Multi-mode resonant waveguide slot antenna structure and waveguide radar

Abstract

The application provides a multi-mode resonant waveguide slot antenna structure and a waveguide radar, comprising: a waveguide antenna, the waveguide antenna has a waveguide channel; the waveguide channel comprises a waveguide input cavity, a waveguide power division cavity and a waveguide extension cavity, the waveguide input cavity is connected with the waveguide power division cavity vertically, and a T-shaped power division structure is formed; a plurality of waveguide extension cavities are connected with two ends of the waveguide power division cavity respectively and narrow openings are formed at the connecting positions; a plurality of radiation slots are arranged through the top of the waveguide channel. In the application, the connecting position of the waveguide power division cavity and the waveguide extension cavity forms a narrow opening, the width of the narrow opening is adjusted, multi-mode resonant modes are excited, and the bandwidth is expanded to a large extent; the width of the narrow opening can also adjust the energy distribution coupled into the extension cavity, so that the sidelobe level is very small. The waveguide antenna design provided by the application adopts a simplified T-shaped power division and waveguide cavity design, ensures the transmission performance and simplifies the structure design.

Description

Technical Field

[0001] This invention relates to the field of waveguide antenna technology, specifically to a multimode resonant waveguide slot antenna structure and a waveguide radar. Background Technology

[0002] Millimeter-wave radar is widely used in automotive radar, intelligent driving, smart transportation, ships, and aerospace.

[0003] Waveguide antennas offer excellent performance, but their high manufacturing precision requirements and cost have limited their widespread application in automotive radar. However, with advancements in materials science and processing technology in recent years, waveguide antennas have gradually gained greater attention and wider application in the automotive radar field.

[0004] With the development of intelligent driving, higher performance requirements have been put forward for millimeter-wave radar products, such as larger operating bandwidth (resolution), lower sidelobe level, and larger effective field of view.

[0005] Currently, waveguide antenna designs typically use resonant slot arrays as the main radiating element, employing metal or surface-metallized plastic as the base material. Due to the short wavelength of millimeter waves and the high precision requirements of manufacturing, bandwidth is extended by adding complex power divider structures or networks, but this also introduces problems such as complex manufacturing and high costs. Secondly, due to the size limitations of automotive radar antennas, it is impossible to further suppress sidelobe levels by increasing the number of radiating slots excessively; furthermore, an excessive number of radiating slots can lead to problems such as an insufficient elevation angle or excessive elevation direction deviation.

[0006] Therefore, a new waveguide antenna structure is needed to improve the above problems. Summary of the Invention

[0007] To address the shortcomings of existing technologies, the purpose of this invention is to provide a multimode resonant waveguide slot antenna structure and a waveguide radar.

[0008] According to the present invention, a multimode resonant waveguide slot antenna structure includes: a waveguide antenna having a waveguide channel;

[0009] The waveguide channel includes a waveguide input cavity, a waveguide power divider cavity, and a waveguide extension cavity. The waveguide input cavity and the waveguide power divider cavity are perpendicularly connected to each other to form a T-shaped power divider structure. The multiple waveguide extension cavities are respectively biased and connected to both ends of the waveguide power divider cavity, forming a narrow opening at the connection point.

[0010] The top of the waveguide channel has multiple radiating slots.

[0011] Preferably, the center plane of the H-plane of the waveguide input cavity is the first center plane;

[0012] One end of the waveguide input cavity is a waveguide feed port, and the other end of the waveguide input cavity is connected to the waveguide power splitter cavity, which is arranged symmetrically perpendicular to the first center plane.

[0013] Preferably, the center plane of the H-plane of the waveguide power divider cavity is the second center plane, and the center plane of the H-plane of the waveguide extension cavity is the third center plane. The second center plane and the third center plane are parallel and offset. The plurality of waveguide extension cavities are arranged perpendicularly and symmetrically about the second center plane.

[0014] Preferably, the connection between the waveguide power splitter cavity and each waveguide extension cavity forms two corners, the narrow opening is the area between the two corners, and the long side dimension of the narrow opening is smaller than the long side dimension of the waveguide power splitter cavity and the waveguide extension cavity.

