Multi-mode resonant waveguide slot antenna structure and waveguide radar

Abstract

The invention provides a multimode resonant waveguide slot antenna structure and a waveguide radar, and the structure comprises a waveguide antenna which is provided with a waveguide channel; the waveguide channel comprises a waveguide input cavity, a waveguide power division cavity and a waveguide extension cavity, and the waveguide input cavity is vertically connected with the waveguide power division cavity to form a T-shaped power division structure; the plurality of waveguide extension cavities are in offset connection with the two ends of the waveguide power division cavity respectively, and narrow openings are formed at the joints; the top of the waveguide channel is provided with a plurality of radiation slots in a penetrating manner. The narrow opening is formed at the joint of the waveguide power division cavity and the waveguide extension cavity, a multimode resonant mode is excited by adjusting the width of the narrow opening, and the bandwidth is expanded to a large extent; the width of the narrow opening can also adjust energy distribution coupled into the extension cavity, so that ultra-small sidelobe level is achieved. According to the waveguide antenna design provided by the invention, the simplified T-shaped power divider and waveguide cavity design is adopted, the transmission performance is ensured, and the structural design is simplified to the greatest extent.

Description

Technical Field

[0001] The present invention relates to the technical field of waveguide antennas, and in particular to a multi-mode resonant waveguide slot antenna structure and a waveguide radar. Background Art

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

[0003] Waveguide antennas have excellent performance, but they cannot be widely used in the automotive radar field due to their high manufacturing precision requirements and high cost. In recent years, with the innovation of material science and processing technology, waveguide antennas have gradually received greater attention and application in the automotive radar field.

[0004] With the development of intelligent driving, higher performance requirements are placed on millimeter-wave radar products, such as larger operating bandwidth (resolution), lower sidelobe level, larger effective field of view, etc.

[0005] At present, the design of waveguide antenna products usually uses resonant slot arrays as the main radiation unit, and adopts metal materials or surface metallized plastic materials as the basic materials. Since the wavelength of millimeter waves is short and the processing accuracy requirements are relatively high, the bandwidth is extended by adding complex power division structures or power division networks, but this also brings problems such as complex processing and high costs. Secondly, due to the size limitations of automotive radar antennas, it is impossible to further suppress the sidelobe level by increasing the number of radiation slots; and too many radiation slots will lead to problems such as too small elevation viewing angle or too large deviation in the elevation direction.

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

[0007] In view of the defects in the prior art, an object of the present invention is to provide a multi-mode resonant waveguide slot antenna structure and a waveguide radar.

[0008] A multi-mode resonant waveguide slot antenna structure provided according to the present invention includes: a waveguide antenna, wherein the waveguide antenna has a waveguide channel;

[0009] The waveguide channel includes a waveguide input cavity, a waveguide power splitting cavity and a waveguide extension cavity. The waveguide input cavity is vertically connected to the waveguide power splitting cavity to form a T-shaped power splitting structure. The plurality of waveguide extension cavities are respectively connected to the two ends of the waveguide power splitting cavity in an offset manner and form a narrow opening at the connection.

[0010] A plurality of radiation slots are arranged through the top of the waveguide channel.

[0011] Preferably, the H-plane center 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 splitting cavity, and the waveguide power splitting cavity is symmetrically arranged perpendicular to the first center plane.

[0013] Preferably, the H-plane center plane of the waveguide power splitter cavity is the second center plane, the H-plane center plane of the waveguide extension cavity is the third center plane, the second center plane is parallel to the third center plane and is offset; the plurality of waveguide extension cavities are perpendicular and symmetrically arranged with respect to the second center plane.

[0014] Preferably, the connection between the waveguide power splitting 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 dimensions of the waveguide power splitting cavity and the waveguide extension cavity.

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

[0016] Each of the waveguide extension cavities is spaced apart from the waveguide input cavity.

[0017] Preferably, the radiation slots are set to an even number and are symmetrically distributed along the first center plane;

[0018] The first radiation slot located on one side of the first central plane is located on the waveguide power division cavity; the remaining radiation slots are located on the waveguide extension cavity and are staggered along both sides of the third central plane.

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

[0020] The offset of the fourth center plane parallel to the second center plane or the third center plane decreases gradually 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 surrounding an antenna upper layer, an antenna lower layer and a magnetic conductor unit, and the magnetic conductor unit is located between the antenna upper layer and the antenna lower layer, and is contact-connected or non-contact-connected to the antenna upper layer and the antenna lower layer respectively.

[0023] A waveguide radar provided according to the present invention comprises the multi-mode resonant waveguide slot antenna structure.

[0024] A car provided according to the present invention comprises the waveguide radar.

