A waveguide antenna suitable for millimeter wave radar

Abstract

The embodiment of the application relates to the technical field of antennas, and provides a waveguide antenna suitable for a millimeter wave radar, which comprises a radiation layer, a resonance layer and a waveguide switching layer which are sequentially stacked; the radiation layer is provided with a plurality of radiation unit radiation layers; the resonance layer is provided with a first open cavity, a second open cavity and a coupling slot; and the waveguide switching layer is provided with a signal interface and a vertical waveguide. According to the technical scheme, a vertical coupling aperture is used to construct a longitudinally distributed waveguide feed line and a waveguide resonance cavity, so that the two form independent cavities with top or bottom openings based on the resonance layer, and therefore the antenna can be realized by only three layers of SMT packaging of metal plane structures, the production yield of the millimeter wave or terahertz band antenna can be greatly improved, the overall structure is simple, the preparation method is beneficial to improving the precision of key dimensions such as a radiation slot length and a spacing and reducing the deterioration influence of misplacement in a preparation process on the antenna performance, and production stability is high.

Description

Technical Field

[0001] This application relates to the field of antenna technology, and specifically to a waveguide antenna suitable for millimeter-wave radar. Background Technology

[0002] In recent years, with the increasing demand for Advanced Driving Assistance Systems (ADAS) and autonomous driving technology in the automotive market, millimeter-wave radar has attracted much attention due to its advantages such as all-weather operation, high precision, small size and low cost. It has a broad market and application scenarios, including but not limited to adaptive cruise control, collision avoidance systems, blind spot monitoring, lane departure warning and automatic emergency braking.

[0003] Multiple-input multiple-output (MIMO) antennas, as one of the core components of millimeter-wave radar, are currently mainly implemented through microstrip antennas, substrate integrated waveguide (SIW) slot antennas, and waveguide antennas. Among them, waveguide antennas operate based on rectangular waveguides, unlike microstrip antennas and SIW slot antennas which rely on printed circuit board (PCB) technology. In the 77GHz band and even higher frequency bands, waveguide antennas have much lower transmission losses than traditional waveguide antennas, and are therefore considered the future development trend of millimeter-wave radar antennas. Summary of the Invention

[0004] In order to achieve low-loss, high-precision and high-yield radar antennas in the 77GHz band or even higher, this application provides a waveguide antenna suitable for millimeter-wave radar.

[0005] This application provides a waveguide antenna suitable for millimeter-wave radar, comprising a radiating layer, a resonant layer, and a waveguide transition layer stacked sequentially.

[0006] The radiation layer is provided with multiple radiation unit radiation layers; a first open cavity is provided on one side surface of the resonant layer facing the radiation layer, which is directly opposite the radiation unit, and a second open cavity is provided on one side surface away from the radiation layer, so that a waveguide resonant cavity is formed by the first open cavity and one side surface of the radiation layer, and a horizontal waveguide feed line is formed by the second open cavity and one side surface of the waveguide transition layer. The resonant layer is also provided with a coupling groove connecting the first open cavity and the second open cavity.

[0007] A signal interface is provided on the side surface of the waveguide transition layer away from the resonant layer, and a vertical waveguide is provided to connect the second open cavity and the signal interface.

[0008] In one implementation, the radiating element includes a plurality of half-wavelength radiating slots and choke slots disposed on both sides of the half-wavelength radiating slots, and the choke slots extend from the radiating layer to the resonant layer.

[0009] In one implementation, the first open cavity includes a ridge structure and end structures disposed at both ends of the ridge structure;

[0010] The ridge structure is located near one side of the choke groove, and the end structure is located near the other side of the choke groove.

[0011] In one implementation, one end of the coupling groove is connected to the middle of the ridge structure, and the other end is connected to the end of the second open cavity.

[0012] In one implementation, the starting end of the second open cavity is provided with a transition slope that connects to the surface of the resonant layer.

[0013] In one implementation, the choke grooves disposed on the resonant layer are located on both sides of the first open cavity.