[0015] Preferably, the third center plane is parallel to the second center plane and offset along the direction of the waveguide input cavity;

[0016] Each of the waveguide extension cavities forms a gap with the waveguide input cavity.

[0017] Preferably, the number of radial slits is even, and they are symmetrically distributed along the first central plane;

[0018] The first radiating slot, located on one side of the first center plane, is situated on the waveguide power divider cavity; the remaining radiating slots are situated on the waveguide extension cavity and are staggered along both sides of the third center plane.

[0019] Preferably, the central plane of the radial slit is a fourth central plane, and each of the fourth central planes is arranged parallel to the second or third central plane;

[0020] The offset of the fourth center plane from the second or third center plane decreases successively in the direction away from the first center plane.

[0021] Preferably, the waveguide channel adopts a closed waveguide cavity;

[0022] Alternatively, the waveguide channel is formed by an upper antenna layer, a lower antenna layer, and a magnetic conductor unit, wherein the magnetic conductor unit is located between the upper antenna layer and the lower antenna layer, and is either in contact with or not in contact with the upper antenna layer and the lower antenna layer, respectively.

[0023] According to the present invention, a waveguide radar includes the aforementioned multimode resonant waveguide slot antenna structure.

[0024] A vehicle according to the present invention includes the aforementioned waveguide radar.

[0025] Compared with the prior art, the present invention has the following beneficial effects:

[0026] 1. The waveguide antenna design proposed in this invention, by cascading multiple waveguide resonant cavities and forming a narrow-aperture structure at the connection between the waveguide resonant cavity and the waveguide extension cavity, excites dual-mode or multi-mode resonant modes, adds several beneficial zeros to the standing wave curve, and greatly expands the effective operating bandwidth.

[0027] 2. The waveguide antenna design proposed in this invention can effectively adjust the coupling strength between cavities by adjusting the position of the narrow aperture structure, thereby regulating the energy distribution of the radiation slot in the waveguide extension cavity and thus obtaining a more effective sidelobe level suppression effect.

[0028] 3. The waveguide antenna design proposed in this invention simplifies the design of the T-shaped power divider structure, eliminating the need for excessive power divider network structures or complex matching or allocation structures, and achieving the simplest structural design while ensuring transmission performance.

[0029] 4. In this invention, the waveguide extension cavity adopts an offset design, which allows multiple central radiating slots of the radiating slot array to be placed with a small offset or no offset, resulting in a more regular antenna radiation pattern, stronger directivity, and more stable far-field phase.

[0030] 5. The waveguide power divider cavity and narrow-aperture energy coupling design in this invention are different from the uniform cross-sectional size transmission of general waveguides, which can realize multimode resonance and effectively extend the ultra-wide operating bandwidth.

[0031] 6. The waveguide antenna design proposed in this invention achieves a larger operating bandwidth, more than twice the target operating bandwidth, thereby reducing the sensitivity to manufacturing errors in waveguide structure dimensions and making it more conducive to large-scale manufacturing.

[0032] 7. The waveguide antenna design proposed in this invention has excellent sidelobe suppression performance and better suppression effect on the deterioration of sidelobe level caused by large differences in operating wavelengths in in-band high-frequency or low-frequency operating modes.

[0033] 8. The waveguide structures such as the T-shaped power divider structure and the resonant cavity structure in this invention are all designed with a simple rectangular shape. The structure is simple and the size is moderate, which is conducive to optimizing the production process and reducing manufacturing costs.

[0034] 9. The waveguide antenna design proposed in this invention has a simple structure, minimizes the number of convergence parameters, which helps to improve the efficiency of design iteration and can quickly meet the technical requirements of different waveguide antenna application projects. Attached Figure Description

[0035] Other features, objects, and advantages of the present invention will become more apparent from the following detailed description of non-limiting embodiments with reference to the accompanying drawings:

[0036] Figure 1 This is a three-dimensional view of the waveguide channel in this invention.

