Waveguide antenna of millimeter wave radar

Abstract

The waveguide antenna comprises a first metal layer, a second metal layer and a third metal layer which are stacked in sequence, a plurality of radiation units are arranged on the surface of one side of the first metal layer, and a plurality of grooves corresponding to the radiation units are formed in the surface of the other side of the first metal layer. A plurality of rectangular grooves corresponding to the radiation units are formed in the surface of one side of the third metal layer, the first metal layer is provided with a plurality of first pins periodically surrounding the grooves, and gaps formed between the first pins and the first metal layer or the second metal layer are filled with first dielectric layers making contact with the first pins. According to the utility model, not only can the production process be simplified and the product yield be improved, but also the deviation of gaps between the plurality of pins and the corresponding metal layers can be bridged so as to maintain the consistency of the electromagnetic band gap characteristics of the periodic pins, thereby improving the consistency of the matching and gain of antennas in a large-scale mass production stage, and improving the production yield.

Description

Technical Field

[0001] The utility model relates to the technical field of millimeter wave radar, in particular to a waveguide antenna of a millimeter wave radar. Background Art

[0002] In recent years, due to the popularity of the concept of autonomous driving, its sensing technology has gradually come into the public eye. It can be mainly divided into three categories: cameras, lidar and millimeter-wave radar. Among them, millimeter-wave radar has a lower cost and all-weather detection capability. With the advancement of preparation technology and algorithms, the pitch and azimuth resolutions continue to improve, and it is increasingly favored by automobile manufacturers, with broad market prospects.

[0003] Early millimeter-wave radars were mainly implemented using microstrip array antennas or substrate-integrated waveguide (SIW) slot antennas. The above two types of antennas work on printed circuit boards and have large losses in the millimeter-wave frequency band, so their performance is poor. Subsequently, some manufacturers gradually adopted waveguide antennas as a product upgrade solution because of their low loss and high power capacity, which have unparalleled advantages in the 77GHz and even higher frequency bands. Although millimeter-wave radars based on waveguide antennas have excellent performance, with the wave of millimeter-wave radars about to be mass-produced, how to improve product yields, or how to reduce manufacturing processes and further reduce costs, still troubles the industry.

[0004] The existing 77GHz waveguide antenna is mainly prepared by injection molding and surface metallization process to make several layers of metal structure, and then use surface mount technology (SMT) to achieve sealing and electrical connection between each layer. In the above process, SMT is prone to tin leakage, tin overflow and other problems, and there are alignment errors, which affect the electrical dimensions of the waveguide cavity or feeder and increase the discontinuity in the signal transmission process. In the 77GHz frequency band with high manufacturing precision requirements, the above problems may cause the antenna's operating frequency to shift, impedance matching to deteriorate or energy leakage, and then affect key performance indicators such as gain, which cannot meet the needs of vehicle-mounted applications. Utility Model Content

[0005] The technical problem to be solved by the utility model is to provide a waveguide antenna for a millimeter-wave radar, which can not only simplify the production process and improve the product yield, but also bridge the deviation of the gap between each of a plurality of pins and the corresponding metal layer to maintain the consistency of the electromagnetic bandgap characteristics of the periodic pins, thereby improving the matching and gain consistency of the antenna in the large-scale mass production stage and improving the production yield.

[0006] In order to solve the above technical problems, the technical solution adopted by the utility model is: a waveguide antenna for a millimeter wave radar, comprising: a first metal layer, a second metal layer and a third metal layer stacked in sequence, a plurality of radiation units are arranged on the surface of the first metal layer opposite to the second metal layer, each of the radiation units includes a plurality of collinearly arranged radiation slots and choke slots respectively located on both sides of the radiation slot, a plurality of coupling through slots corresponding to the radiation units are opened on the second metal layer, a plurality of grooves corresponding to the radiation units are opened on the surface of the first metal layer facing the second metal layer, each of the radiation slots is connected to the corresponding groove, a plurality of rectangular grooves corresponding to the radiation units are opened on the surface of the third metal layer facing the second metal layer, and a vertical waveguide is embedded and installed at one end of each of the rectangular grooves;

