Radiation back cavity unit of gap waveguide back cavity slot array antenna and array antenna

Abstract

The utility model discloses a radiation back cavity unit of a gap waveguide back cavity slot array antenna and an array antenna. The radiation back cavity unit comprises an upper layer metal plate, a plurality of radiation slots, an opening cavity, a lower layer metal plate, more than one coupling slot and a plurality of metal columns. A through hole is formed in the lower metal plate to form a coupling gap, and a plurality of metal stand columns are arranged on the peripheral side of the coupling gap in a surrounding mode; the plurality of radiation slots are positioned on the upper-layer metal plate and are positioned on the two sides of the coupling slot; the opening cavities are located on the upper metal plate and located on the two sides of the coupling gap. And the radiation slots on the same side of the coupling slot are positioned in the same open cavity. The antenna has the advantages of simple structure, high antenna gain and efficiency and the like.

Description

Technical Field

[0001] The utility model mainly relates to the technical field of slot waveguide antennas, and particularly relates to a radiation back cavity unit and an array antenna of a slot waveguide back cavity slot array antenna. Background Technique

[0002] As the front end of a radar system, the performance of an antenna determines the pros and cons of the detection performance of the radar system. For a radar antenna, antenna efficiency is one of the key research issues. A high-efficiency terminal antenna can improve the power utilization rate of the system, achieve higher gain, and thus increase the accuracy of radar detection and the detection range. In the millimeter-wave band, antennas based on microstrip and substrate integrated waveguide structures have reduced antenna efficiency due to large dielectric plate losses; for waveguide slot antennas, although their losses are small, due to the high requirements for electrical contact at the joints during segmented processing and assembly, even a slight gap can cause significant energy leakage, thereby reducing the antenna performance. To improve this problem, arc welding or diffusion bonding processes can be used to process millimeter-wave waveguide slot antennas, but this will lead to high costs.

[0003] The proposed slot waveguide technology solves this problem well. This waveguide structure is composed of metal plates placed in parallel with a spacing less than 1 / 4 wavelength. One of them is a smooth metal plate, and the other metal plate is composed of an intermediate transmission structure and the surface of metal pin beds on both sides. Since the upper and lower metal plates of this structure can confine the electromagnetic energy transmission without electrical contact and do not generate outward diffusion, it achieves a transmission effect similar to that of a closed metal waveguide structure, reducing the processing and assembly difficulties.

[0004] Due to the increasing requirements for the volume of existing millimeter-wave radar systems, the antenna needs to achieve high gain at a smaller size. The back cavity slot array antenna is usually composed of radiation slots, resonant cavities, and a feeding network. It has a low profile and a compact structure, can achieve high gain, and at the same time, the efficiency of the back cavity slot array antenna can be improved by designing high-gain antenna elements and low-loss feeding networks.

[0005] When multiple back cavity sub-arrays arranged in a one-dimensional linear array or a two-dimensional planar array at a certain spacing are excited by a feeding network, a back cavity slot array antenna with high gain and low sidelobe level characteristics can be obtained. A single back cavity sub-array usually uses the method of bottom slot coupling feeding to excite 2×2 radiation slots. The back cavity slot antenna sub-array uses the method of bottom slot coupling feeding to excite four radiation slots. And in order to obtain in-phase excitation for the four radiation slots, the four radiation slots are symmetrically distributed around the coupling slot. When multiple back cavity sub-arrays arranged in a one-dimensional linear array or a two-dimensional planar array at a certain spacing are excited by a feeding network, a back cavity array antenna with high gain and low sidelobe level characteristics can be obtained.

[0006] For a cavity-backed slot array antenna formed by arranging elements in a one-dimensional linear array, amplitude weighting can be achieved by controlling the feeding network in the array direction, thereby realizing a low sidelobe level. However, in the direction perpendicular to the array, since there are only two radiating slots, amplitude weighting cannot be performed, resulting in a poor sidelobe level and a wide beamwidth, leading to a loss of antenna efficiency. Summary of the Invention

[0007] Aiming at the technical problems existing in the prior art, the present invention provides a radiating cavity unit and an array antenna of a cavity-backed slot array antenna with improved antenna gain and efficiency.

