Low-sidelobe waveguide slot antenna

Abstract

The invention discloses a low-sidelobe waveguide slot antenna, which belongs to the technical field of radars and comprises a waveguide body and a flexible printed board. The waveguide body comprises a U-shaped groove body and a cover body. The U-shaped groove body extends along a first direction, and one end of the U-shaped groove body is provided with a feed structure. The cover body extends in the first direction, and the cover body is detachably arranged at a notch of the U-shaped groove body, so that a rectangular cavity is formed between the U-shaped groove body and the cover body. The flexible printed board extends in the first direction, the two sides of the flexible printed board in the second direction are detachably fixed to the U-shaped groove body, and the flexible printed board covers the covering body. A metal layer is arranged on the outer wall face, away from the cover body, of the flexible printed board, and a plurality of gaps are formed in the metal layer at intervals in sequence in the first direction. The low-sidelobe waveguide slot antenna provided by the invention not only can ensure that the antenna has the characteristics of low sidelobe, high efficiency and good directionality, but also can reduce the machining precision requirement, and improves the antenna processing efficiency while ensuring the qualified rate of the antenna.

Description

Technical Field

[0001] This invention belongs to the field of radar technology, specifically relating to a low sidelobe waveguide slot antenna. Background Technology

[0002] A waveguide slot antenna is a linear array. A traveling wave array waveguide slot antenna connects a matched load to the waveguide termination, causing the waveguide to be in a traveling wave state, with the slots excited by the traveling wave. Traveling wave array waveguide slot antennas are widely used in ground-based radar due to their advantages of high power capacity, low loss, high aperture efficiency, low cost, and good directivity.

[0003] However, due to the requirements of ground radar for low sidelobes, high efficiency and good directivity of antennas, waveguide slot antennas usually have a large number of slots, and the depth and tilt angle of each slot are designed differently. Currently, conventional waveguide slot antennas use the method of directly opening slots in the metal wall of the waveguide cavity, which requires very high machining precision, is difficult to process, and usually results in a low antenna qualification rate. Summary of the Invention

[0004] In view of one or more of the above-mentioned defects or improvement needs of the prior art, the present invention provides a low sidelobe waveguide slot antenna, which not only ensures that the antenna has the characteristics of low sidelobe, high efficiency and good directivity, but also reduces the requirements for machining accuracy, thereby significantly improving the antenna processing efficiency while ensuring the antenna pass rate.

[0005] To achieve the above objectives, the present invention provides a low sidelobe waveguide slot antenna, comprising: A waveguide body, the waveguide body comprising a U-shaped groove and a cover; The U-shaped groove extends along the first direction, and one end of the U-shaped groove is provided with a power feeding structure for transmitting and receiving signals; The cover extends along a first direction and is detachably disposed at the opening of the U-shaped groove to form a rectangular cavity between the U-shaped groove and the cover; A flexible printed circuit board extends along a first direction, and both sides of the flexible printed circuit board in a second direction can be detachably fixed to the U-shaped groove. The flexible printed circuit board covers the cover. A metal layer is provided on the outer wall surface of the flexible printed circuit board away from the cover. A plurality of slits are provided on the metal layer at intervals along the first direction to obtain a sharp beam with good directionality, high gain, and low sidelobes.

[0006] As a further preferred embodiment of the present invention, the gap has vertical sections on both sides of the cover in the second direction and an inclined section disposed between the two vertical sections.

[0007] As a further preferred embodiment of the present invention, two adjacent gaps are symmetrically arranged along a first direction between them.

[0008] As a further preferred embodiment of the present invention, the angle between each of the inclined segments and the first direction satisfies a Taylor distribution.

[0009] As a further preferred embodiment of the present invention, the gap is formed by etching.

[0010] As a further preferred embodiment of the present invention, adhesive is provided on the end face of the flexible printed circuit board facing the cover.

[0011] As a further preferred embodiment of the present invention, the cover is made of a material with low dielectric constant, good wave transmission and high density.

