PCM-based low-RCS circularly polarized broadband array antenna

Abstract

The invention relates to the technical field of antennas, in particular to a PCM (pulse code modulation)-based low-RCS (radar cross section) circularly polarized broadband array antenna, which comprises four antenna units, the upper layer of each antenna unit is a 6 * 6 chessboard-shaped array formed by low-profile polarization conversion metasurface units, the array is loaded on a slotted slot antenna on a floor, and a microstrip line passes through a PCM structure on a slot excitation surface. The upper layer of the PCM unit is a double-inclined grooved square metal patch, the middle layer is a dielectric layer, and the lower layer is a grooved grounding metal plate. A feed network based on sequential rotation is used as a feed mode, and the feed network is composed of three one-to-two Wilkinson power dividers. Through verification, the impedance bandwidth is 5.1-9.3 GHz, and the reflection coefficient can reach-10dB and below. The peak gain in the maximum radiation direction of the antenna is 9.8 dBi at 8.8 GHz, and the 3dB axial ratio bandwidth range is 6.36-7.92 GHz. The RCS reduction frequency band range of more than 10dB is 7.1-15.6 GHz, the relative bandwidth is 74.9%, and the RCS reduction performance is good.

Description

Technical Field

[0001] The invention relates to the technical field of antennas, and in particular to a low RCS circularly polarized broadband array antenna based on PCM. Background Art

[0002] Radar cross section (RCS) is an important parameter for measuring electromagnetic stealth capability. By reducing the RCS of a target, the probability of radar detecting weapons and equipment can be significantly reduced. In stealth weapons and equipment used in actual combat, the RCS of the antenna accounts for a large proportion of the overall scattering, so reducing the RCS of the antenna is particularly critical. However, while reducing the RCS of the antenna, it is also necessary to maintain the stability of its radiation performance, which to a certain extent limits the use of RCS reduction methods.

[0003] In recent years, the rapid development of electromagnetic metamaterials, which have the characteristics of flexible control of electromagnetic waves, has provided new ideas for reducing antenna RCS. At present, most of the RCS reduction research still focuses on the 0dB bandwidth, while the 10dB RCS reduction bandwidth is narrow or only at certain frequency points. Summary of the invention

[0004] The object of the present invention is to provide a low RCS circularly polarized broadband array antenna based on PCM, wherein the reflection coefficient of the circularly polarized slot antenna array is kept below -10dB within the frequency range of 5.1-9.3GHz, and the circularly polarized slot antenna array has good circularly polarized radiation performance.

[0005] To achieve the above object, the present invention provides a low RCS circularly polarized broadband array antenna based on PCM, comprising four antenna units, which are arranged in a field shape;

[0006] Each antenna unit has a five-layer structure, which includes a metal patch, an upper dielectric substrate, a metal floor, a lower dielectric substrate and a feeding microstrip line from top to bottom. The metal patch, the upper dielectric substrate and the metal floor constitute a PCM unit, and the PCM unit is arranged in a 6×6 chessboard array. The feeding network formed by the feeding microstrip line consists of three one-to-two Wilkinson power dividers, and the isolation resistance R between the feeding microstrip lines is 100Ω.

[0007] The pattern of the upper metasurface of each PCM unit is obtained by digging oblique grooves on the upper left and lower right of a square patch; the PCM units on two adjacent antenna units are arranged in mirror symmetry.

[0008] The metal floor of the antenna unit is slotted in the middle, the amplitudes of adjacent unit slots in the array are the same, and the phase distributions are 0°, 90°, 180°, and 270° respectively.

[0009] The upper dielectric substrate and the lower dielectric substrate are both made of F4B, but have different thicknesses.

[0010] The present invention provides a low RCS circular polarization broadband array antenna based on PCM, comprising four antenna units, the upper layer of which is a 6×6 chessboard array composed of low-profile polarization conversion metasurface units, which is loaded on a slot antenna slotted on the floor, and a microstrip line excites the PCM structure on the surface through the slot. The upper layer of the PCM unit is a double-slanted square metal patch, the middle is a dielectric layer, and the lower layer is a slotted grounded metal plate. The present invention uses a feeding network based on sequential rotation as a feeding method, and the feeding network consists of three one-to-two Wilkinson power dividers. It has been verified that the impedance bandwidth of the present invention is 5.1-9.3GHz, and the reflection coefficient can reach -10dB and below. The peak gain in the maximum radiation direction of the antenna is 9.8dBi at 8.8GHz, and the 3dB axial ratio bandwidth range is 6.36-7.92GHz. The RCS reduction band range of more than 10dB is 7.1-15.6GHz, and the relative bandwidth is 74.9%, which has good RCS reduction performance. BRIEF DESCRIPTION OF THE DRAWINGS

[0011] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0012] Figure 1 It is a front structural schematic diagram of a PCM-based low RCS circularly polarized broadband array antenna of the present invention.