[0008] To solve the above technical problems, the technical solution proposed by the present invention is as follows:

[0009] A radiating cavity unit of a cavity-backed slot array antenna includes an upper metal plate, a plurality of radiating slots, an open cavity, a lower metal plate, more than one coupling slot, and a plurality of metal posts;

[0010] Through holes are formed on the lower metal plate to form coupling slots, and a plurality of metal posts are arranged around the periphery of the coupling slots;

[0011] A plurality of the radiating slots are located on the upper metal plate and on both sides of the coupling slot; the open cavity is located on the upper metal plate and on both sides of the coupling slot; the radiating slots on the same side of the coupling slot are located in the same open cavity.

[0012] Preferably, the open cavity is a rectangular cavity, the center line of the narrow side of the rectangular cavity is collinear with the center axis of the narrow side of the radiating slot, and the center line of the wide side is collinear with the center axes of the two radiating slots.

[0013] Preferably, the open cavity is an elliptical cavity.

[0014] Preferably, the number of the radiating slots is four, symmetrically distributed around the coupling slot; the number of the open cavities is two, symmetrically distributed on both sides of the coupling slot.

[0015] Preferably, the number of the coupling slots is multiple, and the multiple coupling slots are arranged in sequence on the lower metal plate along the long axis direction thereof.

[0016] Preferably, metal modules are loaded at the center lines of the radiating slots at both ends in the same open cavity.

[0017] Preferably, the metal posts include square metal posts and rectangular metal posts, the square metal posts are located around the coupling slot, and the rectangular metal posts are located at both ends of the coupling slot.

[0018] The present utility model also discloses a gap waveguide back cavity slot array antenna, which includes a plurality of radiation back cavity units of the gap waveguide back cavity slot array antenna as described above, a 6-way to 12-way power divider network layer, and a 1-way to 6-way power divider network layer; the plurality of radiation back cavity units are arranged at equal intervals in sequence; the radiation back cavity units, the 6-way to 12-way power divider network layer, and the 1-way to 6-way power divider network layer are arranged one above the other in sequence.

[0019] Preferably, the upper metal plate, the lower metal plate of the radiation back cavity unit, the 6-way to 12-way power divider network layer, and the 1-way to 6-way power divider network layer are connected by screws.

[0020] Compared with the prior art, the advantages of the present utility model are as follows:

[0021] In the present utility model, rectangular cavities are loaded around two radiation slots in the non-array direction, and the center lines of the rectangular cavities are collinear with the center lines of the two radiation slots. By loading open rectangular cavities, the beam width of the radiation pattern is reduced, the sidelobe level is optimized, the gain and efficiency of the back cavity slot array antenna are improved, and the antenna structure is simple and the cost is low. Description of the Drawings

[0022] Figure 1 It is a schematic structural diagram of the radiation back cavity unit of the present utility model in an embodiment.

[0023] Figure 2 It is a schematic structural diagram of the dual-radiation back cavity unit of the present utility model in an embodiment.

[0024] Figure 3 It is the H-plane normalized radiation pattern of the radiation back cavity unit of the present utility model and the traditional back cavity unit.

[0025] Figure 4 It is a structural diagram of the gap waveguide back cavity slot array antenna of the present utility model in an embodiment.

[0026] Figure 5 It is a top view of the radiation slot layer of the gap waveguide back cavity slot array antenna of the present utility model in an embodiment.

[0027] Figure 6 It is a rear view of the radiation slot layer of the gap waveguide back cavity slot array antenna of the present utility model in an embodiment.

[0028] Figure 7 It is a top view of the resonant cavity layer of the gap waveguide back cavity slot array antenna of the present utility model in an embodiment.

[0029] Figure 8 It is a rear view of the resonant cavity layer of the gap waveguide back cavity slot array antenna of the present utility model in an embodiment.

[0030] Figure 9This is the top view of the 1-to-6 power divider network layer of the gap waveguide back cavity slot array antenna of the present utility model in the embodiment.