[0014] In one implementation, the number of the radiating elements, the first open cavity, the second open cavity, and the signal interface are all equal.

[0015] In one implementation, radiating units are formed on the radiating layer by etching copper foil.

[0016] In one implementation, a first open cavity and a second open cavity are formed by injection molding and copper plating on the resonant layer;

[0017] The signal interface and vertical waveguide are formed by injection molding and copper plating on the waveguide transition layer.

[0018] In one implementation, the distance between the half-wavelength radiation slot and the choke slot is 0.65λ0 to 0.55λ0.

[0019] This application provides a waveguide antenna suitable for millimeter-wave radar, comprising a radiating layer, a resonant layer, and a waveguide transition layer stacked sequentially. The radiating layer has multiple radiating elements. A first open cavity is disposed on one side of the resonant layer facing the radiating layer, directly opposite the radiating elements. A second open cavity is disposed on one side of the resonant layer away from the radiating layer, so as to form a waveguide resonant cavity through the first open cavity and one side of the radiating layer. A horizontal waveguide feed line is formed by the second open cavity and one side of the waveguide transition layer. The resonant layer also has a coupling groove connecting the first open cavity and the second open cavity. A signal interface is disposed on one side of the waveguide transition layer away from the resonant layer, and a vertical waveguide connecting the second open cavity and the signal interface is disposed thereon.

[0020] By applying this technical solution, a longitudinally distributed waveguide feed and waveguide resonant cavity are constructed using vertically coupled apertures, allowing them to form independent cavities with open tops or bottoms based on the resonant layer. Therefore, the antenna can be realized with only a three-layer metal planar structure SMT package. Furthermore, the top radiating unit is based on copper foil etching technology, which has high processing precision and can greatly improve the production yield of antennas in the millimeter-wave or terahertz bands. The overall structure is simple, and the proposed fabrication method is beneficial to improving the accuracy of key dimensions such as the length and spacing of the radiating slots and reducing the impact of misalignment during the fabrication process on the deterioration of antenna performance. It also has high production stability.

[0021] The above description is merely an overview of the technical solutions of the embodiments of the present invention. In order to better understand the technical means of the embodiments of the present invention and to implement them in accordance with the contents of the specification, and to make the above and other objects, features and advantages of the embodiments of the present invention more apparent and understandable, specific embodiments of the present invention are described below. Attached Figure Description

[0022] The accompanying drawings are for illustrative purposes only and are not intended to limit the invention. Furthermore, the same reference numerals denote the same parts throughout the drawings. In the drawings:

[0023] Figure 1 A schematic diagram of the overall structure of a waveguide antenna suitable for millimeter-wave radar provided in an embodiment of this application;

[0024] Figure 2 This is a schematic diagram of the surface structure of the radiation layer on both sides provided in an embodiment of this application;

[0025] Figure 3 This is a schematic diagram of the structure of the radiating unit provided in an embodiment of this application;

[0026] Figure 4 This is a schematic diagram of the surface structure of the resonant layer on both sides provided in an embodiment of this application;

[0027] Figure 5 This is a schematic diagram of the structure of the first open cavity provided in an embodiment of this application;

[0028] Figure 6 This is a schematic diagram of the structure of the second open cavity provided in an embodiment of this application;

[0029] Figure 7 This is a schematic diagram of the surface structure of both sides of the waveguide transition layer provided in an embodiment of this application;

[0030] Figure 8 This is a schematic diagram illustrating the relationship between the frequency and matching degree of the radiating element provided in an embodiment of this application;

[0031] Figure 9This is a schematic diagram showing the relationship between the frequency and gain of the radiating element provided in an embodiment of this application.

[0032] In the picture:

[0033] 1-Radiating layer, 11-Radiating unit, 111-Half-wavelength radiating slot, 112-Choke slot, 2-Resonant layer, 21-First open cavity, 211-Ridge structure, 212-End structure, 22-Second open cavity, 23-Coupled slot, 24-Transition slope, 3-Waveguide transition layer, 31-Signal interface, 32-Vertical waveguide. Detailed Implementation

[0034] Exemplary embodiments of the invention will now be described in more detail with reference to the accompanying drawings. While exemplary embodiments of the invention are shown in the drawings, it should be understood that the invention can be implemented in various forms and should not be limited to the embodiments set forth herein.