[0037] Figure 2 This is a front view of the waveguide cavity in this invention;

[0038] Figure 3 This is a front view of the radial slit in this invention;

[0039] Figure 4 This is a front perspective view of the waveguide antenna (2 slots) in this invention;

[0040] Figure 5 This is a front perspective view of the waveguide antenna (4 slots) in this invention;

[0041] Figure 6 This is a front perspective view of the waveguide antenna (6 slots) in this invention;

[0042] Figure 7 This is a front perspective view of the waveguide antenna (8 slots) in this invention;

[0043] Figure 8 This is a three-dimensional view of the artificial magnetic conductor waveguide antenna in this invention;

[0044] Figure 9 This is a front view of the artificial magnetic conductor waveguide cavity and radiation slot in this invention;

[0045] Figure 10 This is a schematic diagram of the S-parameters of a waveguide antenna example in this invention. The S-parameters (Scatter parameters) are scattering parameters. In the figure, S(1,1) represents the input return loss.

[0046] Figure 11 The diagram shows the radiation pattern of an example waveguide antenna in the invention, where Azim is the azimuth angle and Elev is the elevation angle.

[0047] Explanation of reference numerals in the attached figures:

[0048] Detailed Implementation

[0049] The present invention will now be described in detail with reference to specific embodiments. These embodiments will help those skilled in the art to further understand the present invention, but do not limit the invention in any way. It should be noted that those skilled in the art can make several changes and improvements without departing from the concept of the present invention. These all fall within the protection scope of the present invention.

[0050] This invention provides a multimode resonant waveguide slot antenna structure with a simplified T-shaped power divider structure, significantly reducing manufacturing difficulty while ensuring transmission and radiation performance. By offsetting the waveguide power divider cavity and the waveguide extension cavity, multiple slots in the center of the slot array are arranged with small or no offset, solving the problems of poor antenna directivity and far-field phase instability. The staggered connection of the waveguide power divider cavity and the waveguide extension cavity forms a narrow aperture, allowing adjustment of the energy coupled into the waveguide extension cavity and achieving ultra-low sidelobe level control. The multimode resonance generated by the radiating slots and the narrow aperture achieves an ultra-wide operating bandwidth.

[0051] The structure of the waveguide antenna will be explained in further detail below.

[0052] Reference Figures 1 to 3 As shown, the multimode resonant waveguide slot antenna structure disclosed in this invention includes a waveguide antenna 1, which includes a waveguide channel 2. The waveguide channel 2 includes a waveguide input cavity 21, a waveguide power divider cavity 22, and a waveguide extension cavity 23, and a wave radiation slot 25 is vertically disposed through the waveguide channel 2.

[0053] The center plane of the H-plane of the waveguide input cavity 21 is the first center plane 211. Specifically, the first center plane 211 is perpendicular to the top surface of the H-plane of the waveguide input cavity (see reference). Figure 6 The center of the H-plane and the center of the bottom surface of the H-plane are shown, and the first center plane 211 extends along the direction of signal transmission in the waveguide input cavity.

[0054] One end of the waveguide input cavity 21 is open, serving as the waveguide feed port 212. Waveguide power divider cavities 22 are symmetrically arranged perpendicular to the first center plane 211, connecting with the waveguide input cavity 21 to form a T-shaped power divider structure. The T-shaped power divider structure has a simple outline and does not include traditional matching blocks, distribution blocks, or other special structures. This simplified T-shaped power divider structure optimizes the manufacturing process and significantly reduces manufacturing difficulty while meeting transmission and radiation performance requirements.

[0055] The center plane of the H-plane of the waveguide power divider cavity 22 is the second center plane 221, which is perpendicular to the first center plane 211. The specific position and structure of the second center plane 221 are similar to those of the first center plane 211, and will not be described in detail.