[0007] A plurality of first pins periodically surrounding the grooves are arranged between the first metal layer and the second metal layer and on the outside of each groove, a first dielectric layer in contact with the first pins is filled in the gap formed between the first pins and the first metal layer or the second metal layer, a plurality of second pins periodically surrounding the rectangular grooves are arranged between the second metal layer and the third metal layer and on the outside of each rectangular groove, a second dielectric layer in contact with the second pins is filled in the gap formed between the second pins and the second metal layer or the third metal layer, the first metal layer, the first dielectric layer, the second dielectric layer and the third metal layer arranged in sequence are connected by a plurality of bolts, and a plurality of first through holes and second through holes corresponding to the coupling through grooves on the second metal layer are respectively opened on the first dielectric layer and the second dielectric layer.

[0008] The further improved scheme in the above technical scheme is as follows:

[0009] 1. In the above solution, the first pin is integrally formed on the surface of the first metal layer facing the second metal layer or on the surface of the second metal layer facing the first metal layer.

[0010] 2. In the above solution, the second pin is integrally formed on the surface of the third metal layer facing the second metal layer or on the surface of the second metal layer facing the third metal layer.

[0011] 3. In the above solution, the first metal layer, the second metal layer and the third metal layer are all metal plate layers or injection molded plate layers with metallized surfaces.

[0012] 4. In the above solution, a plurality of flange interfaces corresponding to the vertical waveguides are arranged on the surface of the third metal layer opposite to the second metal layer.

[0013] 5. In the above solution, the first dielectric layer and the second dielectric layer are both plastic film layers.

[0014] Due to the application of the above technical solution, the utility model has the following advantages compared with the prior art:

[0015] The utility model discloses a waveguide antenna for a millimeter-wave radar, wherein a plurality of grooves corresponding to the radiation units are provided on the surface of the first metal layer facing the second metal layer, each radiation groove is communicated with the corresponding groove, a plurality of rectangular grooves corresponding to the radiation units are provided on the surface of the third metal layer facing the second metal layer, a vertical waveguide is embedded and installed at one end of each rectangular groove, a plurality of first pins periodically surrounding the groove are provided between the first metal layer and the second metal layer and on the outside of each groove, a first dielectric layer in contact with the first pin is filled in the gap formed between the first pin and the first metal layer or the second metal layer, a plurality of second pins periodically surrounding the rectangular groove are provided between the second metal layer and the third metal layer and on the outside of each rectangular groove, the second pins and the second metal layer or the third metal layer are connected to each other. A second dielectric layer in contact with a second pin is filled in a gap formed between the metal layers; a first metal layer, a first dielectric layer, a second metal layer, a second dielectric layer and a third metal layer are sequentially connected by a plurality of bolts; a plurality of first through holes and a second through holes corresponding to the coupling through grooves on the second metal layer are respectively provided on the first dielectric layer and the second dielectric layer; a periodic pin structure is formed on both sides of the second metal layer by the first and second pins, and a dielectric layer is filled in a gap formed between each of the two periodic pin structures and the metal layer, which can simplify the production process and improve the product yield, and can also bridge the deviation of the gap between each of the multiple pins and the corresponding metal layer to maintain the consistency of the electromagnetic bandgap characteristics of the periodic pins, thereby improving the matching and gain consistency of the antenna in the large-scale mass production stage and improving the production yield. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Attached Figure 1 It is a front view structural diagram of the waveguide antenna of the millimeter wave radar of the utility model;

[0017] Attached Figure 2 It is a rear view structural schematic diagram of the waveguide antenna of the millimeter wave radar of the utility model;

[0018] Attached Figure 3 It is a schematic diagram of the structural disassembly of the waveguide antenna of the millimeter wave radar of the utility model;

[0019] Attached Figure 4 It is a schematic diagram of the assembly of the waveguide antenna of the millimeter wave radar of the utility model;

[0020] Attached Figure 5 The figure is a schematic diagram of the partial structure disassembly of the waveguide antenna of the millimeter wave radar of the utility model.