[0031] Figure 10 This is the rear view of the 1-to-6 power divider network layer of the gap waveguide back cavity slot array antenna of the present utility model in the embodiment.

[0032] Figure 11 This is the top view of the 6-to-12 power divider network layer of the gap waveguide back cavity slot array antenna of the present utility model in the embodiment.

[0033] Figure 12 This is the port return loss diagram of the gap waveguide back cavity slot array antenna of the present utility model.

[0034] Figure 13 This is the radiation pattern in the center frequency direction of the gap waveguide back cavity slot array antenna of the present utility model.

[0035] Figure 14 This is the efficiency diagram of the gap waveguide back cavity slot array antenna of the present utility model.

[0036] Legend: 111, upper metal plate; 112, radiation slot; 113, open rectangular cavity; 114, lower metal plate; 115, coupling slot; 116, square metal column; 117, rectangular metal column; 118, metal module; 21, radiation slot layer; 213, first annular step; 214, first screw hole position; 215, second annular step; 216, first positioning pin hole position; 22, resonant cavity layer; 224, second screw hole position; 225, second positioning pin hole position; 226, third annular step; 23, 6-to-12 power divider network layer; 231, power divider coupling slot; 232, first coupling platform; 233, first T-shaped open end; 234, first metal column; 235, first cut angle on the ridge; 236, third screw hole position; 237, third positioning pin hole position; 238, fourth annular step; 24, 1-to-6 power divider network layer; 241, standard waveguide port; 242, second coupling platform; 243, second T-shaped open end; 244, second metal column; 245, second cut angle on the ridge; 246, fourth screw hole position; 247, fourth positioning pin hole position. Detailed implementation manners

[0037] The present utility model will be further described below in conjunction with the accompanying drawings of the specification and specific embodiments.

[0038] As Figure 1As shown in the figure, the radiation back cavity unit of the high-efficiency gap waveguide back cavity slot array antenna applied to FOD monitoring in the embodiment of the present utility model includes an upper back cavity metal plate 111, a radiation slot 112, an open rectangular cavity 113, a lower back cavity metal plate 114, a coupling slot 115, a square metal column 116, and a rectangular metal column 117;

[0039] This back cavity sub-array structure has four radiation slots 112, symmetrically distributed around the coupling slot 115, and each open rectangular cavity 113 surrounds two radiation slots 112; A plurality of metal columns arranged in a cycle surround the coupling slot 115. The square metal column 116 and the rectangular metal column 117 are raised structures on the lower back cavity metal plate 114, and electrical contact is achieved among the three.

[0040] The lower metal plate 114, the square metal column 116, and the rectangular metal column 117 together form the back cavity structure. The coupling slot 115 is a through hole on the lower metal plate 114, and it is located at the center of the back cavity.

[0041] By adjusting the length and width of the back cavity area, the resonance frequency of the TE 120 mode is near the center operating frequency, and then by adjusting the length of the metal column, the resonance frequencies of the TE 120 mode and other modes are isolated.

[0042] In specific applications, electromagnetic waves are coupled into the back cavity structure through the coupling slot 115 and finally radiated into the outer space through the four radiation slots 112 on the upper metal plate 111; The four radiation slots 112 are symmetrically distributed around the coupling slot 115, and the distance between the radiation slots 112 is less than one wavelength. When the operating mode in the back cavity is TE 120When in the mode, the directions of the currents cut by the four radiation slots 112 on the lower surface of the upper metal plate 111 are the same, and they have the same radiation ability and the same radiation phase. In this case, the radiation energy is the highest at the central positions of the respective radiation slots 112, while the energy at the middle positions between the two radiation slots 112 is weak, resulting in poor sidelobe levels. At this time, open rectangular cavities 113 are loaded around two radiation slots 112 on the same side of the coupling slot 115. The open rectangular cavities 113 are formed by digging down a certain depth on the upper metal plate 111. The energy radiated by the radiation slots 112 enters the open rectangular cavities 113. The width of the open rectangular cavities 113 is less than half a wavelength. By increasing the length of the open rectangular cavities 113, partial energy is coupled and excited at the longitudinal two-side positions of the open rectangular cavities 113 and radiated into the space; by optimizing the length and depth of the open rectangular cavities 113, the radiation energy at the central position of the open rectangular cavities 113, the central position of the radiation slots 112, and the longitudinal two-side positions of the open rectangular cavities 113 decreases successively from high to low, and its amplitude value is close to the Chebyshev distribution or the Taylor distribution, realizing the low sidelobe level characteristic. At the same time, because the effective radiation area extends from the two radiation slots 112 to the open rectangular cavities 113, it causes the beam width of the H-plane pattern to decrease, and the reduction of the sidelobe level and the beam width together achieve the gain improvement, as Figure 3 shown.

