A low-radar cross-section (RCS) circularly polarized slot array antenna of a metasurface

Abstract

This invention discloses a low RCS circularly polarized slot array antenna with a metasurface, comprising an upper dielectric substrate and a lower dielectric substrate. The upper dielectric substrate has a polarization conversion metasurface printed on its upper surface, and a metal ground plane is printed on the upper surface of the lower dielectric substrate. A feeding structure is printed on the lower surface of the lower dielectric substrate. The polarization conversion metasurface is composed of passive resonant polarization conversion elements arranged in an N×N checkerboard pattern, where N≥6. The metal ground plane is etched with a checkerboard-patterned slot array antenna. This invention achieves a reduction in antenna RCS while simultaneously broadening the operating frequency band of the metasurface and improving the polarization conversion efficiency.

Description

Technical Field

[0001] This invention relates to the field of antenna technology, and in particular to a metasurface low RCS circularly polarized slot array antenna. Background Technology

[0002] With the development of military electronics technology, reducing radar cross section (RCS) has attracted widespread research interest. Currently, many methods have been proposed for reducing RCS in low-profile antennas. One common method is to reshape the antenna surface to deflect electromagnetic energy in a specific direction and to load radar-absorbing materials to convert incident electromagnetic wave energy into heat. Another method for antenna RCS control is to modify the antenna's scattering characteristics by loading electromagnetic metamaterial structures onto the antenna floor or radiating elements. By loading electromagnetic metamaterials, the phase, polarization, and propagation mode of electromagnetic waves can be freely controlled, achieving low RCS scattering of the antenna.

[0003] Electromagnetic metasurfaces are a typical type of two-dimensional artificial electromagnetic material. They are planar structures with unique electromagnetic properties formed by periodically arranging metasurface units with dimensions much smaller than the operating wavelength. For example, Grady et al. demonstrated that metamaterials used for linear polarization conversion are suitable for terahertz applications. The challenges of in-band RCS reduction, as well as RCS reduction over a wider bandwidth, remain hot research topics. Meanwhile, civilian and military equipment are constantly demanding higher radiation performance from antennas. How to effectively reduce the antenna RCS while ensuring normal antenna radiation, and even further improve the antenna's bandwidth, gain, and other radiation characteristics, is a current challenge. Summary of the Invention

[0004] To address the aforementioned issues, this invention provides a low RCS circularly polarized slot array antenna with a metasurface. It employs a multi-resonant structure to combine multiple effective frequency bands, broadening the operating frequency band of the metasurface and improving the polarization conversion rate (PCR). The designed polarization conversion metasurface is loaded as a cladding layer onto the circularly polarized slot array antenna, and a sequentially rotating feed network ensures antenna radiation performance while achieving a wideband RCS reduction of over 10 dB.

[0005] This invention provides a metasurface low RCS circularly polarized slot array antenna, the specific technical solution of which is as follows:

[0006] The antenna consists of an upper dielectric substrate and a lower dielectric substrate;

[0007] The upper dielectric substrate has a polarization conversion metasurface printed on its upper surface, the lower dielectric substrate has a metal ground plane printed on its upper surface, and the lower dielectric substrate has a power feeding structure printed on its lower surface.

[0008] The polarization conversion metasurface is composed of passive resonant polarization conversion units arranged in an N×N checkerboard pattern.

[0009] The metal floor is etched with a checkerboard-patterned slot array antenna.

[0010] Where N≥6.

[0011] By employing polarization-conversion metasurfaces distributed clockwise around the center, and utilizing the antiphase properties between adjacent metasurfaces, scattered energy can be reflected to the non-threatening angular domain direction, thus achieving effective RCS reduction.

[0012] Furthermore, the slot array antenna is composed of M×M strip slots, and adjacent slot antennas are distributed in a clockwise rotation around the center.

[0013] Where M≥2.

[0014] The array antenna uses slot antennas distributed in a clockwise rotation around the center to achieve circular polarization radiation.

[0015] Furthermore, the length and width of the strip-shaped gap are the same.

[0016] Furthermore, in the antenna feeding structure using a rectangular microstrip line, the rectangular microstrip line is perpendicular to the strip slot.

[0017] The rectangular microstrip line, as the antenna's feeding structure, can effectively couple the energy fed in through the coaxial line located below the microstrip line into the slot array antenna, thereby achieving effective antenna radiation.