[0021] In the above figures: 1. first metal layer; 2. first dielectric layer; 21. first through hole; 3. second metal layer; 31. coupling through slot; 4. second dielectric layer; 41. second through hole; 5. third metal layer; 6. radiation unit; 61. radiation slot; 62. choke slot; 7. groove; 71. main body; 72. offset part; 81. first pin; 82. second pin; 9. rectangular slot; 10. vertical waveguide; 11. bolt; 12. flange interface. DETAILED DESCRIPTION

[0022] The present invention can be further understood through the specific embodiments given below, but they are not intended to limit the present invention.

[0023] Embodiment 1: A waveguide antenna for a millimeter wave radar, comprising: a first metal layer 1, a second metal layer 3 and a third metal layer 5 stacked in sequence, a plurality of radiation units 6 being arranged on the surface of the first metal layer 1 opposite to the second metal layer 3, each of the radiation units 6 comprising a plurality of collinearly arranged radiation slots 61 and choke slots 62 respectively located on both sides of the radiation slots 61, a plurality of coupling slots 31 corresponding to the radiation units 6 being provided on the second metal layer 3, a plurality of grooves 7 corresponding to the radiation units 6 being provided on the surface of the first metal layer 1 facing the second metal layer 3, each of the radiation slots 61 being connected to the corresponding groove 7, a plurality of rectangular grooves 9 corresponding to the radiation units 6 being provided on the surface of the third metal layer 5 facing the second metal layer 3, a vertical waveguide 10 being embedded and installed at one end of each of the rectangular grooves 9;

[0024] A plurality of first pins 81 periodically surrounding the groove 7 are provided between the first metal layer 1 and the second metal layer 3 and on the outside of each groove 7, a first dielectric layer 2 in contact with the first pin 81 is filled in the gap formed between the first pin 81 and the first metal layer 1 or the second metal layer 3, a plurality of second pins 82 periodically surrounding the rectangular groove 9 are provided between the second metal layer 3 and the third metal layer 5 and on the outside of each rectangular groove 9, a second dielectric layer 4 in contact with the second pin 82 is filled in the gap formed between the second pin 82 and the second metal layer 3 or the third metal layer 5, the first metal layer 1, the first dielectric layer 2, the second metal layer 3, the second dielectric layer 4 and the third metal layer 5 arranged in sequence are connected by a plurality of bolts 11, and a plurality of first through holes 21 and second through holes 41 corresponding to the coupling through grooves 31 on the second metal layer 3 are respectively provided on the first dielectric layer 2 and the second dielectric layer 4.

[0025] The first pins 81 are integrally formed on the surface of the first metal layer 1 facing the second metal layer 3 or on the surface of the second metal layer 3 facing the first metal layer 1 .

[0026] The second pins 82 are integrally formed on the surface of the third metal layer 5 facing the second metal layer 3 or on the surface of the second metal layer 3 facing the third metal layer 5 .

[0027] The first metal layer 1 , the second metal layer 3 and the third metal layer 5 are all metal plate layers.

[0028] A plurality of flange interfaces 12 correspondingly connected to the vertical waveguides 10 are arranged on the surface of the third metal layer 5 opposite to the second metal layer 3 .

[0029] The first dielectric layer 2 and the second dielectric layer 4 are both plastic film layers.