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

[0026] 1. The waveguide antenna design proposed in the present invention cascades multiple waveguide resonant cavities and forms a narrow structure at the connection between the waveguide resonant cavity and the waveguide extension cavity, thereby exciting a dual-mode or multi-mode resonant mode, adding a number of beneficial zero points on the standing wave curve, and greatly expanding the effective working bandwidth;

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

[0028] 3. The waveguide antenna design proposed in the present invention simplifies the design of the T-shaped power division structure, and does not need to set up too many power division network structures or complex matching or distribution structures. The structural design is simplified while ensuring the transmission performance.

[0029] 4. The waveguide extension cavity in the present invention adopts an offset design, so that the central multiple radiation slots of the radiation slot array can be placed with a small offset or no offset, the antenna radiation pattern is more regular, the directivity is stronger, and the radiation far-field phase is more stable.

[0030] 5. The waveguide power division cavity and the energy coupling design of the narrow mouth in the present invention are different from the uniform cross-sectional size transmission of general waveguides, and can realize multi-mode resonance and effectively expand the ultra-wide working bandwidth.

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

[0032] 7. The waveguide antenna design proposed in the present invention has excellent sidelobe suppression performance and has a better suppression effect on the deterioration of the sidelobe level caused by the large difference in working wavelength in the high-frequency or low-frequency working mode within the band.

[0033] 8. The designs of various waveguide structures such as the T-shaped power division structure and the resonant cavity structure in the present invention all adopt a simple rectangular design, which has a simple structure and a moderate size, and is conducive to optimizing the production process and reducing manufacturing costs.

[0034] 9. The waveguide antenna design proposed in the present invention has a simple structure and minimizes the number of convergence parameters, which is conducive to improving the efficiency of design iterations and can quickly meet the technical requirements of different waveguide antenna application projects. BRIEF DESCRIPTION OF THE DRAWINGS

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

[0036] Figure 1 It is a front stereoscopic view of the waveguide channel in the present invention;

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

[0038] Figure 3 It is a front view of the radiation gap in the present invention;

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

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

[0041] Figure 6 It is a front perspective view of the waveguide antenna (6 slots) of the present invention;

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

[0043] Figure 8 A three-dimensional diagram of the artificial magnetic conductor waveguide antenna of the present invention;

[0044] Fig. 9 It is a front view of the artificial magnetic conductor waveguide cavity and the radiation gap in the present invention;

[0045] Fig.10 Schematic diagram of S parameters of the waveguide antenna example in the present invention, S parameters (Scatter parameters), that is, scattering parameters, in which S (1,1) represents input return loss;

[0046] Fig.11 This is the radiation diagram of the waveguide antenna example in the invention, where Azim is the azimuth angle and Elev is the elevation angle.

[0047] Description of reference numerals:

[0048] DETAILED DESCRIPTION

[0049] The present invention is described in detail below in conjunction with specific embodiments. The following embodiments will help those skilled in the art to further understand the present invention, but are not intended to limit the present invention in any form. It should be noted that, for those of ordinary skill in the art, several changes and improvements can also be made without departing from the concept of the present invention. These all belong to the protection scope of the present invention.

[0050] The present invention provides a multi-mode resonant waveguide slot antenna structure, which has a simplified T-type power splitter structure, and significantly reduces the difficulty of manufacturing while ensuring transmission and radiation performance. By biasing the connection between the waveguide power splitter cavity and the waveguide extension cavity, a small bias amount or no bias arrangement of multiple slots in the center of the slot array is formed, which solves the problems of poor antenna directivity and far-field phase instability. By staggering the connection between the waveguide power splitter cavity and the waveguide extension cavity to form a narrow mouth, the amount of energy coupled into the waveguide extension cavity can be adjusted to achieve ultra-low sidelobe level control. The multi-mode resonance formed by the excitation of the radiation slot and the narrow mouth achieves an ultra-wide working bandwidth.

[0051] The structure of the waveguide antenna is described in further detail below.

[0052] Reference Figures 1 to 3 As shown, the multi-mode resonant waveguide slot antenna structure disclosed in the present invention includes a waveguide antenna 1, and the waveguide antenna 1 includes a waveguide channel 2. The waveguide channel 2 includes a waveguide input cavity 21, a waveguide power division cavity 22 and a waveguide extension cavity 23, and a wave radiation slot 25 is vertically arranged on 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 (refer to Figure 6 The first center plane 211 is arranged to extend along the direction in which the signal is transmitted in the waveguide input cavity.