[0043] Specifically, the open rectangular cavities 113 can reduce the beam width of the H-plane pattern of the back cavity slot array antenna, reduce the sidelobe level of the H-plane pattern, and improve the gain and efficiency of the back cavity slot array antenna. Among them, the open rectangular cavities 113 surround two radiation slots 112 on the same side of the coupling slot 115; when the thickness of the upper metal plate 111 remains unchanged, if the depth of the open rectangular cavities 113 increases, the thickness of the radiation slots 112 decreases. The depth of the open rectangular cavities 113 affects the sidelobe level of the H-plane pattern, the length affects the beam width of the H-plane pattern, and the width of the open rectangular cavities 113 affects the impedance matching of the antenna. In the present invention, in order to make the H-plane beam width less than 24° and the sidelobe level better than -20 dB, after optimization, the depth of the open rectangular cavities 113 is 1 mm, the length is 7.8 mm, and the width is 1.3 mm. During the specific design, the dimensions of the open rectangular cavities 113 need to be reasonably optimized according to actual requirements to achieve good performance.

[0044] In addition, the center line of the narrow side of the open rectangular cavity 113 is collinear with the center line of the narrow side of the radiation slot 112, and the center line of the wide side is collinear with the central axis of the two radiation slots 112. Of course, in other embodiments, the open rectangular cavity 113 can also be elliptical.

[0045] Specifically, four radiation slots 112 with the same size are symmetrically distributed around the coupling slot 115. To achieve good radiation ability, the length of the radiation slot 112 in the present invention is 2.2 mm and the width is 1 mm.

[0046] Specifically, the square metal columns 116 are arranged periodically at a certain interval to form a high-impedance surface. In the present invention, the interval between two adjacent metal columns is about one-quarter of the free-space wavelength, and the height of the metal column is about one-quarter of the free-space wavelength. There is electrical contact between the metal column and the lower metal plate 114, and the gap between the metal column and the upper metal plate 111 is much smaller than one-quarter of the free-space wavelength. In this embodiment, the shape of the metal column is not limited. For example, the shape of the metal column can be a cuboid, a cylinder or other shapes, and there is no matching relationship with the shape of the open rectangular cavity 113 and the radiation slot 112. Among them, for the rectangular metal column 117, its length will affect the frequency interval between the resonance frequencies of two adjacent modes in the back cavity.

[0047] Specifically, the coupling slot 115 is a rectangular through-hole on the lower metal plate 114 and is located at the center of the back cavity area surrounded by the square metal columns 116. In this embodiment, the shape of the coupling slot 115 is not limited. For example, the shape of the coupling slot 115 can be rectangular, elliptical or dumbbell-shaped, etc.