[0035] Multiple-input multiple-output (MIMO) antennas, as one of the core components of millimeter-wave radar, are currently mainly implemented through microstrip antennas, substrate integrated waveguide (SIW) slot antennas, and waveguide antennas. Among them, waveguide antennas operate based on rectangular waveguides, unlike microstrip antennas and SIW slot antennas which rely on printed circuit board (PCB) technology. At frequencies of 77 GHz and even higher, waveguide antennas have significantly lower transmission losses than microstrip antennas, and are therefore considered the future development trend of millimeter-wave radar antennas.

[0036] Current waveguide antennas suitable for millimeter-wave radar primarily utilize injection molding and surface metallization processes to fabricate multi-layered metal structures, typically four layers, which are then packaged using surface mount technology (SMT) to achieve the complete waveguide antenna structure. In this fabrication method, the waveguide feed line, waveguide cavity, and radiation slots are susceptible to two main factors:

[0037] 1. Manufacturing tolerances in injection molding: This is because the current application frequency band of millimeter-wave radar is mainly 76GHz~81GHz, and it is expected to be extended to the terahertz band in the future. The wavelength of the antenna is relatively short (λ=c / f, where c is the speed of light in vacuum and f is the center frequency of the antenna). Even small errors in the processing can cause the electrical dimensions of the antenna to deviate from the original design value.

[0038] 2. Alignment errors and solder leakage / overflow during the SMT process: These occur because during the SMT packaging of the antenna's various layers, slight misalignment between upper and lower layers, uneven solder paste distribution, insufficient mounting pressure, and improper temperature control can all lead to solder leakage / overflow. These issues alter the equivalent dimensions of the waveguide cavity and waveguide feed lines, increasing discontinuities in signal transmission. Both can cause performance degradation such as antenna frequency offset or mismatch.

[0039] Therefore, to reduce performance degradation, ensure the manufacturability and yield of millimeter-wave waveguide antennas, and control costs, the precision of the manufacturing process should be appropriately improved, and the number of SMT packaging layers should be reduced. One feasible design and fabrication method involves simplifying the antenna structure by designing the waveguide feed and waveguide cavity within the same plane. This allows for the creation of a complete waveguide antenna structure by SMT packaging only two metal half-cavity layers, thus reducing manufacturing costs. However, the dimensions of the radiating slot, waveguide cavity, and waveguide feed in this design are still limited by the precision of injection molding and SMT alignment, resulting in a lower yield.

[0040] In summary, this application provides a waveguide antenna suitable for millimeter-wave radar, which has excellent performance and simple structure, ensuring both low manufacturing cost and high manufacturing precision and yield, which is conducive to the large-scale mass production of antennas.

[0041] like Figure 1 As shown in the figure, a waveguide antenna suitable for millimeter-wave radar provided in this application embodiment includes a radiating layer 1, a resonant layer 2 and a waveguide transition layer 3 stacked sequentially.

[0042] Among them, such as Figure 2 As shown, the radiation layer 1 is provided with multiple radiation units 11. It should be noted that the radiation unit 11 has a groove-shaped structure and penetrates the structure of the radiation layer 1, such as... Figure 1 The structure is shown with two radiating units 11 labeled as the same on both sides of the radiating layer 1.

[0043] like Figure 4 As shown, a first open cavity 21 is provided on the side surface of the resonant layer 2 facing the radiation layer 1, which is directly opposite the radiation unit 11. A second open cavity 22 is provided on the side surface away from the radiation layer 1. In this way, a waveguide resonant cavity is formed by the first open cavity 21 and one side surface of the radiation layer 1, and a horizontal waveguide feed is formed by the second open cavity 22 and one side surface of the waveguide transition layer 3. A coupling groove 23 connecting the first open cavity 21 and the second open cavity 22 is also provided on the resonant layer 2.