[0012] As a further preferred embodiment of the present invention, the two outer sides of the opening end of the U-shaped groove are provided with corner grooves, and the end face of the cover facing the U-shaped groove is provided with two support plates spaced apart in a second direction. The two support plates are embedded in the corner grooves to block the opening of the U-shaped groove.

[0013] As a further preferred embodiment of the present invention, the flexible printed circuit board, the support plate, and the corner groove are provided with a plurality of connecting components arranged sequentially along a first direction for detachable connection between the flexible printed circuit board, the U-shaped groove, and the cover.

[0014] As a further preferred embodiment of the present invention, the connecting assembly includes screw holes coaxially formed on the flexible printed circuit board, the support plate and the corner slot, and bolts that pass through the screw holes in the flexible printed circuit board, the support plate and the corner slot in sequence, wherein the bolts are made of non-metallic material.

[0015] In summary, the beneficial effects of the above-described technical solutions conceived by this invention compared with the prior art include: (1) The low-sidelobe waveguide slot antenna of the present invention includes a waveguide body and a flexible printed circuit board. The waveguide body includes a U-shaped groove and a cover. The U-shaped groove extends along a first direction, and a feeding structure is provided at one end of the U-shaped groove for transmitting and receiving signals. The cover extends along the first direction, and the cover is detachably disposed at the groove opening of the U-shaped groove to form a rectangular cavity between the U-shaped groove and the cover. The flexible printed circuit board extends along the first direction, and both sides of the flexible printed circuit board in a second direction are detachably fixed to the U-shaped groove, and the flexible printed circuit board covers the cover. A metal layer is provided on the outer wall surface of the flexible printed circuit board away from the cover, and a plurality of slots are opened on the metal layer at intervals along the first direction for obtaining a sharp beam with good directivity, high gain, and low sidelobes. This low-sidelobe waveguide slot antenna not only ensures that the antenna has the characteristics of low sidelobes, high efficiency, and good directivity, but also reduces the requirements for machining accuracy, thereby significantly improving the antenna processing efficiency while ensuring the antenna pass rate.

[0016] (2) The low sidelobe waveguide slot antenna of the present invention uses rigid foam to prepare the cover structure, which enables the cover structure to have low dielectric constant, good wave transmission and high density, and is easy to process and form. At the same time, the processing technology of foldable flexible printed circuit board is mature, with high processing accuracy and good consistency, thereby reducing the processing difficulty while ensuring structural reliability.

[0017] (3) The low sidelobe waveguide slot antenna of the present invention uses a cover made of rigid foam material and a folded flexible printed circuit board as a sealed structure, which can avoid the hidden dangers of rainwater, dust and other corrosion at the slots of conventional waveguide slot antennas.

[0018] (4) The low-sidelobe waveguide slot antenna of the present invention is simple to manufacture, has a reliable structure, and is low in cost. It is formed by setting a cover at the opening end of the U-shaped slot and combining it with a flexible printed circuit board with a metal layer covering the outer wall of the cover, so that the flexible printed circuit board and the U-shaped slot can form a complete rectangular cavity. At the same time, by setting a number of slots evenly spaced along the first direction on the metal layer, and the tilt angle of each slot is Taylor distributed, a number of slot structures are formed on the rectangular waveguide resonant cavity, so that the resonant cavity can obtain a sharp beam with good directivity, high gain, and low sidelobes, thereby ensuring that the antenna has the characteristics of good directivity, high gain, and low sidelobes. Furthermore, by using the adhesive on the flexible printed circuit board facing the cover, the flexible printed circuit board can be directly disassembled and replaced when it is damaged or the antenna communication parameters need to be changed, thereby avoiding the risk of overall scrapping, and has good promotion value and application prospects. Attached Figure Description

[0019] Figure 1 This is a cross-sectional view of the overall structure of the low sidelobe waveguide slot antenna in this embodiment of the invention; Figure 2 This is an exploded view of the overall structure of the low sidelobe waveguide slot antenna in an embodiment of the present invention; Figure 3 This is a partially enlarged view of the unfolded state of the flexible printed circuit board of the low sidelobe waveguide slot antenna in an embodiment of the present invention. Figure 4 This is a 6.5GHz two-dimensional radiation pattern in a specific embodiment of the present invention; Figure 5 This is a 6.5GHz three-dimensional radiation pattern in a specific embodiment of the present invention.