[0056] Two waveguide extension cavities 23 are respectively arranged in two directions along the second center plane 221 and connected to both ends of the waveguide power divider cavity 22. The center plane of the H-plane of the waveguide extension cavity 23 is the third center plane 231, which is parallel to the second center plane 221 and offset towards the waveguide input cavity 21 by a certain displacement. The two waveguide extension cavities 23 are perpendicular to and symmetrically arranged with respect to the second center plane 221. The specific position and structure of the third center plane 231 are similar to those of the first center plane 211 and will not be described in detail.

[0057] Two corners 241 are formed at the connection points between the waveguide power divider cavity 22 and each waveguide extension cavity 23. The two corners 241 form a narrow aperture 24, the long side of which is smaller than the long side of the waveguide power divider cavity 22 and the waveguide extension cavity 23. The interval between each waveguide extension cavity 23 and the waveguide input cavity 21 forms a gap 242. By introducing a narrow aperture structure into the original regular waveguide shape, multimode resonance can be excited during signal transmission, thereby forming several concave points on the signal standing wave curve and thus widening the bandwidth.

[0058] Specifically, the narrow-aperture 24 structure introduces higher-order modes to form a dual-mode or multi-mode coupling mechanism. The dual-mode or multi-mode coupling mechanism can realize energy exchange between modes and can introduce additional transmission zeros, thereby achieving a higher order in the same volume, which helps to expand bandwidth or improve frequency response characteristics.

[0059] Dual-mode or multi-mode coupling designs allow a single resonant cavity to function as multiple resonant elements. By cascading multiple dual-mode or multi-mode cavities, more zeros can be achieved without increasing physical dimensions, thereby widening the passband bandwidth. The coupling coefficient between modes directly affects the bandwidth. Enhancing coupling (e.g., increasing the coupling window size) expands the bandwidth, while weakening coupling narrows it. Therefore, a well-designed coupling structure can optimize bandwidth.

[0060] An even number of radiation slots 25 are disposed above the waveguide cavity, and the radiation slots 25 are symmetrically arranged along the first central plane 211; the central plane of each radiation slot 25 is a fourth central plane 251; specifically, the fourth central plane 251 is perpendicular to the center of the top end face and the center of the bottom end face of the radiation slot, and the fourth central plane 251 is parallel to the long side of the port of the radiation slot. Each fourth central plane 251 is arranged parallel to the second central plane 221 or the third central plane 231.

[0061] Starting from the first center plane 211, the first radiating slot 25 on one side is located within the projection area of ​​the waveguide power divider cavity 22 and is offset towards the waveguide input cavity 21 along one side of the second center plane 221. The second and all subsequent radiating slots 25 are arranged within the projection area of ​​the waveguide extension cavity 23. Along both sides of the third center plane 231, the fourth center plane 251 of the second radiating slot 25 is offset away from the waveguide input cavity 21, and the fourth center plane 251 of the third radiating slot 25 is offset towards the waveguide input cavity 21, and so on. The offset of the relevant center planes of the above radiating slots 25 decreases successively. The lateral spacing of all radiating slots 25 is close to or the same, approximately half the waveguide wavelength.

[0062] In one specific implementation, refer to Figure 3As shown, there are two radiation slots 25. At this time, the waveguide channel 2 only contains the waveguide input cavity 21 and the waveguide power splitter cavity 22; both radiation slots 25 are located in the projection area of ​​the waveguide power splitter cavity 22.

[0063] In one specific implementation, refer to Figures 5 to 7 As shown, the number of radiation slots 25 are four, six, and eight respectively; at this time, the waveguide channel 2 includes a waveguide input cavity 21, a waveguide power splitting cavity 22, and a waveguide extension cavity 23, wherein two radiation slots 25 are located in the projection area of ​​the waveguide power splitting cavity 22, and the remaining radiation slots are all located in the projection area of ​​the waveguide extension cavity.

[0064] On each side of the first center plane 211, adjust the offset between the third center plane 231 and the second center plane 221 so that the first radial slit 25 and the second radial slit 25 are arranged in a straight line or with a small offset.