[0030] Embodiment 2: A waveguide antenna for a millimeter wave radar, comprising: a first metal layer 1, a second metal layer 3 and a third metal layer 5 stacked in sequence, a plurality of radiation units 6 being arranged on the surface of the first metal layer 1 opposite to the second metal layer 3, each of the radiation units 6 comprising a plurality of collinearly arranged radiation slots 61 and choke slots 62 respectively located on both sides of the radiation slots 61, a plurality of coupling slots 31 corresponding to the radiation units 6 being provided on the second metal layer 3, a plurality of grooves 7 corresponding to the radiation units 6 being provided on the surface of the first metal layer 1 facing the second metal layer 3, each of the radiation slots 61 being connected to the corresponding groove 7, a plurality of rectangular grooves 9 corresponding to the radiation units 6 being provided on the surface of the third metal layer 5 facing the second metal layer 3, a vertical waveguide 10 being embedded and installed at one end of each of the rectangular grooves 9;

[0031] A plurality of first pins 81 periodically surrounding the groove 7 are provided between the first metal layer 1 and the second metal layer 3 and on the outside of each groove 7, a first dielectric layer 2 in contact with the first pin 81 is filled in the gap formed between the first pin 81 and the first metal layer 1 or the second metal layer 3, a plurality of second pins 82 periodically surrounding the rectangular groove 9 are provided between the second metal layer 3 and the third metal layer 5 and on the outside of each rectangular groove 9, a second dielectric layer 4 in contact with the second pin 82 is filled in the gap formed between the second pin 82 and the second metal layer 3 or the third metal layer 5, the first metal layer 1, the first dielectric layer 2, the second metal layer 3, the second dielectric layer 4 and the third metal layer 5 arranged in sequence are connected by a plurality of bolts 11, and a plurality of first through holes 21 and second through holes 41 corresponding to the coupling through grooves 31 on the second metal layer 3 are respectively provided on the first dielectric layer 2 and the second dielectric layer 4.

[0032] The first pins 81 are integrally formed on the surface of the first metal layer 1 facing the second metal layer 3 or on the surface of the second metal layer 3 facing the first metal layer 1 .

[0033] The second pins 82 are integrally formed on the surface of the third metal layer 5 facing the second metal layer 3 or on the surface of the second metal layer 3 facing the third metal layer 5 .

[0034] The first metal layer 1 , the second metal layer 3 and the third metal layer 5 are all injection-molded plate layers with metallized surfaces.

[0035] The eight radiation units 6 are arranged in two rows and four columns, serving as transmitting antennas and receiving antennas respectively.

[0036] Each of the radiation units 6 has four rectangular radiation slots 61 arranged at equal intervals.

[0037] The groove 7 further includes a main body 71 extending along the arrangement direction of the radiation slots 61 in the corresponding radiation unit 6 and offset portions 72 respectively located at two ends of the main body 71 , and the two offset portions 72 are offset to the same side of the main body 71 .

[0038] The coupling through slot 31 , the first through hole 21 , and the second through hole 41 are all configured in a rectangular shape.

[0039] The further explanation of the above embodiment is as follows:

[0040] like Figure 1 , 2 As shown in Figure 3, the antenna consists of a total of 5 layers of structure, the first, third and fifth layers are metal parts, and the second and fourth layers are plastic films;

[0041] Eight groups of radiation units are provided on the upper surface of the first metal layer. Each group of radiation units includes four linearly arranged rectangular radiation slots and a pair of choke slots on both sides. The eight groups of radiation units are arranged in two rows and four columns, serving as transmitting antennas and receiving antennas (4T4R) respectively.

[0042] The lower surface of the first metal layer is provided with grooves corresponding to each radiation unit and a first pin periodic structure formed by a plurality of first pins surrounding the grooves. Specifically, Figure 4 As shown, one side of the groove is open, and the other side is connected to the rectangular radiation slot, and the two ends are partially offset compared to the center, and the first pin periodic structure includes a plurality of first pins, which periodically surround the open side of the groove;

[0043] The second metal layer is provided with rectangular coupling slots corresponding to each radiation unit;

[0044] like Figure 4 As shown, the upper surface of the third metal layer is provided with rectangular grooves corresponding to each radiation unit, a second pin periodic structure formed by a plurality of second pins surrounding the rectangular grooves, and a vertical waveguide, and the second pin periodic structure includes a plurality of second pins periodically surrounding the rectangular grooves;

[0045] The vertical waveguide is located at one end of the rectangular slot and extends to the lower surface of the third metal layer. According to the position of the vertical waveguide, a WR-12 standard flange interface is provided on the lower surface of the third metal layer;

[0046] The five-layer structure is provided with screw through holes for fixing, and the plastic film is provided with openings corresponding to the rectangular coupling grooves.

