second choke slot 52 can take different values, thereby achieving adjustment of the beam angle. The spacing between the first choke slot 51, the second choke slot 52, and the plurality of radiation holes can all be adjusted.

[0041] To illustrate the bent cavity waveguide antenna suitable for millimeter-wave radar in this embodiment, specific examples are provided below. Those skilled in the art will understand that the specific parameters involved in these examples do not constitute a limitation on this invention.

[0042] like Figure 1-6 The diagram shows a bent cavity waveguide antenna suitable for millimeter-wave radar, comprising an upper waveguide structure 1 and a lower waveguide structure 2 placed vertically. The upper waveguide structure 1 is provided with a first radiation aperture 31, a second radiation aperture 32, a third radiation aperture 33, a fourth radiation aperture 34, a first choke slot 51, a second choke slot 52, and a first waveguide channel 6. The radiation apertures 31 to 34 are arranged collinearly in a row. The first choke slot 51 and the second choke slot 52 are distributed on both sides of the radiation apertures 31 to 34. The first waveguide channel 6 is a bent semi-open cavity, and its cross-section in the H-plane, i.e., its projection, presents as a combination of several V-shapes.

[0043] The lower waveguide structure 2 is provided with a second waveguide channel 7. The second waveguide channel 7 has the same H-plane cross-section as the first waveguide channel 6. The first waveguide channel 6 and the second waveguide channel 7 form a waveguide cavity 4 for transmitting electromagnetic waves. The height of the waveguide cavity 4 is B and the width is A. The value of B ranges from 0.25 times the 77GHz waveguide wavelength λg to 0.45 times the 77GHz waveguide wavelength λg, and the value of A ranges from 0.5 times the 77GHz waveguide wavelength λg to 0.9 times the 77GHz waveguide wavelength λg.

[0044] Four radiating apertures 31-34 are designed as rounded rectangles. The geometric centers of each aperture 31-34 are offset from the central axis of the waveguide cavity 4 at which they are located. This offset is the distance projected onto the H-plane. The offset of the geometric center of the first radiating aperture 31 from the central axis of the waveguide cavity 4 is defined as D1 (D1 > 0). Similarly, the offset of the geometric center of the second radiating aperture 32 from the central axis of the waveguide cavity 4 at its location is -D2 (D2 > 0). The offsets of the geometric centers of the third and fourth radiating apertures 33 and 34 from the central axis of the waveguide cavity at their locations are D3 (D3 > 0) and -D4 (D4 > 0), respectively. The values ​​of D1, D2, D3, and D4 range from 0.04A to 0.4A, thus achieving in-phase excitation of the four radiating apertures.

[0045] like Figure 7 As shown, the geometric center distances between each pair of the first radiation hole 31, the second radiation hole 32, the third radiation hole 33, and the fourth radiation hole 34 are S1, S2, and S3, respectively, where the value of S1 is 2.63 mm, the value of S2 is 2.54 mm, and the value of S3 is 2.8 mm.

[0046] The distance from the geometric center of the fourth radiation aperture 34 to the end of the waveguide cavity 4 furthest from the feed port is S4. The value of S4 ranges from 0.4 times the 77GHz waveguide wavelength λg to 0.6 times the 77GHz waveguide wavelength λg.

[0047] Preferably, the width of the radiation apertures 31 to 34 is W, the length is L, and the depth is T. The value of W ranges from 0.05 times the 77GHz waveguide wavelength λg to 0.4 times the 77GHz waveguide wavelength λg, the value of L ranges from 0.25 times the 77GHz waveguide wavelength λg to 0.75 times the 77GHz waveguide wavelength λg, and the value of T is 1.2mm.

[0048] Preferably, the upper waveguide structure 1 and the lower waveguide structure 2 are manufactured using plastic metallization technology, with the interior being plastic and the outer surface being a copper-plated layer with a thickness of approximately 15 μm.

[0049] Preferably, the height of the first waveguide channel 6 is H1 and the width is A, and the value of H1 is 0.5mm.

[0050] Preferably, the height of the second waveguide channel 7 is H2, the width is A, and the value of H2 is B-H1.

[0051] Preferably, the first choke groove 51 and the second choke groove 52 are rounded rectangles with the same dimensions, a width of We, a length of Le, and a depth of H3. The value of We is 0.6 mm, and the value of H3 ranges from 0 to 0.5 times the 77 GHz waveguide wavelength λg.

[0052] Preferably, the first waveguide channel 6 and the second waveguide channel 7 are provided with chamfers at the bends, and the radius of the chamfer is in the range of 0 to 2A.