[0044] like Figure 7As shown, a signal interface 31 is provided on the surface of the waveguide transition layer 3 away from the resonant layer 2, and a vertical waveguide 32 is provided to connect the second open cavity 22 and the signal interface 31.

[0045] In practical applications, the signal is fed in from signal interface 31, in the form of TE. 10 The mode is transmitted upward along the vertical waveguide 32, and after a slope transition, it enters the horizontal waveguide feed line (formed by the second open cavity 22 and one side surface of the waveguide transition layer 3). Then, it is coupled upward through the coupling groove 23 at the end of the horizontal waveguide feed line to the waveguide resonant cavity (formed by the first open cavity 21 and one side surface of the radiation layer 1), and then transmitted to the radiation unit 11.

[0046] In this embodiment, a waveguide antenna suitable for millimeter-wave radar is provided. The waveguide feed line is divided into two parts: a vertical waveguide 32 and a horizontal waveguide feed line. The horizontal waveguide feed line is generally arc-shaped and has a transition slope 24 that changes from vertical to horizontal direction. Specifically, as shown in the example... Figure 6 As shown, the starting end of the second open cavity 22 is provided with a transition slope 24 that connects to the surface of the resonant layer 2 to reduce TE. 10 This reduces discontinuities in the mode transmission process, thereby improving the overall impedance matching level of the antenna.

[0047] In some embodiments of this application, the radiation unit 11 includes a plurality of half-wavelength radiation slots 111 and choke slots 112 disposed on both sides of the half-wavelength radiation slots 111, for example, as Figure 3 As shown, the radiation unit 11 is provided with four half-wavelength radiation slots 111.

[0048] In some embodiments of this application, the shape of the first open cavity 21 is generally close to rectangular. Specifically, the two ends of the first open cavity 21 are partially offset relative to the middle, and a ridge is provided on one side of the middle of the first open cavity 21, such as... Figure 5 As shown, the first open cavity 21 includes a ridge structure 211 and end structures 212 disposed at both ends of the ridge structure 211; the ridge structure 211 is close to one side of the choke groove 112, and the end structures 212 are close to the other side of the choke groove 112. Among them, one end of the coupling groove 23 is connected to the middle of the ridge structure 211, and the other end is connected to the end of the second open cavity 22.

[0049] Using the waveguide antenna for millimeter-wave radar provided in this application, the signal is coupled upward to the middle of the waveguide resonant cavity through the coupling slot 23 at the end of the horizontal waveguide feed line, and transmitted to both ends of the waveguide resonant cavity under the action of the ridge structure 211, and radiated by four half-wavelength radiating slots 111. In addition, a pair of choke slots 112 on both sides of the half-wavelength radiating slots 111 can achieve surface wave suppression, which has beneficial effects such as improving gain, improving isolation, and suppressing sidelobes, so that the antenna can finally obtain high-gain stable radiation over a wide frequency band. The two ends of the first open cavity 21 are partially offset relative to the middle. The offset of the first open cavity 21 is equivalent to the offset of the radiating slots, so that the four half-wavelength radiating slots 111 distributed along the center line of the first open cavity 21 can obtain in-phase excitation, and the spacing between each half-wavelength radiating slot 111 and the choke slots 112 on both sides can be kept consistent. During this process, the waveguide resonant cavity and the half-wavelength radiation slot 111 obtain three controllable operating modes under the action of the transition slope 24 of the vertical-to-horizontal waveguide and the coupling slot 23, namely two cavity modes and one slot mode. The length and width of the waveguide resonant cavity and the length and spacing of the half-wavelength radiation slot 111 are the main control variables, respectively. Therefore, the important performance indicators such as impedance matching level, operating bandwidth and sidelobe level of the waveguide antenna suitable for millimeter-wave radar provided in this application embodiment are extremely sensitive to the above variables.