[0048] Such as Figure 2As shown, the embodiment of the present utility model also discloses a double-back cavity slot array structure. The same two back cavity sub-arrays as described above are arranged along the long side direction of the radiation slot 112. The distance between the two back cavity sub-arrays is twice the distance between the radiation slots 112. Therefore, the four radiation slots 112 are equally spaced and have the same size in this direction. From the single-back cavity structure, it can be known that the four radiation slots 112 have the same radiation phase and the same radiation ability. For the double-back cavity structure, if the two coupling slots 115 are excited by currents with equal amplitude and the same phase, then the eight radiation slots 112 have the same radiation phase and the same radiation ability. The four radiation slots 112 arranged collinearly have the same radiation ability, and the surface current is evenly distributed in the same phase, resulting in a poor sidelobe level, about -13 dB. At this time, an open rectangular cavity 113 is loaded to surround the four radiation slots 112 arranged collinearly and equally spaced. The length and depth of the open rectangular cavity 113 are optimized so that the energy radiated at the center position of the open rectangular cavity 113, the center position of the radiation slot 112, and the two sides of the open rectangular cavity 113 decreases in order from high to low. However, the energy radiated at the center positions of the four radiation slots 112 is still the same at this time. At this time, metal modules 118 are loaded at the two sides of the open rectangular cavity 113 and at the center line of the first radiation slot 112 and the fourth radiation slot 112. The metal modules 118 reduce the radiation ability of the first and fourth radiation slots 112, so that the energy in the radiation area of the open rectangular cavity 113 decreases from the center position to both sides in order, and its amplitude distribution is close to the Chebyshev distribution or the Taylor distribution, realizing the low sidelobe level characteristic. At the same time, because the effective radiation area is extended from the four radiation slots 112 to the open rectangular cavity 113, the beam width of the H-plane pattern decreases, and the combined effect of the decrease in the sidelobe level and the decrease in the beam width realizes the gain improvement.

[0049] Specifically, in the two back cavity sub-arrays arranged longitudinally, the same two back cavity sub-arrays are arranged along the long side direction of the radiation slot 112, forming a 4×2 array surface of the radiation slots 112. The four radiation slots 112 arranged longitudinally are equally spaced. If the radiation slots 112 of the two back cavity sub-arrays are excited by currents with equal amplitude and the same phase, then the eight radiation slots 112 will have the same radiation ability, and the H-plane pattern is about -13 dB.

[0050] When applied to a double-back cavity sub-array structure, the open rectangular cavity 113 surrounds four radiation slots 112 arranged longitudinally collinearly and equidistantly, and metal modules 118 are loaded at the positions on both sides of the open rectangular cavity 113 and at the center lines of the first radiation slot 112 and the fourth radiation slot 112. The metal module 118 can be a cuboid, a semi-cylindrical body or a cone. By optimizing the length and depth of the open rectangular cavity 113, the radiation energy at the center position of the open rectangular cavity 113, the center position of the radiation slot 112, and the positions on both sides of the open rectangular cavity 113 decreases successively from strong to weak. Increasing the length and width of the metal module 118 can further reduce the radiation capabilities of the first radiation slot 112 and the fourth radiation slot 112, thereby reducing the H-plane sidelobe level of the back cavity slot array antenna and decreasing the beam width of the H-plane pattern, and improving the antenna gain and efficiency.

[0051] Based on the existing technology of the back cavity slot array antenna, the present utility model loads an open rectangular cavity 113 around two radiation slots 112 in the non-array direction. By adjusting the dimensions of the open rectangular cavity 113 and the radiation slots 112, the beam width of the pattern is reduced and the sidelobe level is decreased, further improving the efficiency of the back cavity slot array antenna.

[0052] As Figure 4 shown, an embodiment of the present utility model further discloses a high-efficiency gap waveguide back cavity slot array antenna, which is composed of a plurality of Figure 1 back cavity sub-arrays shown arranged linearly at equal intervals. The back cavity slot array antenna specifically includes a radiation slot layer 21 (corresponding to the upper metal plate 111), a resonant cavity layer 22 (corresponding to the lower metal plate 114), a 6-way to 12-way power divider network layer 23, and a 1-way to 6-way power divider network layer 24;

[0053] The radiation slot layer 21 includes radiation slots 112, open rectangular cavities 113, first annular steps 213, first screw hole positions 214, second annular steps 215 on the back, and first positioning pin hole positions 216, as Figure 5 - Figure 6 shown;

[0054] The resonant cavity layer 22 includes coupling slots 115, periodically arranged square metal columns 116, rectangular metal columns 117, second screw hole positions 224, second positioning pin hole positions 225, and third annular steps 226 on the back, as Figure 7 - Figure 8 shown;

[0055] The 6-way to 12-way power divider network layer includes power divider coupling slots 231, first coupling platforms 232, first T-shaped open ends 233, periodically arranged first metal columns 234, first ridge cut corners 235, third screw hole positions 236, third positioning pin hole positions 237, and fourth annular steps 238 on the back, as Figure 9 - Figure 10 shown;

[0056] The 1-way 6-way power divider network layer includes a standard waveguide port 241, a second coupling platform 242, a second T-shaped open end 243, periodically arranged second metal posts 244, a second ridge chamfer 245, a fourth screw hole position 246, and a fourth positioning pin hole position 247, as Figure 11 shown.