[0047] Based on this, the antenna can Figure 3 As shown, they are fixed to each other only by a few screws, which greatly simplifies the assembly process and does not require SMT soldering.

[0048] The five-layer structure is arranged from top to bottom in the order of a first metal layer, a first plastic film, a second metal layer, a second plastic film and a third metal layer;

[0049] After the assembly is completed, the first pin periodic structure is in contact with the upper surface of the first plastic film, and the lower surface of the second plastic film is in contact with the second pin periodic structure.

[0050] In the above assembly process, the first metal layer, the first pin periodic structure, the first plastic film and the second metal layer form a dielectric-filled gap waveguide cavity structure, and the second metal layer, the second plastic film, the second pin periodic structure and the third metal layer form a dielectric-filled slot gap waveguide transmission structure to reduce the loss during energy transmission.

[0051] When the signal is fed from the flange interface, it will be transmitted upward along the vertical waveguide in the TE10 mode to the dielectric-filled slot gap waveguide transmission structure. Under the action of the electromagnetic band gap of the first and second periodic pin structures, most of the signal is coupled upward to the dielectric-filled gap waveguide cavity structure through the rectangular coupling slot, and radiates energy outward through four rectangular radiation slots.

[0052] In addition, the choke slots on both sides of the radiation slot cause the laterally transmitted surface waves to produce secondary resonance, which can be superimposed on the main radiation beam at an appropriate spacing, having beneficial effects such as adjusting the beam width, increasing gain, and improving isolation, so that the antenna ultimately obtains good radiation performance.

[0053] It should be noted that the double-layer periodic pin structure of the present invention has no limitation on the length and width of the first and second pins. For example, the shape of the pins can be rectangular, cylindrical, triangular, or other shapes; there is no limitation on the arrangement and distribution of the pins, such as square, circular, or triangular distribution.

[0054] The dielectric filling in the present invention, i.e., the plastic film, only needs to ensure a high degree of processing precision to control the gap between the second metal layer and the first and second pin periodic structures, and epoxy resin, PET or PI can be selected. The pin shape, pin arrangement distribution method, and dielectric material do not affect the normal operation of the antenna.

[0055] In summary, the waveguide antenna of the millimeter-wave radar proposed in the present invention plays a positive role in improving product yield and reducing manufacturing costs, and is suitable for large-scale mass-produced vehicle-mounted millimeter-wave radars. On the one hand, a double-layer periodic pin structure symmetrically arranged above and below the second metal layer is used to replace part of the waveguide resonant cavity and the waveguide feeder, so that the first metal layer, the second metal layer and the third metal layer can work normally without perfect fit to form the waveguide cavity and the rectangular waveguide, thereby avoiding SMT welding in the assembly process of the traditional waveguide antenna, and the antenna performance will not be deteriorated due to SMT tin leakage, tin overflow, and alignment error; on the other hand, the gap waveguide is realized by dielectric filling rather than air gap. When problems such as warping and deformation occur during the actual processing process, the gap between the second metal layer and the first and second pin periodic structures can be strictly controlled to achieve insulation, which helps to maintain good electromagnetic bandgap characteristics and avoid large fluctuations in transmission loss.

[0056] Specifically, according to different frequency band requirements, the gap between the second metal layer and the first and second pin periodic structures is set to 0.05-1mm and filled with epoxy resin. The antenna achieves good matching and gain. The -15dB matching frequency band of the antenna is 75.24GHz~81.92GHz, which can cover the 76GHz~81GHz required by the vehicle-mounted millimeter-wave radar, and the maximum gain within the working frequency band can reach 14.7dBi.