[0050] This application provides a waveguide antenna suitable for millimeter-wave radar. By minimizing the number of antenna layers, it reduces the impact of manufacturing errors on antenna performance, thus improving product yield. Firstly, the vertical coupling aperture achieves a longitudinal distribution of the horizontal waveguide feed line and the waveguide resonant cavity, meaning there is a height difference between them (in the stacking direction of radiating layer 1, resonant layer 2, and waveguide transition layer 3), avoiding mutual interference between the horizontal waveguide feed line and the waveguide resonant cavity in SMT alignment accuracy. Secondly, reasonable top-to-bottom layering allows the waveguide resonant cavity and horizontal waveguide feed line to be integrally formed with an open top or bottom, achieving a nearly complete cavity and further avoiding the impact of misalignment caused by SMT packaging on cavity dimensions. Furthermore, the array of half-wavelength radiating slots 111 on the top layer is achieved by etching copper foil, obtaining processing precision higher than injection molding. This helps reduce tolerances in key dimensions such as slot length and spacing, thereby providing a low-loss, high-precision, and high-yield radar antenna.

[0051] It should be noted that the distance between the half-wavelength radiation slot 111 and the choke slot 112 is 0.65λ0 to 0.55λ0, where λ0 is the wavelength of the radiation wave of the radiation element 11. It has the function of suppressing the surface wave transmission between each radiation element 11. By adjusting the depth of the choke slot 112 on the resonant layer 2, important performance indicators such as antenna isolation, gain and sidelobe level can be effectively improved.

[0052] In some embodiments of this application, the radiating layer 1, the resonant layer 2, and the waveguide transition layer 3 can be configured as a metal planar structure. For example, a radiating unit 11 is formed on the radiating layer 1 by etching copper foil, and a first open cavity 21 and a second open cavity 22 are formed on the resonant layer 2 by injection molding polyetherimide (PEI) and then plating copper.

[0053] It should be noted that in some embodiments of this application, the number of radiation units 11, first open cavity 21, second open cavity 22 and signal interface 31 are all equal. For example, the number of radiation units 11, first open cavity 21, second open cavity 22 and signal interface 31 is set to 8.

[0054] To more clearly illustrate the performance of a waveguide antenna suitable for millimeter-wave radar provided in the embodiments of this application, Figure 1 Taking the provided structure as an example, the matching and gain of a certain radiating element 11 are as follows: Figure 8 and Figure 9 As shown in the figure, the waveguide antenna provided in this application embodiment for millimeter-wave radar achieves good matching and gain over a wide frequency band. The -15dB matching frequency band of the waveguide antenna is 73.59GHz to 82.54GHz, which can cover the 76GHz to 81GHz required by millimeter-wave radar. Moreover, the gain flatness within the operating frequency band is good, and the maximum gain can reach 15.6dBi (antenna gain).

[0055] This application provides a waveguide antenna suitable for millimeter-wave radar. It utilizes vertically coupled apertures to construct longitudinally distributed waveguide feed lines and waveguide resonant cavities, allowing them to form independent cavities with open tops or bottoms based on the resonant layer 2. Therefore, the antenna can be realized with only a three-layer metal planar structure SMT package. Furthermore, the top radiating unit 11 is based on copper foil etching technology, which has high processing precision and can greatly improve the production yield of antennas in the millimeter-wave or terahertz frequency bands. The overall structure is simple, and the proposed fabrication method is beneficial to improving the accuracy of key dimensions such as the length and spacing of the radiating slots and reducing the impact of misalignment during the fabrication process on the deterioration of antenna performance. It also has high production stability.

[0056] The algorithms or displays provided herein are not inherently related to any particular computer, virtual system, or other device. Furthermore, the embodiments of this invention are not directed to any particular programming language.

[0057] Numerous specific details are set forth in the specification provided herein. However, it will be understood that embodiments of the invention may be practiced without these specific details. Similarly, for the sake of brevity and to aid in understanding one or more aspects of the invention, in the description of exemplary embodiments of the invention above, various features of the embodiments are sometimes grouped together in a single embodiment, figure, or description thereof. The claims, which follow the detailed description, are hereby expressly incorporated into that detailed description, wherein each claim itself is a separate embodiment of the invention.