[0057] The operating frequency range of the above antenna is 92 - 94 GHz, and the operating wavelength is between 3.19 - 3.26 mm. The overall performance index of the antenna requires that the E-plane half-power beamwidth of the antenna is about 3°. Therefore, about 12 back cavity sub-arrays are required to be arranged in an equally spaced period to form a 2 * 24 radiation slot array. The condition for the antenna pattern not to have grating lobes is (where θ is the beam scanning angle, d is the spacing between adjacent radiation units, and λ is the wavelength in free space), but the antenna in this embodiment has no beam scanning requirement. Therefore, the slot spacing is less than one free space wavelength λ. Considering the processing difficulty and the radiation ability of the antenna, the spacing d y between two adjacent radiation slots 112 in the y direction = 2.5 mm < 0.8λ, and the spacing between two adjacent back cavity sub-arrays is 5 mm. The spacing d x between two radiation slots 112 in the x direction = 2.6 mm.

[0058] In this embodiment, the beamwidth requirement of the E-plane pattern of the back cavity slot array antenna is about 3°. Therefore, 12 back cavity sub-array units are arranged in the y direction to form a 2 * 24 radiation array surface to meet the beamwidth requirement. Through the bottom weighted power divider feeding network, 12 coupling slots 115 are coupled to excite the 12 back cavity sub-array units with in-phase unequal-amplitude currents, realizing the low sidelobe level characteristic of the E-plane pattern. The weighted power divider feeding network is composed of cascaded multi-stage 1-way 2-way unequal power dividers. To reduce the lateral size of the antenna, the weighted power divider feeding network is divided into two-layer structures, namely the 1-way 6-way power divider network layer 24 and the 6-way 12-way power divider network layer 23. To meet the -30 dB Taylor weighted distribution to realize the low sidelobe characteristic of the E-plane pattern, each stage of the power divider in the weighted power divider feeding network meets a specific power division ratio.

[0059] In this embodiment, the energy is fed into from the standard waveguide port 241 and equally divided and transmitted into the ridge gap waveguide. After passing through two stages of 1-way 2-way unequal power dividers, 1-way 6-way unequal power division is realized, and it is coupled to the 6-way 12-way power divider network layer through the end second T-shaped open end 243 and the power divider coupling slot 231. Then, through 6 1-way 2-way unequal power dividers, 12 first T-shaped open ends 233, and the corresponding coupling slots 115, 12 back cavity sub-array units are coupled and excited, and finally radiated into the outer space through the radiation slots 112, realizing the low sidelobe characteristic of the antenna E-plane pattern.

[0060] Each level of unequal power divider is composed of a first coupling platform 232, a second coupling platform 242, an intermediate input ridge, and two output ridges on both sides. The power division ratio of the power divider is controlled by the length of the output ridge extending into the coupling platform and the height of the coupling platform. A ridge-gap waveguide transmission line structure is formed by periodically arranged second metal columns 244, first metal columns 234, and an intermediate ridge. Second ridge chamfers 245 and first ridge chamfers 235 are made on the ridges at the right-angle bends to reduce the reflection of energy here.

[0061] A coupling slot 115 excites four radiation slots 112 symmetrically distributed around it, and a back cavity structure is formed by several periodically arranged metal columns. To enable the four radiation slots 112 to be excited by currents with equal amplitude and in the same phase, the size of the back cavity needs to be adjusted so that the resonance frequency of the TE 120 mode in the back cavity is the center operating frequency of the antenna. There are only two radiation slots 112 in the x direction and they are excited by currents with equal amplitude and in the same phase. Therefore, the sidelobe level of the H-plane radiation pattern is approximately -13 dB, the half-power beamwidth is approximately 30°, and the antenna radiation efficiency is approximately 80%.

