A PCM-based low RCS circularly polarized broadband array antenna

Abstract

This invention relates to the field of antenna technology, specifically to a low RCS circularly polarized broadband array antenna based on PCM, comprising four antenna elements. The upper layer of the antenna elements is a 6×6 checkerboard array composed of low-profile polarization conversion metasurface elements, loaded on a slotted antenna with slots in the ground plane. The PCM structure on the surface is excited by microstrip lines through the slots. The upper layer of the PCM element is a double-slotted square metal patch, the middle layer is a dielectric layer, and the lower layer is a slotted grounded metal plate. This invention uses a sequentially rotating feed network as the feeding method, and the feed network consists of three 1-to-2 Wilkinson power dividers. Verification shows that the impedance bandwidth of this 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 frequency band above 10dB is 7.1-15.6GHz, with a relative bandwidth of 74.9%, exhibiting excellent RCS reduction performance.

Description

Technical Field

[0001] This invention relates to the field of antenna technology, and more specifically to a low RCS circularly polarized broadband array antenna based on PCM. Background Technology

[0002] Radar cross section (RCS) is a crucial parameter for measuring electromagnetic stealth capabilities. Reducing a target's RCS can significantly decrease the probability of radar detection of weapons and equipment. In stealth weapons and equipment used in actual combat, the antenna's RCS accounts for a large proportion of the overall scattering, making its reduction particularly critical. However, while reducing the antenna's RCS, it is also necessary to maintain the stability of its radiation performance, which to some extent limits the application of RCS reduction methods.

[0003] In recent years, the rapid development of electromagnetic metamaterials, due to their ability to flexibly control electromagnetic waves, has provided new ideas for reducing antenna RCS. Currently, most research on RCS reduction still focuses on the 0dB bandwidth, while 10dB RCS reduction has a narrow bandwidth or only occurs at certain frequency points. Summary of the Invention

[0004] The purpose of this invention is to provide a low RCS circularly polarized broadband array antenna based on PCM, in which the reflection coefficient of the circularly polarized slot antenna array is kept below -10dB in the frequency range of 5.1-9.3GHz, while having good circularly polarized radiation performance.

[0005] To achieve the above objectives, the present invention provides a low RCS circularly polarized broadband array antenna based on PCM, comprising four antenna elements arranged in a grid pattern.

[0006] Each antenna element has a five-layer structure, consisting of a metal patch, an upper dielectric substrate, a metal ground plane, a lower dielectric substrate, and a feed microstrip line from top to bottom. The metal patch, upper dielectric substrate, and metal ground plane constitute a PCM unit, which is arranged in a 6×6 checkerboard array. The feed network formed by the feed microstrip line consists of three Wilkinson power dividers with a 1-to-2 splitter configuration. The isolation resistance between the feed microstrip lines is R = 100Ω.

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

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

[0009] Both the upper and lower dielectric substrates are made of F4B, but their thicknesses differ.

[0010] This invention provides a low RCS circularly polarized broadband array antenna based on PCM, comprising four antenna elements. The upper layer of the antenna elements is a 6×6 checkerboard array composed of low-profile polarization conversion metasurface elements, loaded on a slotted antenna with slots in the ground plane. The PCM structure on the surface is excited by microstrip lines through the slots. The upper layer of the PCM element is a double-slotted square metal patch, the middle layer is a dielectric layer, and the lower layer is a slotted grounded metal plate. This invention uses a sequentially rotating feed network as the feeding method, and the feed network consists of three 1-to-2 Wilkinson power dividers. Verification shows that the impedance bandwidth of this invention is 5.1-9.3GHz, and the reflection coefficient can reach -10dB or 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 frequency band above 10dB is 7.1-15.6GHz, with a relative bandwidth of 74.9%, exhibiting excellent RCS reduction performance. Attached Figure Description

[0011] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

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

[0013] Figure 2 This is a rear view of a low RCS circularly polarized broadband array antenna based on PCM according to the present invention.

[0014] Figure 3 This is a side view of a low RCS circularly polarized broadband array antenna based on PCM according to the present invention.

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

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

[0017] Figure 6 This is a schematic diagram of the PCM unit of a low RCS circularly polarized broadband array antenna based on PCM according to the present invention.

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

[0019] Figure 8 This is a schematic diagram of the maximum radiation direction gain curve and axial ratio curve of the circularly polarized array antenna simulation and testing in a specific embodiment of the present invention.

[0020] Figure 9 This is a comparison chart of axial ratio simulation and testing of circularly polarized array antenna in a specific embodiment of the present invention.

[0021] Figure 10 This is a schematic diagram of the single-station RCS simulation and test curves of the circularly polarized array antenna of the PCM and the metal ground plane of the same size in a specific embodiment of the present invention. Detailed Implementation

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

[0023] Please see Figures 1 to 6 The present invention provides a low RCS circularly polarized broadband array antenna based on PCM, comprising four antenna elements arranged in a grid pattern.

[0024] Each antenna element has a five-layer structure, consisting of a metal patch, an upper dielectric substrate, a metal ground plane, a lower dielectric substrate, and a feed microstrip line from top to bottom. The metal patch, upper dielectric substrate, and metal ground plane constitute a PCM unit, which is arranged in a 6×6 checkerboard array. The feed network formed by the feed microstrip line consists of three Wilkinson power dividers with a 1-to-2 splitter configuration. The isolation resistance between the feed microstrip lines is R = 100Ω.

[0025] Specifically, the overall dimensions of the antenna unit are 60×60×3.8mm. 3 The pattern on the upper metasurface of each PCM unit is obtained by cutting out square patches at the upper left and lower right corners; the PCM units on two adjacent antenna units are arranged in a mirror-symmetric manner.