[0065] Along the direction of signal transmission, the long side dimension of the cross-section of the waveguide power divider cavity 22 (i.e., the H-plane width of the waveguide power divider cavity 22) is close to or equal to the long side dimension of the cross-section of the waveguide extension cavity 23, and the short side dimension of the cross-section of the waveguide power divider cavity 22 (i.e., the E-plane height of the waveguide power divider cavity 22) is consistent with the short side dimension of the cross-section of the waveguide extension cavity. Both the long and short side dimensions meet the general requirements for the cutoff wavelength of the waveguide TE10 mode pair.

[0066] Along the direction of signal transmission, the long side dimension of the cross-section of the waveguide input cavity 21 (i.e., the H-plane width of the waveguide input cavity 21) is greater than the long side dimension of the cross-section of the waveguide power divider cavity 22, and the short side dimension of the cross-section of the waveguide input cavity 21 (i.e., the E-plane height of the waveguide input cavity 21) is the same as the short side dimension of the cross-section of the waveguide power divider cavity 22.

[0067] The length of the waveguide power divider cavity 22 is approximately one waveguide wavelength; the length of the waveguide extension cavity 23 is approximately equal to half the waveguide wavelength multiplied by the number of radiation slots 25 in the projected area. The width of the narrow aperture 24 is less than the width of the long side of the waveguide power divider cavity 22, and close to half the operating wavelength. The spacing 242 is appropriately wide to suit different processing methods.

[0068] In a preferred embodiment, refer to Figure 8 and Figure 9 As shown, artificial magnetic conductors can be used to replace closed waveguide cavities, which can provide some additional manufacturing cost optimization or manufacturing convenience while maintaining a similar level of antenna performance.

[0069] Specifically, in the practice of using artificial magnetic conductors, the waveguide antenna includes an upper antenna layer 26, a lower antenna layer 27, and a waveguide channel 2 formed by a certain number of magnetic conductor units 28. The structural features and dimensional relationships of the waveguide channel 2, including the waveguide input cavity 21, the waveguide power divider cavity 22, the waveguide extension cavity 23, and the radiation slot 25, are similar to those of the closed waveguide cavity structure.

[0070] In a preferred embodiment, the magnetic conductor unit 28 can also be replaced by one or more rings of enclosure structure, or by a combination of enclosure and magnetic conductor unit.

[0071] In a preferred embodiment, drawing upon the structural concept proposed in this invention, a 77GHz band six-radiating slot waveguide antenna for automotive radar was designed and developed, achieving a -10dB bandwidth of 11.6GHz, exceeding twice the target operating bandwidth (see reference). Figure 10 (as shown); and achieved radiation performance with a sidelobe level exceeding -30dB (see reference). Figure 11 (As shown).

[0072] In a preferred embodiment, the multimode resonant waveguide slot antenna structure provided by the present invention can be made of metal or surface-metallized non-metallic materials, and the processing technology can include manufacturing processes such as CNC machining, 3D printing, die casting, and injection molding. The fabrication process can involve integral fabrication, such as 3D printing; alternatively, it can be appropriately divided into double-layer or multi-layer structures, fabricated separately, and then assembled and connected using connection methods such as solder paste reflow soldering, ultrasonic welding, screwing, and adhesive bonding.

[0073] The present invention also discloses a waveguide radar that employs the aforementioned multimode resonant waveguide slot antenna structure. The present invention further discloses a vehicle that employs the aforementioned waveguide radar.

[0074] In the description of this application, it should be understood that the terms "upper", "lower", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this application.

[0075] Specific embodiments of the present invention have been described above. It should be understood that the present invention is not limited to the specific embodiments described above, and those skilled in the art can make various changes or modifications within the scope of the claims, which do not affect the essence of the present invention. Unless otherwise specified, the embodiments and features described in this application can be arbitrarily combined with each other.