[0020] In all the accompanying drawings, the same reference numerals denote the same technical features, specifically: 1. U-shaped groove; 2. Cover; 3. Flexible printed circuit board; 4. Gap; 5. Bolt; 6. Mounting plate; 7. Support plate; 8. Corner groove; 9. Vertical section; 10. Inclined section; 11. Fold line; 12. Screw hole. Detailed Implementation

[0021] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention. Furthermore, the technical features involved in the various embodiments of this invention described below can be combined with each other as long as they do not conflict with each other.

[0022] In the description of this invention, it should be understood that the terms "center," "first direction," "second direction," "length," "width," "thickness," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," "clockwise," "counterclockwise," "axial," "radial," and "circumferential" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing this invention and simplifying the description, and are not intended to 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 invention.

[0023] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one of that feature. In the description of this invention, "a plurality of" means at least two, such as two, three, etc., unless otherwise explicitly specified.

[0024] In this invention, unless otherwise explicitly specified and limited, the terms "installation," "connection," "linking," and "fixing," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components, unless otherwise explicitly limited. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0025] In this invention, unless otherwise explicitly specified and limited, "above" or "below" the second feature can mean that the first feature is in direct contact with the second feature, or that the first feature is in indirect contact with the second feature through an intermediate medium. Furthermore, "above," "over," and "on top" of the second feature can mean that the first feature is directly above or diagonally above the second feature, or simply that the first feature is at a higher horizontal level than the second feature. "Below," "below," and "under" the second feature can mean that the first feature is directly below or diagonally below the second feature, or simply that the first feature is at a lower horizontal level than the second feature.

[0026] Example: Please see Figures 1-5 The low sidelobe waveguide slot antenna in the preferred embodiment of the present invention not only ensures that the antenna has the characteristics of low sidelobe, high efficiency and good directivity, but also reduces the requirements for machining accuracy, thereby significantly improving the antenna processing efficiency while ensuring the antenna pass rate.

[0027] Specifically, such as Figures 1-3 As shown in the preferred embodiment of this application, the low sidelobe waveguide slot antenna includes a waveguide body and a flexible printed circuit board 3.

[0028] The waveguide body includes a U-shaped groove 1 and a cover plate. The U-shaped groove 1 extends along a first direction, and a feeding structure is provided at one end of the U-shaped groove 1 to facilitate signal transmission and reception. Simultaneously, the cover plate 2 extends along the first direction. Preferably, the length of the cover plate 2 in the first direction is the same as the length of the U-shaped groove 1 in the first direction. The cover plate 2 is detachably disposed at the opening of the U-shaped groove 1 to form a rectangular cavity between the U-shaped groove 1 and the cover plate 2, thereby forming a rectangular waveguide resonant cavity. Preferably, the U-shaped groove 1 is made of metal.

[0029] Furthermore, the flexible printed circuit board 3 extends along the first direction, and both sides of the flexible printed circuit board 3 in the second direction are detachably fixed to the U-shaped groove 1. Preferably, both sides of the flexible printed circuit board 3 in the second direction are detachably fixed to the two side walls of the opening of the U-shaped groove 1 in the second direction. At the same time, the flexible printed circuit board 3 covers the cover body 2, and a metal layer is provided on the outer wall surface of the flexible printed circuit board 3 facing away from the cover body 2. The metal layer on the flexible printed circuit board 3 is used to seal the opening of the U-shaped groove 1, thereby forming a complete rectangular waveguide resonant cavity. Furthermore, a plurality of slots 4 are formed on the metal layer at intervals along the first direction to form a plurality of slot 4 structures on the rectangular waveguide resonant cavity. This allows the resonant cavity to obtain a sharp beam with good directivity, high gain, and low sidelobes, thereby ensuring that the antenna has the characteristics of good directivity, high gain, and low sidelobes.