[0058] Those skilled in the art will understand that the modules in the device of the embodiment can be adaptively changed and placed in one or more devices different from that embodiment. Modules, units, or components in the embodiment can be combined into a single module, unit, or component, and further, they can be divided into multiple sub-modules, sub-units, or sub-components, except that at least some of such features and / or processes or units are mutually exclusive.

[0059] It should be noted that the above embodiments are illustrative of the invention and not restrictive, and that those skilled in the art can devise alternative embodiments without departing from the scope of the appended claims. In the claims, any reference signs placed between parentheses should not be construed as limiting the claims. The word "comprising" does not exclude the presence of elements or steps not listed in the claims. The word "a" or "an" preceding an element does not exclude the presence of a plurality of such elements. The invention can be implemented by means of hardware comprising several different elements and by means of a suitably programmed computer. In the unit claims enumerating several means, several of these means may be embodied by the same item of hardware. The use of the words first, second, and third, etc., does not indicate any order. These words can be interpreted as names. The steps in the above embodiments, unless otherwise specified, should not be construed as limiting the order of execution.

Claims

1. A waveguide antenna suitable for millimeter-wave radar, characterized in that, It includes a radiation layer (1), a resonant layer (2), and a waveguide transition layer (3) stacked in sequence. The radiation layer (1) is provided with a plurality of radiation units (11); the resonant layer (2) has a first open cavity (21) facing the radiation unit (11) on one side surface facing the radiation layer (1), and a second open cavity (22) on the side surface away from the radiation layer (1), so as to form a waveguide resonant cavity through the first open cavity (21) and the side surface of the radiation layer (1) facing the resonant layer (2), and the second open cavity (22) and the side surface of the waveguide transition layer (3) facing the resonant layer (2) form a horizontal waveguide feed line. The resonant layer (2) is also provided with a coupling groove (23) connecting the first open cavity (21) and the second open cavity (22). Radiation units (11) are formed on the radiation layer (1) by etching copper foil. The radiation unit (11) includes a plurality of half-wavelength radiation slots (111) and choke slots (112) disposed on both sides of the half-wavelength radiation slots (111), and the choke slots (112) extend from the radiation layer (1) to the resonant layer (2). The first open cavity (21) includes a ridge structure (211) and end structures (212) disposed at both ends of the ridge structure (211). The ridge structure (211) is close to one side of the choke groove (112), and the end structure (212) is close to the other side of the choke groove (112). A signal interface (31) is provided on the side surface of the waveguide transition layer (3) away from the resonant layer (2), and a vertical waveguide (32) is provided to connect the second open cavity (22) and the signal interface (31). The starting end of the second open cavity (22) is provided with a transition slope (24) that connects to the surface of the resonant layer (2). The first open cavity (21) and the second open cavity (22) are formed by injection molding and copper plating on the resonant layer (2). The signal interface (31) and the vertical waveguide (32) are formed by injection molding and copper plating on the waveguide transition layer (3).

2. A waveguide antenna suitable for millimeter-wave radar according to claim 1, characterized in that, One end of the coupling groove (23) is connected to the middle part of the ridge structure (211), and the other end is connected to the end of the second open cavity (22).

3. A waveguide antenna suitable for millimeter-wave radar according to claim 1 or 2, characterized in that, The choke groove (112) disposed on the resonant layer (2) is located on both sides of the first open cavity (21).

4. A waveguide antenna suitable for millimeter-wave radar according to claim 1 or 2, characterized in that, The number of radiation units (11), first open cavity (21), second open cavity (22) and signal interface (31) are all equal.

5. A waveguide antenna suitable for millimeter-wave radar according to claim 1 or 2, characterized in that, The distance between the half-wavelength radiation slot (111) and the choke slot (112) is 0.

65. up to 0.55 , The wavelength of the radiation wave of the radiation unit (11).

Images