Claims

1. A multimode resonant waveguide slot antenna structure, characterized in that, include: Waveguide antenna (1), the waveguide antenna (1) having a waveguide channel (2); The waveguide channel (2) includes a waveguide input cavity (21), a waveguide power divider cavity (22), and a waveguide extension cavity (23). The waveguide input cavity (21) is perpendicularly connected to the waveguide power divider cavity (22) to form a T-shaped power divider structure. The multiple waveguide extension cavities (23) are respectively biased and connected to both ends of the waveguide power divider cavity (22), and form a narrow opening (24) at the connection. The top of the waveguide channel (2) is provided with multiple radiation slots (25). The H-plane center plane of the waveguide input cavity (21) is the first center plane (211), and the waveguide power divider cavity (22) is arranged symmetrically perpendicular to the first center plane (211). The H-plane center plane of the waveguide power divider cavity (22) is the second center plane (221), and the H-plane center plane of the waveguide extension cavity (23) is the third center plane (231). The second center plane (221) and the third center plane (231) are parallel and offset. The multiple waveguide extension cavities (23) are arranged perpendicularly and symmetrically about the second center plane (221). The number of radial slits (25) is even and they are symmetrically distributed along the first central plane (211).

2. The multimode resonant waveguide slot antenna structure according to claim 1, characterized in that, One end of the waveguide input cavity (21) is a waveguide feed port (212), and the other end of the waveguide input cavity (21) is connected to the waveguide power divider cavity (22).

3. The multimode resonant waveguide slot antenna structure according to claim 1, characterized in that, The connection between the waveguide power divider cavity (22) and each waveguide extension cavity (23) forms a corner (241), and there are a total of two corners (241); the narrow opening (24) is the area between the two corners (241).

4. The multimode resonant waveguide slot antenna structure according to claim 1, characterized in that, The third center plane (231) is parallel to the second center plane (221) and offset along the direction of the waveguide input cavity (21); Each of the waveguide extension cavities (23) forms a gap (242) with the waveguide input cavity (21).

5. The multimode resonant waveguide slot antenna structure according to claim 1, characterized in that, The first radiation slot (25) located on one side of the first center plane (211) is located on the waveguide power divider cavity (22); the remaining radiation slots (25) are located on the waveguide extension cavity (23) and are staggered along both sides of the third center plane (231).

6. The multimode resonant waveguide slot antenna structure according to claim 5, characterized in that, The central plane of the radial slit (25) is a fourth central plane (251), and each of the fourth central planes (251) is arranged parallel to the second central plane (221) or the third central plane (231); The offset of the fourth center plane (251) from the second center plane (221) or the third center plane (231) decreases successively in the direction away from the first center plane (211).

7. A multimode resonant waveguide slot antenna structure, characterized in that, include: Waveguide antenna (1), the waveguide antenna (1) having a waveguide channel (2); The waveguide channel (2) is formed by an upper antenna layer (26), a lower antenna layer (27) and a magnetic conductor unit (28). The magnetic conductor unit (28) is located between the upper antenna layer (26) and the lower antenna layer (27), and is either in contact with or not in contact with the upper antenna layer (26) and the lower antenna layer (27), respectively. The waveguide channel (2) includes a waveguide input cavity (21), a waveguide power divider cavity (22), and a waveguide extension cavity (23). The waveguide input cavity (21) is perpendicularly connected to the waveguide power divider cavity (22) to form a T-shaped power divider structure. The multiple waveguide extension cavities (23) are respectively biased and connected to both ends of the waveguide power divider cavity (22), and form a narrow opening (24) at the connection. The top of the waveguide channel (2) is provided with multiple radiation slots (25). The H-plane center plane of the waveguide input cavity (21) is the first center plane (211), and the waveguide power divider cavity (22) is arranged symmetrically perpendicular to the first center plane (211). The H-plane center plane of the waveguide power divider cavity (22) is the second center plane (221), and the H-plane center plane of the waveguide extension cavity (23) is the third center plane (231). The second center plane (221) and the third center plane (231) are parallel and offset. The multiple waveguide extension cavities (23) are arranged perpendicularly and symmetrically about the second center plane (221). The number of radial slits (25) is even and they are symmetrically distributed along the first central plane (211).

8. A waveguide radar, characterized in that, The multimode resonant waveguide slot antenna structure includes any one of claims 1 to 7.

9. A car, characterized in that, Including the waveguide radar as described in claim 8.

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