[0057] When the waveguide antenna of the above-mentioned millimeter-wave radar is used, a periodic pin structure is formed on both sides of the second metal layer through the first and second pins, and a dielectric layer is filled in the gap formed between each of the two layers of periodic pin structures and the metal layer. This can not only simplify the production process and improve the product yield, but also bridge the deviation of the gap between each of the multiple pins and the corresponding metal layer to maintain the consistency of the electromagnetic bandgap characteristics of the periodic pins, thereby improving the matching and gain consistency of the antenna in the large-scale mass production stage and improving the production yield.

[0058] The above embodiments are only for illustrating the technical concept and features of the utility model, and their purpose is to enable people familiar with the technology to understand the content of the utility model and implement it accordingly, and they cannot be used to limit the protection scope of the utility model. Any equivalent changes or modifications made according to the spirit of the utility model should be included in the protection scope of the utility model.

Claims

1. A waveguide antenna for millimeter wave radar, characterized in that: include: A first metal layer (1), a second metal layer (3) and a third metal layer (5) are stacked in sequence, a plurality of radiation units (6) being arranged on a surface of the first metal layer (1) opposite to the second metal layer (3), each of the radiation units (6) comprising a plurality of radiation slots (61) arranged in a colinear manner and choke slots (62) respectively located on both sides of the radiation slots (61), a plurality of coupling slots (31) corresponding to the radiation units (6) being provided on the second metal layer (3), a plurality of grooves (7) corresponding to the radiation units (6) being provided on the surface of the first metal layer (1) facing the second metal layer (3), each of the radiation slots (61) being connected to a corresponding groove (7), a plurality of rectangular slots (9) corresponding to the radiation units (6) being provided on the surface of the third metal layer (5) facing the second metal layer (3), a vertical waveguide (10) being embedded and installed at one end of each of the rectangular slots (9); A plurality of first pins (81) are provided between the first metal layer (1) and the second metal layer (3) and are located on the outside of each groove (7), and the first pins (81) are periodically surrounding the groove (7); a first dielectric layer (2) in contact with the first pins (81) is filled in the gap formed between the first pins (81) and the first metal layer (1) or the second metal layer (3); a plurality of second pins (82) are provided between the second metal layer (3) and the third metal layer (5) and are located on the outside of each rectangular groove (9); the second pins A second dielectric layer (4) in contact with the second pin (82) is filled in the gap formed between the pin (82) and the second metal layer (3) or the third metal layer (5); the first metal layer (1), the first dielectric layer (2), the second metal layer (3), the second dielectric layer (4) and the third metal layer (5) arranged in sequence are connected by a plurality of bolts (11); and the first dielectric layer (2) and the second dielectric layer (4) are each provided with a plurality of first through holes (21) and second through holes (41) corresponding to the coupling through grooves (31) on the second metal layer (3).

2. The waveguide antenna for millimeter wave radar according to claim 1, characterized in that: The first pin (81) is integrally formed on a surface of the first metal layer (1) facing the second metal layer (3) or on a surface of the second metal layer (3) facing the first metal layer (1).

3. The waveguide antenna for millimeter wave radar according to claim 1, characterized in that: The second pin (82) is integrally formed on a surface of the third metal layer (5) facing the second metal layer (3) or on a surface of the second metal layer (3) facing the third metal layer (5).

4. The waveguide antenna for millimeter wave radar according to claim 1, characterized in that: The first metal layer (1), the second metal layer (3) and the third metal layer (5) are all metal plate layers or injection-molded plate layers with metallized surfaces.

5. The waveguide antenna for millimeter wave radar according to claim 1, characterized in that: A plurality of flange interfaces (12) correspondingly connected to the vertical waveguides (10) are arranged on a surface of the third metal layer (5) opposite to the second metal layer (3).

6. The waveguide antenna for millimeter wave radar according to claim 1, characterized in that: The first dielectric layer (2) and the second dielectric layer (4) are both plastic film layers.

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