[0018] The coaxial line is the excitation source when the antenna is fed, that is, the end of the feeding structure.

[0019] Furthermore, the polarization conversion metasurface consists of a first circularly chamfered square patch placed in the middle, two second circularly chamfered square patches symmetrically distributed along the diagonal, two square patches located at the vertices, and a strip patch;

[0020] The square vertices of the first circularly chamfered square patch and the second circularly chamfered square patch are connected end to end from the inside out. The two strip-type patches are placed along the diagonal, with one end placed at the overlap of the first circularly chamfered square patch, and the other end of each patch is connected to a square patch.

[0021] By combining multiple effective frequency bands through a multi-resonant structure, the operating frequency band of the metasurface is extended and the polarization conversion efficiency (PCR) is improved.

[0022] Furthermore, the first circularly chamfered square patch has a side length of 2.54 mm and a chamfer radius of 1 mm;

[0023] The second circularly chamfered square patch has a length of 0.94 mm and a chamfer radius of 0.62 mm.

[0024] Furthermore, the square patch has a side length of 0.66 mm.

[0025] Furthermore, the strip patch has a width of 0.1 mm and a length of 1.8 mm.

[0026] Furthermore, the upper dielectric substrate is a rectangular plate with a dielectric constant of 2.2, and a 19.3mm × 2.6mm × 2.5mm gap is formed on the upper dielectric substrate.

[0027] Furthermore, the lower dielectric substrate is a substrate with a dielectric constant of 2.65.

[0028] The beneficial effects of this invention are as follows:

[0029] 1. The polarization conversion metasurface unit in this invention adopts an integrated design structure of strip patch and multi-circular chamfered square patch to achieve polarization conversion effect in a wide frequency band.

[0030] 2. This invention uses a checkerboard-patterned arrangement of polarization conversion metasurfaces as the cladding for an array antenna. The array antenna will generate two reflected electromagnetic waves with equal cross-polarization amplitudes and a 180° phase difference. This will cause the energy of the incident electromagnetic wave in the axial direction to be scattered to the four diagonals of free space, thereby achieving a reduction in the radar cross section of the antenna over a wide frequency band. Attached Figure Description

[0031] Figure 1 This is a schematic diagram of the overall antenna structure of the present invention;

[0032] Figure 2 This is a schematic diagram of the polarization conversion unit structure of the present invention;

[0033] Figure 3 This is a schematic diagram of the polarization conversion rate (PCR) simulation results of the polarization conversion metasurface of the present invention;

[0034] Figure 4 This is a schematic diagram comparing the reflection coefficient amplitude of the slot array antenna with the loaded polarization conversion metasurface of the present invention;

[0035] Figure 5 This is a schematic diagram comparing the axial ratios of the slot array antenna with the unloaded polarization conversion metasurface of the present invention;

[0036] Figure 6This is a schematic diagram comparing the xoz plane of the antenna radiation direction of the slot array antenna and the reference antenna at 11.3 GHz.

[0037] Figure 7 This is a schematic diagram comparing the yoz plane of the antenna radiation direction of the slot array antenna and the reference antenna at 11.3 GHz.

[0038] Figure 8 This is a schematic diagram of the monostatic RCS simulation results of the slot array antenna and reference antenna of the present invention under vertical incidence of electromagnetic waves with different polarizations.

[0039] Figure labeling: 1-Upper dielectric substrate, 2-Polarization conversion metasurface, 3-Metal ground plane, 4-Lower dielectric substrate, 5-Feed network, 21-First circular chamfered square patch, 22-Second circular chamfered square patch, 23-Square patch, 24-Strip patch. Detailed Implementation

[0040] The technical solutions in the embodiments of the present invention are clearly and completely described in the following description. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0041] In the description of the embodiments of the present invention, it should be noted that the indicated orientation or positional relationship is based on the orientation or positional relationship shown in the accompanying drawings, or the orientation or positional relationship in which the product of the invention is conventionally placed during use, or the orientation or positional relationship in which those skilled in the art conventionally understand it during use. This is only for the convenience of describing the present invention and simplifying the description, and is 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, it should not be construed as a limitation of the present invention. Furthermore, the terms "first" and "second" are only used to distinguish descriptions and should not be construed as indicating or implying relative importance.