[0030] It is worth noting that in the preferred embodiment of this application, the extension direction of the waveguide body is the first direction, the width direction of the waveguide body is the second direction, and the height direction of the waveguide body is the third direction. The first direction is perpendicular to the second direction, and the third direction is perpendicular to both the first and second directions.

[0031] Furthermore, in a preferred embodiment of this application, the gap 4 has vertical segments 9 on both sides of the cover 2 in the second direction and an inclined segment 10 disposed between the two vertical segments 9. Preferably, two fold lines 11 extending in the first direction are provided on the flexible printed circuit board 3, and the two fold lines 11 are spaced apart in the second direction, so that the flexible printed circuit board 3 can be easily folded along the fold lines 11.

[0032] Preferably, the width between the two fold lines 11 on the flexible printed circuit board 3 is the same as the width of the cover plate, so as to ensure that the flexible printed circuit board 3 can cover the cover plate while also bending down to the two sides of the U-shaped groove 1 in the second direction, thereby forming a cover over the opening end of the U-shaped groove 1.

[0033] More preferably, the fold line 11 is the joint position between the vertical segment 9 and the inclined segment 10, so that the flexible printed circuit board 3 covers the cover plate, while the inclined segment 10 of the gap 4 falls on the top surface of the cover 2, and the two vertical segments 9 on both sides of the gap 4 can fall on the second direction side surfaces of the cover 2 after the fold line 11 is folded.

[0034] More preferably, in the preferred embodiment of this application, two adjacent gaps 4 are symmetrically arranged along a first direction between them. Specifically, the inclined segments 10 of two adjacent gaps 4 are complementary to the clamps in the first direction.

[0035] More specifically, in the preferred embodiment of this application, the angle between the inclined segment 10 in each slot 4 and the first direction satisfies a Taylor distribution, thereby maximizing antenna aperture efficiency while ensuring low sidelobe level, and keeping the main lobe beamwidth basically unchanged, that is, achieving a good balance between sidelobe level, beamwidth and aperture efficiency.

[0036] Furthermore, in a preferred embodiment of this application, each gap 4 is formed by etching, and each gap 4 penetrates the metal layer to adjust the structure of the resonant cavity. Simultaneously, since the gap 4 only penetrates the metal layer, and a flexible printed circuit board 3 is disposed below the metal layer, a cover 2 is also disposed at the opening end of the U-shaped groove 1 to seal the opening end of the U-shaped groove 1, thereby preventing the potential corrosion risks caused by contaminants such as rainwater and dust intruding into the interior of the U-shaped groove 1. Preferably, the metal layer is made of copper.

[0037] Further preferably, in the preferred embodiment of this application, adhesive is provided on the end face of the flexible printed circuit board 3 facing the cover 2, so that the flexible printed circuit board 3 can be accurately and conveniently bonded to the cover 2. If it is necessary to adjust the communication performance of the U-shaped groove 1, different flexible printed circuit boards 3 can be conveniently replaced by the adhesive structure between the flexible printed circuit board 3 and the cover 2. Its waveguide body can be reused, thereby avoiding the risk of overall scrapping in the event of test failure due to unqualified gap 4.

[0038] Furthermore, in a preferred embodiment of this application, the cover 2 is made of a material with low dielectric constant, good wave transmission, and high density, thereby ensuring good radiation performance while ensuring the strength of the antenna structure. Preferably, the cover is made of polymethacrylimide, which has a dielectric constant of less than 1.1 and a wave transmission rate of more than 99%.

[0039] Further preferably, in the preferred embodiment of this application, corner grooves 8 are provided on the two outer surfaces of the opening end of the U-shaped groove 1 in the second direction. Correspondingly, two support plates 7 are provided on the end face of the cover 2 facing the U-shaped groove 1, spaced apart along the second direction. The two support plates 7 are located on the bottom end face of the cover 2 near the two ends in the second direction. In actual use, the two support plates 7 of the cover 2 are embedded in the corner grooves 8 to seal the opening of the U-shaped groove 1, thereby facilitating the formation of a rectangular cavity.