[0054] One end of the waveguide input cavity 21 is open, which is the waveguide feed port 212. The waveguide power splitter cavity 22 is symmetrically arranged perpendicular to the first center plane 211, and is connected to the waveguide input cavity 21 to form a T-shaped power splitter structure. The T-shaped power splitter structure has a simple outline and does not include special structures such as traditional matching blocks and distribution blocks. Through the simplified T-shaped power splitter structure, the manufacturing process is optimized while meeting the transmission and radiation performance, and the manufacturing difficulty is significantly reduced.

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

[0056] Two waveguide extension cavities 23 are respectively arranged along the two directions of the second center plane 221, and are connected to the two ends of the waveguide power splitter cavity 22; the H-plane center plane of the waveguide extension cavity 23 is the third center plane 231, and the third center plane 231 is parallel to the second center plane 221 and deviates a certain displacement in the direction of the waveguide input cavity 21. The two waveguide extension cavities 23 are perpendicular to the second center plane 221 and are symmetrically arranged. The specific position structure of the third center plane 231 is similar to that of the first center plane 211, and will not be described in detail.

[0057] Two corners 241 are formed at the connection between the waveguide power splitting cavity 22 and each waveguide extension cavity 23, and the two corners 241 form a narrow opening 24, and the long side dimension of the narrow opening 24 is smaller than the long side dimension of the waveguide power splitting cavity 22 and the waveguide extension cavity 23. The interval between each waveguide extension cavity 23 and the waveguide input cavity 21 forms an interval 242. The narrow opening structure is introduced into the original regular waveguide shape, which can excite multi-mode resonance during the transmission of the signal, thereby forming a number of concave points on the signal standing wave curve, thereby widening the bandwidth.

[0058] Specifically, the narrow mouth 24 structure introduces a high-order mode 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 the bandwidth or improve the frequency response characteristics.

[0059] The dual-mode or multi-mode coupling design makes a single resonant cavity equivalent to multiple resonant units. By cascading multiple dual-mode or multi-mode cavities, more zero points can be achieved without increasing the physical size, thereby widening the passband bandwidth. The coupling coefficient between modes directly affects the bandwidth. Increasing the coupling (such as increasing the coupling window size) can expand the bandwidth, while weakening the coupling narrows the bandwidth. Therefore, a reasonable design of the coupling structure can achieve bandwidth optimization.

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

[0061] Starting from the first center plane 211, the first radiation slot 25 on one side is set in the projection area of ​​the waveguide power splitter cavity 22, and is offset along the side of the second center plane 221 in the direction close to the waveguide input cavity 21; the second and all subsequent radiation slots 25 are arranged in 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 radiation slot 25 is offset in the direction away from the waveguide input cavity 21, and the fourth center plane 251 of the third radiation slot 25 is offset in the direction close to the waveguide input cavity 21, and so on; the offset amounts of the central planes related to the above radiation slots 25 decrease successively; the lateral spacings of all radiation slots 25 are close or the same, approximately 1 / 2 of the waveguide wavelength.

[0062] In a specific embodiment, referring to Figure 3As shown, the number of the radiation slots 25 is two. At this time, the waveguide channel 2 only includes the waveguide input cavity 21 and the waveguide power splitting cavity 22 ; the two radiation slots 25 are both located in the projection area of ​​the waveguide power splitting cavity 22 .

[0063] In a specific embodiment, referring to Figures 5 to 7 As shown, the number of radiation slots 25 is 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 central plane 211 , the offset between the third central plane 231 and the second central plane 221 is adjusted so that the first radiation slot 25 and the second radiation slot 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 splitter cavity 22 (i.e., the H-plane width of the waveguide power splitter 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 splitter cavity 22 (i.e., the E-plane height of the waveguide power splitter cavity 22) is consistent with the short side dimension of the cross section of the waveguide extension cavity, and both the long side and short side dimensions meet the general requirements of the waveguide TE10 mode for the cut-off wavelength.

[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 larger than the long side dimension of the cross section of the waveguide power splitter 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 consistent with the short side dimension of the cross section of the waveguide power splitter cavity 22.

[0067] The length of the waveguide power splitting cavity 22 is approximately one waveguide wavelength; the length of the waveguide extension cavity 23 is approximately equal to 1 / 2 of the waveguide wavelength multiplied by the number of radiation slots 25 in the projection area. The width of the narrow opening 24 is smaller than the long side width of the waveguide power splitting cavity 22, and is close to 1 / 2 of the working wavelength. The interval 242 has an appropriate width to suit different processing methods.

[0068] In a preferred embodiment, referring to Figure 8 and Fig. 9 As shown, an artificial magnetic conductor can be used to replace the closed waveguide cavity, which can achieve some additional manufacturing cost optimization or manufacturing convenience while maintaining a similar level of antenna performance.