[0042] In the description of the embodiments of the present invention, it should also be noted that, unless otherwise explicitly specified and limited, the terms "set" and "connection" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a direct connection or an indirect connection through an intermediate medium. Those skilled in the art can understand the specific meaning of the above terms in the present invention based on the specific circumstances.

[0043] Example 1

[0044] Embodiment 1 of the present invention discloses a metasurface low RCS circularly polarized slot array antenna, such as Figure 1 As shown, the specific structure is as follows:

[0045] Includes upper dielectric substrate 1 and lower dielectric substrate 4;

[0046] The upper dielectric substrate 1 has a polarization conversion metasurface 2 printed on its upper surface, the lower dielectric substrate 4 has a metal ground plane 3 printed on its upper surface, and the lower dielectric substrate 4 has a power feeding structure printed on its lower surface.

[0047] In this embodiment, the upper dielectric plate 1 is a rectangular plate with a dielectric constant of 2.2, and a 19.3mm×2.6mm×2.5mm gap is opened on the upper dielectric plate 1;

[0048] In this embodiment, the lower dielectric substrate 4 is a substrate with a dielectric constant of 2.65.

[0049] The polarization conversion metasurface 2 is composed of passive resonant polarization conversion units arranged in an N×N checkerboard pattern.

[0050] Where N≥6, M≥2.

[0051] By employing a polarization conversion metasurface 2 distributed clockwise around the center, the scattered energy can be reflected to the non-threatening angular domain direction by utilizing the antiphase properties between adjacent metasurfaces, thus achieving effective RCS reduction.

[0052] like Figure 2 As shown, in this embodiment, the polarization conversion metasurface 2 consists of a first circularly chamfered square patch 21 placed in the middle, two second circularly chamfered square patches 22 symmetrically distributed along the diagonal, two square patches 23 located at the vertices, and a strip patch 24.

[0053] The square vertices of the first circularly chamfered square patch 21 and the second circularly chamfered square patch 22 are connected end to end from the inside out. The two strip-type patches 24 are placed along the diagonal, with one end placed at the overlapping part of the first circularly chamfered square patch 21, and the other end of each patch is connected to a square patch 23.

[0054] The overlapping area refers to the intersection of the first circularly chamfered square patch 21 and the second circularly chamfered square patch 22.

[0055] By combining multiple effective frequency bands through a multi-resonant structure, the operating frequency band of the metasurface is extended and the polarization conversion efficiency (PCR) is improved.

[0056] Specifically, the first circularly chamfered square patch 21 has a side length of 2.54 mm and a chamfer radius of 1 mm;

[0057] The second circular chamfered square patch 22 has a length of 0.94 mm and a chamfer radius of 0.62 mm.

[0058] The square patch 23 has a side length of 0.66 mm.

[0059] The strip patch 24 has a width of 0.1 mm and a length of 1.8 mm.

[0060] The metal floor 3 is etched with M×M slot array antennas arranged in a checkerboard pattern.

[0061] Specifically, in this embodiment, the metal floor 3 is etched with a slot array antenna consisting of 2×2 strip slots, forming a checkerboard arrangement, and adjacent slot antennas are distributed in a clockwise rotation around the center.

[0062] The array antenna uses slot antennas distributed in a clockwise rotation around the center to achieve circular polarization radiation.

[0063] In this embodiment, the strip-shaped gap has the same length and width, and the rectangular microstrip line is perpendicular to the strip-shaped gap;

[0064] Using the rectangular microstrip line as the antenna feed structure can effectively couple the energy fed through the coaxial line located below the microstrip line into the slot array antenna, thereby achieving effective antenna radiation.

[0065] Based on the above antenna structure, the simulation results are as follows; Figure 3 As shown, the simulation results of the polarization conversion efficiency (PCR) of the polarization conversion metasurface 2 (PCM) are presented. It can be seen that the polarization conversion efficiency (PCR) of the polarization conversion metasurface 2 in this embodiment is greater than 90% in the wide frequency band of 9.8GHz-30.4GHz, indicating that the polarization conversion metasurface 2 described in this embodiment has a high-efficiency polarization conversion capability in a wide frequency band. The use of a multi-resonant structure can achieve broadband and high-efficiency characteristics.