[0062] To reduce the sidelobe level of the H-plane radiation pattern and decrease the beamwidth, open rectangular cavities 113 are loaded around the two radiation slots 112 in the x direction. The centerlines of the open rectangular cavities 113 are collinear with the centerlines of the radiation slots 112. Due to the presence of the open rectangular cavities 113, the energy radiated through the radiation slots 112 is further radiated into free space by the open rectangular cavities 113. The radiation energy at the center of the open rectangular cavities 113 is higher, and the radiation energy outside the rectangular cavities is weaker, realizing the low-sidelobe characteristic of the radiation pattern. At the same time, due to the expansion of the effective radiation area, the H-plane half-power beamwidth is further decreased, and the antenna gain and efficiency are improved.

[0063] Considering processing and assembly, and to improve the isolation between two antennas, a first annular step 213 is designed in the outer region of the radiation slot layer 21 of the back cavity slot array antenna. The height of the annular step and the width of the inner ring will affect the antenna radiation performance. Therefore, the size of the open rectangular cavity 113 needs to be further optimized to improve the antenna radiation performance.

[0064] In order to achieve the fixed assembly of the four-layer structure of the antenna, fixing first screw hole positions 214, second screw hole positions 224, third screw hole positions 236, fourth screw hole positions 246, as well as first positioning pin hole positions 216, second positioning pin hole positions 225, third positioning pin hole positions 237 and fourth positioning pin hole positions 247 are respectively provided on each layer structure. At the same time, an annular step is provided on the back of each layer, and the width of the step is greater than the diameter of the fixing screw hole positions, so as to enable the layers to be closely connected. As the radar front end, this antenna needs to consider the fixed connection with other modules. For the convenience of installation, the antenna is fixedly connected with other modules by means of screws penetrating the antenna from the front of the antenna downward; at the same time, in order to prevent the screws from protruding from the antenna radiation array surface, rectangular through holes are made in the radiation slot layer 21 and the resonant cavity layer 22, circular through holes are made on the 6-way 12-way power dividing network layer 23 as screw hole positions, and a rectangular step and a circular through hole are made on the 1-way 6-way power dividing network layer 24.

[0065] The present utility model reduces the H-plane pattern sidelobe level and reduces the beam width by loading an open rectangular cavity 113 around the antenna radiation slot 112, and cooperates with a weighted power dividing feed network to realize the low sidelobe level characteristic of the E-plane pattern, realizing a gap waveguide back cavity slot array antenna with low sidelobes, high efficiency, simple structure and low cost, which can be applied to FOD monitoring equipment.

[0066] From Figure 12 - Figure 14 As can be seen from the shown simulation results, the antenna port of the present utility model has good return loss characteristics, and satisfies S11 < -10 dB in the frequency band range of 91 - 96 GHz. The antenna gain at 93 GHz is 26.2 dB, the H-plane beam width is 23.3°, the first sidelobe level of the H-plane is -23.4 dB, the E-plane beam width is 3.3°, the first sidelobe level of the E-plane is -25.6 dB, and the antenna efficiency reaches 94.2%. The antenna efficiency is greater than 93% in the entire working frequency band.

[0067] The present utility model can realize a low-cost high-gain back cavity slot array antenna by arranging multiple back cavity units in an equidistant one-dimensional linear arrangement and then exciting them through a weighted power dividing feed network.

[0068] The present utility model arrays multiple back cavity units in the E-plane. Due to the existence of the power dividing feed network, the low sidelobe level characteristic of the E-plane pattern can be realized. For the H-plane, since there are only two radiation slots 112, it is impossible to realize the amplitude weighted distribution. Therefore, the beam width of the H-plane pattern is reduced and the sidelobe level of the H-plane pattern is reduced by loading a rectangular cavity. One rectangular cavity surrounds two radiation slots 112 arranged in the H-plane; in the double back cavity structure, one rectangular cavity surrounds four radiation slots 112 arranged in the H-plane, and four metal modules 118 are added in the rectangular cavity.