[0040] More specifically, in a preferred embodiment of this application, the groove structure formed by the two support plates 7 and the cover 2 is fastened to the two corner grooves 8 of the U-shaped groove 1, that is, the two support plates 7 are respectively embedded in the two corner grooves 8 of the U-shaped groove 1, the two support plates 7 abut against the side wall surface of the corner groove 8, the ends of the two support plates 7 abut against the bottom end surface of the corner groove 8, and the cover 2 abuts against the groove opening end surface of the U-shaped groove 1. Preferably, the sum of the thickness of the support plate 7 and the thickness of the flexible printed circuit board 3 is equal to the second direction width of the corner groove 8. Preferably, the metal layer is in contact with the U-shaped groove 1, that is, the second direction side wall surface of the metal layer is in contact with the second direction side wall surfaces of the U-shaped groove 1.

[0041] Furthermore, in a preferred embodiment of this application, the flexible printed circuit board 3, the support plate 7, and the corner groove 8 are provided with a plurality of connecting components arranged sequentially along the first direction, for detachably fixing the flexible printed circuit board 3, the cover 2, and the U-shaped groove 1 into a whole.

[0042] Further preferably, in the preferred embodiment of this application, the connecting assembly includes screw holes 12 coaxially formed on the flexible printed circuit board 3, the support plate 7 and the corner groove 8, and bolts 5 passing through the screw holes 12 in sequence on the flexible printed circuit board 3, the support plate 7 and the corner groove 8, and the bolts 5 are made of non-metallic materials.

[0043] In actual use, bolt 5 is screwed into screw hole 12, thereby ensuring that flexible printed circuit board 3 and cover plate can be stably pressed into corner slot 8 of U-shaped groove 1.

[0044] Furthermore, in a preferred embodiment of this application, mounting plates 6 are provided at both ends of the U-shaped channel 1 in the first direction to facilitate stable installation of the U-shaped channel 1. Preferably, oblong holes are provided at the four corners of the mounting plates 6 to facilitate convenient connection of bolts 5. Preferably, a rectangular opening is provided on the mounting plate 6, which corresponds to the opening at the end of the U-shaped channel 1 in the first direction.

[0045] More preferably, in the preferred embodiment of this application, the U-shaped groove 1 is a rectangular parallelepiped structure, and the narrow side of the U-shaped groove 1, that is, the third-direction top surface, is provided with an opening of the U-shaped groove 1.

[0046] Furthermore, in a specific preferred embodiment of this application, the wall thickness of the U-shaped groove 1 is 2.5±0.01mm, and the thickness of the corresponding corner groove 8 of the U-shaped groove 1 is 1±0.01mm.

[0047] Furthermore, the cover 2 is made of polymethacrylimide material with a dielectric constant of less than 1.1 and a wave transmittance of more than 99%. The thickness of the support plate 7 is 1 ± 0.01 mm, and the thickness of the top structure of the cover 2 is 2 mm to 3 mm.

[0048] Furthermore, the flexible printed circuit board 3 has a thickness of 0.2mm to 0.5mm, and 64 slots 4 are provided on the flexible printed circuit board 3. The width of each slot 4 is 4.1871±0.01mm, the spacing between the slots 4 is 22±0.01mm, and the tilt angle of the 64 slots 4 is based on an average of 9.184°, distributed in a Taylor pattern, and symmetrical about the center. Except for the slots 4, the remaining surface of the flexible printed circuit board 3 is copper-clad to form a metal layer, and the copper-clad thickness is approximately 0.018mm. The flexible printed circuit board 3 has self-adhesive on the reverse side, and after being folded along the two fold lines 11, it is bonded to the cover 2 to form a U-shaped conformal structure.

[0049] Furthermore, after the folded flexible printed circuit board 3 is pasted onto the rigid foam cover 2, it is fixedly connected to the U-shaped groove 1 through a connecting component, in which the bolts 5 are made of non-metallic material.