[0053] In summary, the bent cavity waveguide antenna structure proposed in this invention, suitable for millimeter-wave radar, achieves in-phase excitation of a row of collinearly arranged radiating apertures by bending the cavity, avoiding grating lobe splitting while expanding the E-plane beamwidth. It also boasts advantages such as small size and ease of fabrication. Figure 8 The simulation results of the return loss of the waveguide antenna structure are shown. The horizontal and vertical axes of the coordinate system represent frequency and return loss, respectively. That is, the bent cavity waveguide antenna of Example 1, suitable for millimeter-wave radar, can achieve a 10dB impedance bandwidth of 73.88GHz to 80.74GHz, thus covering the 76GHz to 79GHz required by vehicle-mounted millimeter-wave radar. For example... Figure 9 The simulation results of the radiation pattern of the bent cavity waveguide antenna suitable for millimeter-wave radar are shown. The horizontal and vertical axes in the coordinate system represent the beam angle and the achievable gain value, respectively. It can be seen that the bent cavity waveguide antenna suitable for millimeter-wave radar in Example 1 has a large E-plane beamwidth and an H-plane beam main-to-side lobe ratio of 22.5dB, which has excellent radiation characteristics.

[0054] This embodiment of the bent cavity waveguide antenna for millimeter-wave radar achieves a collinear arrangement of radiating apertures through a bent waveguide cavity design, allowing the apertures to be excited in phase for efficient electromagnetic wave radiation. The design, based on the center-to-center spacing of the radiating apertures corresponding to the half-waveguide wavelength, avoids oblique surface waves caused by grating lobe and sidelobe splitting, facilitating the expansion of the E-plane beamwidth. Furthermore, its compact size and ease of fabrication, eliminating the need for a power divider for feeding, enhance antenna layout flexibility and make mass production feasible. In addition, key parameters conform to the standard waveguide range, making this waveguide antenna suitable for various frequency bands.

Claims

1. A bent cavity waveguide antenna suitable for millimeter-wave radar, characterized in that, It includes several radial apertures arranged in a row, a first choke slot, a second choke slot, and a waveguide cavity; the projection shape of the waveguide cavity on the magnetic field plane includes a wavy, bent shape; the first choke slot and the second choke slot are respectively located on both sides of the several radial apertures; the radial apertures are connected to the waveguide cavity.

2. The bent cavity waveguide antenna suitable for millimeter-wave radar as described in claim 1, characterized in that, It includes an upper waveguide structure and a lower waveguide structure; the plurality of radiation holes, the first choke groove and the second choke groove are disposed on the upper waveguide structure; the upper waveguide structure is provided with a first waveguide channel, the lower waveguide structure is provided with a second waveguide channel, and the waveguide cavity is composed of the first waveguide channel and the second waveguide channel.

3. The bent cavity waveguide antenna suitable for millimeter-wave radar as described in claim 2, characterized in that, The wavy, zigzag shape includes rounded corners or sharp angles at the bends.

4. The bent cavity waveguide antenna suitable for millimeter-wave radar as described in claim 3, characterized in that, 0.04A≤D≤0.4A; where D is the distance between the geometric center of the radiation aperture and the central axis of the waveguide cavity, and A is the width of the waveguide cavity.

5. The bent cavity waveguide antenna suitable for millimeter-wave radar as described in claim 1, characterized in that, 0.05λg≤W≤0.4λg; where W is the width of the radiation aperture and λg is the waveguide wavelength corresponding to the bent cavity waveguide antenna suitable for millimeter-wave radar.

6. The bent cavity waveguide antenna suitable for millimeter-wave radar as described in claim 5, characterized in that, 0.25λg≤L≤0.75λg; where L is the length of the radiation aperture.

7. The bent cavity waveguide antenna suitable for millimeter-wave radar as described in claim 1, characterized in that, The shape of the radiation aperture includes at least one of rectangle, rounded rectangle, ellipse, and trapezoid.

8. The bent cavity waveguide antenna suitable for millimeter-wave radar as described in claim 1, characterized in that, The shapes of the first choke groove and the second choke groove include at least one of rectangle, rounded rectangle, ellipse, and trapezoid.

9. The bent cavity waveguide antenna suitable for millimeter-wave radar as described in claim 2, characterized in that, The materials used for the upper and lower waveguide structures include metallic materials.

10. The bent cavity waveguide antenna suitable for millimeter-wave radar as described in claim 9, characterized in that, The metal material is obtained by computer numerical control machining or by injection molding and plastic metallization process.

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