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

[0027] Furthermore, the feed network consists of three Wilkinson power dividers (1 to 2), with an isolation resistance R = 100Ω between the microstrip lines. The two dielectric substrates are made of F4B material, with a relative permittivity of 2.2 and a dielectric loss tangent of 0.004. That is, the upper metasurface of the antenna array consists of 12×12 elements. The upper dielectric substrate is 3mm thick, and the lower layer is a 0.8mm thick substrate with a sequentially rotated feed network. This feed network excites four orthogonal slots, with adjacent slots having the same amplitude and phase distributions of 0°, 90°, 180°, and 270°, respectively.

[0028] Finally, the polarization conversion metasurface array is loaded onto, as... Figure 5 The slot antenna shown uses a microstrip line to excite the PCM structure on the upper surface through the slot, where the PCM structure acts as a radiator. The microstrip line width 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 diagram shows the structure and dimensions of a PCM cell, which consists of three layers: a metal patch, an upper dielectric substrate, and a metal ground plane. The upper metal patch is a square patch with oblique grooves cut out at the upper left and lower right. It comprises two triangular metal patches at the upper left and lower right, and a central hexagonal metal patch. The distance between the triangular patches and the edge of the dielectric substrate is g = 0.8 mm, and the distance between the triangular patches and the central hexagonal patch is d = 1.2 mm. The middle layer is a square dielectric substrate made of F4B, with a side length l = 10 mm and a thickness t = 3 mm. The bottom layer is a fully covered metal ground plane.

[0030] To illustrate the advantages of this invention, simulation experiments are also used for comparison and explanation:

[0031] like Figure 7 Simulation and test results of the reflection coefficient of a 2×2 circularly polarized array antenna are presented. Simulation results show that impedance matching is good within the 5.1-9.3 GHz frequency band, and the reflection coefficient can reach -10 dB or below. Comparison of test and simulation results reveals that although the tested S11 curve differs from the simulation result at certain frequency points, the overall curve trend and matching are consistent. Furthermore, the impedance matching of the fabricated array antenna is good. The differences between the simulation and test results are mainly caused by manufacturing errors and dielectric losses in the materials.

[0032] like Figure 8The figure shows the maximum radiation direction gain curve and axial ratio curve of the simulated and tested circularly polarized array antenna. As can be seen from the figure, the simulation and test results are in good agreement. The simulated maximum radiation direction peak gain is 11.5 dBi at 8.8 GHz, while the tested maximum gain is also 9.8 dBi at 8.8 GHz. There is some error, but it is within an acceptable range.

[0033] like Figure 9 The figure shows a comparison of the axial ratio simulation and test results for the circularly polarized array antenna. As can be seen from the figure, the simulation and test results are basically in agreement. The simulated 3dB axial ratio bandwidth range is 6.36-7.92GHz. Compared with the simulation results, the tested axial ratio bandwidth is 3dB higher at a few frequency points, but the overall axial ratio bandwidth frequency range is wider than the simulation results. The variations in the test results are mainly due to manufacturing errors and testing errors, and the overall difference from the simulation results is small.

[0034] like Figure 10 The figure shows the simulated and tested RCS curves of a single-site circularly polarized array antenna with a PCM array and an equivalent-sized metal ground plane. As can be seen from the figure, the RCS of the antenna with the checkerboard PCM array is effectively reduced, with a reduction frequency range of 7.1-15.6 GHz. Within this frequency range, an RCS reduction of over 10 dB is achieved, with a relative bandwidth of 74.9% for the 10 dB RCS. Compared to an equivalent-area metal ground plane, the maximum RCS reduction reaches 41.3 dB. The measured data and simulation results are basically consistent, indicating that this PCM structure effectively reduces antenna scattering.

[0035] In summary, this PCM-based low RCS circularly polarized broadband array antenna improves the antenna's circular polarization axial ratio bandwidth, maintains high gain, and ensures excellent circular polarization radiation performance, while increasing the RCS reduction bandwidth by 10dB, thus achieving effective RCS reduction.

[0036] The above description discloses only one preferred embodiment of the present invention, and should not be construed as limiting the scope of the present invention. Those skilled in the art will understand that all or part of the processes of the above embodiments can be implemented, and equivalent changes made in accordance with the claims of the present invention are still 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 elements, which are arranged in a grid pattern. Each antenna element has a five-layer structure, consisting of a metal patch, an upper dielectric substrate, a metal ground plane, a lower dielectric substrate, and a feed microstrip line from top to bottom. The metal patch, upper dielectric substrate, and metal ground plane constitute a PCM unit, which is arranged in a 6×6 checkerboard array. The feed network formed by the feed microstrip line consists of three Wilkinson power dividers with a 1-to-2 splitter configuration. The isolation resistance between the feed microstrip lines is R=100Ω. The pattern on the upper metasurface of each PCM unit is obtained by cutting out square patches at the upper left and lower right corners. It consists of three parts: two triangular metal patches at the upper left and lower right corners and a hexagonal metal patch in the middle. The PCM units on two adjacent antenna units are arranged in a mirror symmetric manner. The metal ground plane of the antenna element is slotted in the middle. The amplitudes of the slots of adjacent antenna elements in the array are the same, and the phase distributions are 0°, 90°, 180°, and 270°, respectively.

2. The low RCS circularly polarized broadband array antenna based on PCM as described in claim 1, characterized in that, Both the upper and lower dielectric substrates are made of F4B, but their thicknesses differ.

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