[0013] Figure 2 It is a rear view of a PCM-based low RCS circularly polarized broadband array antenna of the present invention.

[0014] Figure 3 It is a side view of a PCM-based low RCS circularly polarized broadband array antenna of the present invention.

[0015] Figure 4 It is a front view of an antenna unit of a PCM-based low RCS circularly polarized broadband array antenna of the present invention.

[0016] Figure 5 It is a rear view of an antenna unit of a PCM-based low RCS circularly polarized broadband array antenna of the present invention.

[0017] Figure 6 It is a structural schematic diagram of a PCM unit of a PCM-based low RCS circularly polarized broadband array antenna of the present invention.

[0018] Figure 7 It is a schematic diagram of the reflection coefficient simulation and test result curve of the 2×2 circularly polarized array antenna in a specific embodiment of the present invention.

[0019] Figure 8 It is a schematic diagram of the maximum radiation direction gain curve and axial ratio curve of the circular polarization array antenna simulation and test in a specific embodiment of the present invention.

[0020] Fig. 9 It is a comparison diagram of axial ratio simulation and test of circular polarization array antenna simulation and test in a specific embodiment of the present invention.

[0021] Fig.10 It is a schematic diagram of single-station RCS simulation and test curves of the circularly polarized array antenna of PCM and the metal floor of the same size in a specific embodiment of the present invention. DETAILED DESCRIPTION

[0022] Embodiments of the present invention are described in detail below, examples of which are shown in the accompanying drawings, wherein the same or similar reference numerals throughout represent the same or similar elements or elements having the same or similar functions. The embodiments described below with reference to the accompanying drawings are exemplary and are intended to be used to explain the present invention, and should not be construed as limiting the present invention.

[0023] See also Figures 1 to 6 The present invention provides a low RCS circularly polarized broadband array antenna based on PCM, comprising four antenna units, and the four antenna units are arranged in a field shape;

[0024] Each antenna unit has a five-layer structure, which includes a metal patch, an upper dielectric substrate, a metal floor, a lower dielectric substrate and a feeding microstrip line from top to bottom. The metal patch, the upper dielectric substrate and the metal floor constitute a PCM unit, and the PCM unit is arranged in a 6×6 chessboard array. The feeding network formed by the feeding microstrip line consists of three one-to-two Wilkinson power dividers, and the isolation resistance R between the feeding microstrip lines is 100Ω.

[0025] Specifically, the overall size of the antenna unit is 60×60×3.8mm 3 The pattern of the upper metasurface of each PCM unit is obtained by digging oblique grooves on the upper left and lower right of a square patch; the PCM units on two adjacent antenna units are arranged in mirror symmetry.

[0026] The PCM unit and its mirror unit show the same reflection amplitude and a phase difference of 180°. By arranging the two units in a checkerboard pattern to form a metasurface array, the RCS is effectively reduced by using the principle of phase cancellation.

[0027] Furthermore, the feeding network consists of three one-to-two Wilkinson power dividers, where the isolation resistance between the microstrip lines is R=100Ω, and the two-layer dielectric substrate is made of F4B, with a relative dielectric constant of 2.2 and a dielectric loss tangent of 0.004. That is, the upper metasurface of the antenna array consists of 12×12 units. The thickness of the upper dielectric substrate is 3mm, and the lower layer is a 0.8mm thick substrate printed with a sequentially rotated feeding network. The feeding network excites four orthogonal slots, and the amplitudes of adjacent slots are the same, and the phase distributions are 0°, 90°, 180°, and 270°, respectively.

[0028] Finally, the polarization conversion metasurface array is loaded on Figure 5 In the slot antenna shown, a microstrip line is used to excite the PCM structure on the upper surface through the slot, and the PCM structure plays a role of radiation. Among them, the width of the microstrip line is w = 2.4 mm, the slot length is ls = 26 mm, and the distance from the top of the microstrip line to the center of the slot is lfs = 5 mm.