[0050] More preferably, the waveguide slot antenna in this embodiment operates in the C-band with a bandwidth of not less than 500MHz, and simultaneously exhibits good two-dimensional and three-dimensional radiation patterns at 6.5GHz. Figure 4 and Figure 5 As shown, its azimuth sidelobe level is ≤ -32dB.

[0051] The low-sidelobe waveguide slot antenna of this invention is simple to manufacture, has a reliable structure, and is low in cost. It consists of a cover 2 at the opening of a U-shaped slot 1, and a flexible printed circuit board 3 with a metal layer covering the outer wall of the cover 2. This allows the flexible printed circuit board 3 and the U-shaped slot 1 to form a complete rectangular cavity. Simultaneously, several slots 4 are evenly spaced along a first direction on the metal layer, with each slot 4 having a Taylor distribution of tilt angles. This creates a slot structure 4 on the rectangular waveguide resonant cavity, enabling the resonant cavity to acquire a sharp beam with good directivity, high gain, and low sidelobes, thus ensuring the antenna possesses these characteristics. Furthermore, the adhesive on the flexible printed circuit board 3 facing the cover 2 allows for direct replacement of the flexible printed circuit board 3 in case of damage or changes to the antenna communication parameters, avoiding the risk of complete scrapping. This design has good promotional value and application prospects.

[0052] Those skilled in the art will readily understand that the above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A low sidelobe waveguide slot antenna, characterized in that, include: A waveguide body, the waveguide body comprising a U-shaped groove and a cover; The U-shaped groove extends along the first direction, and one end of the U-shaped groove is provided with a power feeding structure for transmitting and receiving signals; The cover extends along a first direction and is detachably disposed at the opening of the U-shaped groove to form a rectangular cavity between the U-shaped groove and the cover; A flexible printed circuit board extends along a first direction, and both sides of the flexible printed circuit board in a second direction can be detachably fixed to the U-shaped groove. The flexible printed circuit board covers the cover. A metal layer is provided on the outer wall surface of the flexible printed circuit board away from the cover. A plurality of slits are provided on the metal layer at intervals along the first direction to obtain a sharp beam with good directionality, high gain, and low sidelobes.

2. The low sidelobe waveguide slot antenna according to claim 1, characterized in that, The gap has vertical sections on both sides of the cover in the second direction and an inclined section disposed between the two vertical sections.

3. The low sidelobe waveguide slot antenna according to claim 2, characterized in that, The two adjacent gaps are symmetrically arranged along a first direction between them.

4. The low sidelobe waveguide slot antenna according to claim 3, characterized in that, The angle between each inclined segment and the first direction satisfies a Taylor distribution.

5. The low sidelobe waveguide slot antenna according to any one of claims 1 to 4, characterized in that, The gap was formed by etching.

6. The low sidelobe waveguide slot antenna according to any one of claims 1 to 4, characterized in that, The flexible printed circuit board has adhesive on its end face facing the cover.

7. The low sidelobe waveguide slot antenna according to any one of claims 1 to 4, characterized in that, The cover is made of a material with low dielectric constant, good wave transmission, and high density.

8. The low sidelobe waveguide slot antenna according to any one of claims 1 to 4, characterized in that, The two outer sides of the opening end of the U-shaped groove are provided with corner grooves, and the end face of the cover facing the U-shaped groove is provided with two support plates spaced apart in a second direction. The two support plates are embedded in the corner grooves to seal the opening of the U-shaped groove.

9. The low sidelobe waveguide slot antenna according to claim 8, characterized in that, The flexible printed circuit board, the support plate, and the corner groove are provided with a plurality of connecting components arranged sequentially along the first direction for detachable connection between the flexible printed circuit board, the U-shaped groove, and the cover.

10. The low sidelobe waveguide slot antenna according to claim 9, characterized in that, The connecting assembly includes screw holes coaxially formed on the flexible printed circuit board, the support plate, and the corner slot, and bolts that pass through the screw holes in the flexible printed circuit board, the support plate, and the corner slot in sequence, wherein the bolts are made of non-metallic material.

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