[0069] In the non-array direction of the present utility model, rectangular cavities are loaded around two radiation slots 112. The center lines of the rectangular cavities are collinear with the center lines of the two radiation slots 112. By loading the rectangular cavities, the beam width of the radiation pattern is reduced, the sidelobe level is optimized, the gain and efficiency of the back cavity slot array antenna are improved, and the antenna structure is simple and the cost is low.

[0070] The present utility model can be applied to millimeter-wave radar application scenarios such as FOD, automotive radar, airborne / missile-borne early warning radar, etc.

[0071] The above is only the preferred embodiment of the present utility model, and the protection scope of the present utility model is not limited to the above embodiments. All technical solutions falling within the idea of the present utility model belong to the protection scope of the present utility model. It should be pointed out that for those of ordinary skill in the art in this technical field, several improvements and refinements made without departing from the principle of the present utility model should be regarded as the protection scope of the present utility model.

Claims

1. A radiation back cavity unit of a gap waveguide back cavity slot array antenna, characterized in that: It comprises an upper metal plate (111), a plurality of radiation slots (112), an open cavity, a lower metal plate (114), more than one coupling slot (115) and a plurality of metal columns; The lower metal plate (114) is provided with a through hole to form a coupling gap (115), and a plurality of metal columns are arranged around the coupling gap (115); The plurality of radiation slots (112) are located on the upper metal plate (111) and on both sides of the coupling slot (115); the open cavity is located on the upper metal plate (111) and on both sides of the coupling slot (115); and the radiation slots (112) on the same side of the coupling slot (115) are located in the same open cavity.

2. The radiation back cavity unit of the gap waveguide back cavity slot array antenna according to claim 1, characterized in that: The open cavity is a rectangular cavity, the narrow side center line of the rectangular cavity is collinear with the narrow side center axis of the radiation slot (112), and the wide side center line is collinear with the center axes of the two radiation slots (112).

3. The radiation back cavity unit of the gap waveguide back cavity slot array antenna according to claim 1, characterized in that: The open cavity is an elliptical cavity.

4. The radiation back cavity unit of the gap waveguide back cavity slot array antenna according to claim 1, 2 or 3, characterized in that: The number of the radiation slots (112) is four, which are symmetrically distributed around the coupling slot (115); the number of the open chambers is two, which are symmetrically distributed on both sides of the coupling slot (115).

5. The radiation back cavity unit of the gap waveguide back cavity slot array antenna according to claim 1, 2 or 3, characterized in that: The coupling slots (115) are multiple in number, and the multiple coupling slots (115) are arranged in sequence on the lower metal plate (114) along the long axis direction thereof.

6. The radiation back cavity unit of the gap waveguide back cavity slot array antenna according to claim 5, characterized in that: Metal modules (118) are loaded at the center lines of the radiation gaps (112) at both ends of the same opening cavity.

7. The radiation back cavity unit of the gap waveguide back cavity slot array antenna according to claim 1, 2 or 3, characterized in that: The metal columns include square metal columns (116) and rectangular metal columns (117); the square metal columns (116) are located on the periphery of the coupling gap (115); and the rectangular metal columns (117) are located at both ends of the coupling gap (115).

8. A gap waveguide back cavity slot array antenna, characterized in that: It comprises a plurality of radiating back cavity units of the gap waveguide back cavity slot array antenna as described in any one of claims 1 to 7, a 6-to-12 power division network layer (23) and a 1-to-6 power division network layer (24); the plurality of radiating back cavity units are arranged in sequence with equal intervals; the radiating back cavity units, the 6-to-12 power division network layer (23) and the 1-to-6 power division network layer (24) are arranged in sequence up and down.

9. The gap waveguide cavity-backed slot array antenna according to claim 8, characterized in that: The upper metal plate (111), the lower metal plate (114), the 6-12 power division network layer (23) and the 1-6 power division network layer (24) of the radiation back cavity unit are connected by screws.

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