[0029] like Figure 6 The figure shows the structure and size of the PCM unit, which consists of three layers, from top to bottom, metal patch, upper dielectric substrate and metal floor. The upper metal patch is a square patch obtained by digging grooves on the upper left and lower right sides, and consists of two triangular metal patches on the upper left and lower right sides and a hexagonal metal patch in the middle. The distance between the triangular patch and the edge of the dielectric plate is g = 0.8mm, and the distance between the triangular patch and the center hexagonal patch is d = 1.2mm; the middle layer is a square dielectric substrate, made of F4B, with a side length of l = 10mm and a thickness of t = 3mm; the bottom layer is a fully covered metal floor.

[0030] In order to illustrate the benefits of the present invention, the present invention also uses simulation experiments for comparison:

[0031] like Figure 7 The reflection coefficient simulation and test result curves of the 2×2 circularly polarized array antenna are shown. The simulation results show that in the 5.1-9.3GHz frequency band, the impedance matching effect is good, and the reflection coefficient can reach -10dB and below. Comparing the test results with the simulation results, it is found that although the tested S11 curve is different from the simulation results at some frequency points, the overall curve trend and matching are consistent, and the impedance matching of the processed array antenna is good. The difference between the simulation and test results is mainly caused by the errors caused in the manufacturing process and the dielectric loss of the material.

[0032] like Figure 8The maximum radiation direction gain curve and axial ratio curve of the circular polarization array antenna simulation and test are shown. It can be seen from the figure that the simulation and test results are basically consistent. The maximum radiation direction peak gain of the antenna simulation is 11.5dBi at 8.8GHz, and the maximum gain of the test is also 9.8dBi at 8.8GHz. There is a certain error, but it is within an acceptable range.

[0033] like Fig. 9 The following is a comparison chart of the axial ratio simulation and test of the circular polarization array antenna. It can be seen from the figure that the simulation and test results are basically consistent. The 3dB axial ratio bandwidth of the antenna simulation is 6.36-7.92GHz. The axial ratio bandwidth of the test is 3dB higher than the simulation result at certain frequency points, but the overall axial ratio bandwidth frequency range is wider than the simulation result. The change in the test results is mainly caused by manufacturing errors and test errors, and the overall difference with the simulation results is small.

[0034] like Fig.10 The figure shows the RCS simulation and test curves of a single station of a circularly polarized array antenna loaded with PCM and a metal floor of the same size. It can be seen from the figure that the RCS of the antenna loaded with a chessboard PCM array has been effectively reduced. The RCS reduction frequency band range is 7.1-15.6GHz, and more than 10dB RCS reduction is achieved in this frequency band. The 10dB RCS relative bandwidth is 74.9%. Compared with the metal ground plane of the same area, the maximum RCS reduction value reaches 41.3dB. The measured data and the simulation results are basically consistent, indicating that the PCM structure has effectively reduced the scattering of the antenna.

[0035] In summary, the PCM-based low RCS circularly polarized broadband array antenna increases the 10dB RCS reduction bandwidth while improving the circular polarization axial ratio bandwidth of the antenna, maintaining a high gain, and ensuring excellent circular polarization radiation performance, thereby achieving effective RCS reduction.

[0036] What is disclosed above is only a preferred embodiment of the present invention, and it certainly cannot be used to limit the scope of rights of the present invention. Ordinary technicians in this field can understand that all or part of the processes of the above embodiment and equivalent changes made according to the claims of the present invention still fall within the scope of the invention.

Claims

1. A low RCS circularly polarized broadband array antenna based on PCM, characterized in that: It includes four antenna units, which are arranged in a field shape; Each antenna unit has a five-layer structure, which includes a metal patch, an upper dielectric substrate, a metal floor, a lower dielectric substrate and a feeding microstrip line from top to bottom. The metal patch, the upper dielectric substrate and the metal floor constitute a PCM unit, and the PCM unit is arranged in a 6×6 chessboard array. The feeding network formed by the feeding microstrip line consists of three one-to-two Wilkinson power dividers, and the isolation resistance R between the feeding microstrip lines is 100Ω.

2. The PCM-based low RCS circularly polarized broadband array antenna according to claim 1, characterized in that: The pattern of the upper metasurface of each PCM unit is obtained by digging oblique grooves on the upper left and lower right of a square patch; the PCM units on two adjacent antenna units are arranged in mirror symmetry.

3. The PCM-based low RCS circularly polarized broadband array antenna according to claim 2, characterized in that: The metal floor of the antenna unit is slotted in the middle, the amplitudes of adjacent unit slots in the array are the same, and the phase distributions are 0°, 90°, 180°, and 270° respectively.

4. The PCM-based low RCS circularly polarized broadband array antenna according to claim 3, characterized in that: The material of the upper dielectric substrate and the lower dielectric substrate are both F4B, but the thickness is different.

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