[0066] like Figure 4 and Figure 5 The figure shows the simulation results of the reflection coefficient and axial ratio of the invented antenna and the reference antenna under radiation conditions. From... Figure 4 It can be seen that the reference antenna's -10dB impedance bandwidth is 10.64-12.11GHz, with a relative bandwidth of 12.9%. The designed antenna's impedance bandwidth (10.4-12.3GHz, 16.7%) is 3.8% higher than the reference antenna's bandwidth. Figure 5 As can be seen, the axial ratio of the reference antenna remains below 3dB from 10.7GHz to 11.43GHz. Compared to the design antenna with a polarization conversion surface, the axial ratio relative bandwidth (10.98-11.68GHz, 6.2%) remains almost unchanged, but the frequency point is slightly shifted.

[0067] like Figure 6and Figure 7 The figure shows the simulation results of the radiation patterns of the antenna of the present invention and the reference antenna at 11.3 GHz. It can be seen that the antenna of the present invention and the reference antenna have good radiation patterns in the xoz and yoz planes, and can achieve circular polarization in the X-band.

[0068] like Figure 8 The figure shows the simulation results of the monostatic radar cross section (RCS) of the antenna of this invention and the reference antenna under incident wave illumination with two polarizations. It can be seen that, compared with the reference antenna in this embodiment, the antenna of this invention can achieve a monostatic RCS reduction of more than 10 dB from 10.1 GHz to 30.5 GHz, and can achieve both in-band and out-of-band RCS. Under different polarizations, the maximum reduction in monostatic RCS at a frequency of 11 GHz is 28 dB.

[0069] This invention is not limited to the specific embodiments described above. The invention extends to any new feature or combination disclosed in this specification, as well as any new method or process step or combination disclosed herein.

Claims

1. A metasurface low RCS circularly polarized slot array antenna, characterized in that, Includes upper dielectric substrate and lower dielectric substrate; The upper dielectric substrate has a polarization conversion metasurface printed on its upper surface, the lower dielectric substrate has a metal ground plane printed on its upper surface, and the lower dielectric substrate has a power feeding structure printed on its lower surface. The polarization conversion metasurface is composed of passive resonant polarization conversion units arranged in an N×N checkerboard pattern. The metal floor is etched with a checkerboard-patterned slot array antenna. Where N≥6; The polarization conversion metasurface consists of a first circularly chamfered square patch placed in the middle, two second circularly chamfered square patches symmetrically distributed along the diagonal, two square patches located at the vertices, and a strip patch. The square vertices of the first circularly chamfered square patch and the second circularly chamfered square patch are connected end to end from the inside out. The two strip-type patches are placed along the diagonal, with one end placed at the overlap of the first circularly chamfered square patch, and the other end of each patch is connected to a square patch.

2. The low RCS circularly polarized slot array antenna with metasurface according to claim 1, characterized in that, The slot array antenna consists of M×M strip slots, and adjacent slot antennas are arranged in a clockwise rotation around the center. Where M≥2.

3. The low RCS circularly polarized slot array antenna with metasurface according to claim 2, characterized in that, The length and width of the strip-shaped slit are the same.

4. The low RCS circularly polarized slot array antenna with metasurface according to claim 3, characterized in that, The feeding structure uses a rectangular microstrip line as the antenna, wherein the rectangular microstrip line is perpendicular to the strip slot.

5. The low RCS circularly polarized slot array antenna with metasurface according to claim 1, characterized in that, The first circularly chamfered square patch has a side length of 2.54 mm and a chamfer radius of 1 mm. The second circularly chamfered square patch has a length of 0.94 mm and a chamfer radius of 0.62 mm.

6. The low RCS circularly polarized slot array antenna with metasurface according to claim 5, characterized in that, The square patch has a side length of 0.66 mm.

7. The low RCS circularly polarized slot array antenna with metasurface according to claim 6, characterized in that, The strip patch has a width of 0.1 mm and a length of 1.8 mm.

8. The low RCS circularly polarized slot array antenna with metasurface according to claim 1, characterized in that, The upper dielectric substrate is a rectangular plate with a dielectric constant of 2.2, and a 19.3mm × 2.6mm × 2.5mm gap is cut into the upper dielectric substrate.

9. The low RCS circularly polarized slot array antenna with metasurface according to claim 1, characterized in that, The lower dielectric substrate is a substrate with a dielectric constant of 2.65.

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