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

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

[0071] In a preferred embodiment, the structural idea proposed in the present invention is used to design and develop a 77GHz band 6-radiation slot waveguide antenna for automotive radar, which can achieve a -10dB bandwidth of 11.6G, more than twice the target working bandwidth (refer to Fig.10 and achieved a radiation performance of more than -30dB sidelobe level (refer to Fig.11 shown).

[0072] In a preferred embodiment, the multi-mode resonant waveguide slot antenna structure provided by the present invention can be made of metal or non-metallic material with metallized surface, and the processing technology can be such as CNC machining, 3D printing, die casting, injection molding and other manufacturing processes. It can be made as a whole, such as 3D printing, etc.; it can also be appropriately divided into double-layer or multi-layer structures, and assembled and connected by connection methods such as solder paste reflow soldering, ultrasonic welding, screw connection, gluing, etc. after being made separately.

[0073] The invention also discloses a waveguide radar, which adopts the multi-mode resonant waveguide slot antenna structure. The invention also discloses a car, which adopts the waveguide radar.

[0074] In the description of the present application, it should be understood that the terms "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", etc., indicating orientations or positional relationships, are based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present application and simplifying the description, and do not indicate or imply that the referred device or element must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as a limitation on the present application.

[0075] The above describes the specific embodiments of the present invention. It should be understood that the present invention is not limited to the above specific embodiments, and those skilled in the art can make various changes or modifications within the scope of the claims, which does not affect the essence of the present invention. In the absence of conflict, the embodiments of the present application and the features in the embodiments can be combined with each other arbitrarily.

Claims

1. A multimode resonant waveguide slot antenna structure, characterized in that: include: A waveguide antenna (1), wherein the waveguide antenna (1) has a waveguide channel (2); The waveguide channel (2) comprises a waveguide input cavity (21), a waveguide power splitting cavity (22) and a waveguide extension cavity (23); the waveguide input cavity (21) is vertically connected to the waveguide power splitting cavity (22) to form a T-shaped power splitting structure; a plurality of waveguide extension cavities (23) are respectively connected to two ends of the waveguide power splitting cavity (22) in an offset manner, and a narrow opening (24) is formed at the connection; A plurality of radiation slots (25) are arranged through the top of the waveguide channel (2).

2. The multimode resonant waveguide slot antenna structure according to claim 1, characterized in that: The H-plane center plane of the waveguide input cavity (21) is a first center plane (211); One end of the waveguide input cavity (21) is a waveguide feed port (212), the other end of the waveguide input cavity (21) is connected to the waveguide power splitting cavity (22), and the waveguide power splitting cavity (22) is symmetrically arranged perpendicular to the first center plane (211).

3. The multimode resonant waveguide slot antenna structure according to claim 1, characterized in that: The H-plane center plane of the waveguide power splitting cavity (22) is a second center plane (221), the H-plane center plane of the waveguide extension cavity (23) is a third center plane (231), the second center plane (221) is parallel to the third center plane (231) and is offset; the plurality of waveguide extension cavities (23) are vertically and symmetrically arranged with respect to the second center plane (221).

4. The multimode resonant waveguide slot antenna structure according to claim 3, characterized in that: Two corners (241) are formed at the connection between the waveguide power splitting cavity (22) and each waveguide extension cavity (23), and the narrow opening (24) is the area between the two corners (241).

5. The multi-mode resonant waveguide slot antenna structure according to claim 3, characterized in that: The third center plane (231) is parallel to the second center plane (221) and is 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).

6. The multi-mode resonant waveguide slot antenna structure according to claim 3, characterized in that: The radiation slots (25) are set to be an even number and are symmetrically distributed along the first center plane (211); The first radiation slot (25) located on one side of the first central plane (211) is located on the waveguide power division cavity (22); the remaining radiation slots (25) are located on the waveguide extension cavity (23) and are staggered along both sides of the third central plane (231).

7. The multi-mode resonant waveguide slot antenna structure according to claim 6, characterized in that: The central plane of the radiation slot (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) parallel to the second center plane (221) or the third center plane (231) decreases gradually in a direction away from the first center plane (211).

8. The multi-mode resonant waveguide slot antenna structure according to claim 1, characterized in that: The waveguide channel (2) adopts a closed waveguide cavity; Alternatively, the waveguide channel (2) is formed by surrounding an antenna upper layer (26), an antenna lower layer (27) and a magnetic conductor unit (28), wherein the magnetic conductor unit (28) is located between the antenna upper layer (26) and the antenna lower layer (27), and is contact-connected or non-contact-connected to the antenna upper layer (26) and the antenna lower layer (27), respectively.

9. A waveguide radar, characterized in that: The invention comprises the multi-mode resonant waveguide slot antenna structure according to any one of claims 1 to 8.

10. An automobile, characterized in that: Includes the waveguide radar as described in claim 9.

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