Rigid linear-circular dual-polarization conversion metasurface

Abstract

The invention belongs to the technical field of electromagnetic regulation and control, and particularly relates to a rigid linear-circular dual-polarization conversion metasurface. The rigid reflection type dual-polarization conversion metasurface structure is composed of a periodic array of anisotropic metasurfaces. A unit of the super-structure surface is composed of a metal double-circle chamfered square patch resonator and a metal grounding plate. And model simulation and structure optimization are carried out by adopting a CST microwave studio. A periodic boundary condition is adopted in x-axis and y-axis directions to simulate an infinite period array, an electrical boundary is adopted in a z-axis positive direction, and a wave vector direction is along a z-axis negative direction. The polarization conversion rate of the polarization conversion metasurface in the frequency band of 6.85-11.05 GHz reaches 90%, the corresponding relative bandwidth is 47.15%, and high-efficiency wide-incidence-angle linear polarization conversion is achieved. The axial ratio in the frequency bands of 5.83 GHz to 6.68 GHz and 11.54 GHz to 16.93 GHz is lower than 3 dB, the corresponding relative bandwidths are respectively 13.59% and 37.86%, and high-efficiency circular polarization conversion is realized. And good linear polarization conversion performance and circular polarization conversion performance can be obtained in a range that the incident angle is less than or equal to 50 degrees.

Description

Technical Field

[0001] This application belongs to the field of electromagnetic regulation technology, and particularly relates to a rigid wire-circle dual-polarization conversion metasurface. Background Art

[0002] Breakthrough results have been achieved in the research of reflective polarization conversion metasurfaces. However, most of the existing research is for single frequency bands with poor polarization conversion performance. In the research of dual-polarization conversion, most have good polarization conversion performance for one polarization while poor for the other, with a relatively narrow relative bandwidth, and lack of analysis of oblique incidence characteristics or strong dependence on the incident angle.

[0003] When the polarization direction of the incident electromagnetic wave is inconsistent with the designed polarization direction of the metasurface, its performance will deteriorate. In the actual application environment, it is necessary to detect the polarization direction of the incoming wave and automatically adjust the attitude of the metasurface so that the polarization direction of the incoming wave is consistent with the response direction of the metasurface, in order for the metasurface to exhibit good electromagnetic response. This undoubtedly increases the design and control difficulties and is not conducive to practical applications. Therefore, in many fields such as radar detection and satellite communication, dual-polarization or even multi-polarization metasurfaces will surely have a broader application prospect.

[0004] Therefore, it is necessary to design a rigid wire-circle dual-polarization conversion metasurface. Summary of the Invention

[0005] The purpose of this application is to provide a rigid wire-circle dual-polarization conversion metasurface, aiming to solve the problem that the existing rigid metasurfaces cannot achieve wire-circle dual conversion. The metasurface is composed as follows:

[0006] This rigid wire-circle dual-polarization conversion metasurface is composed of a periodic arrangement of anisotropic metasurface units.

[0007] The unit of this metasurface consists of a metal double-circle chamfered square patch resonator and a metal ground plane;

[0008] Periodic boundary conditions are used in the x-axis and y-axis directions to simulate an infinite periodic array, and an electric boundary is used in the positive z-axis direction, with the wave vector direction along the negative z-axis direction. Brief Description of the Drawings

[0009] Figure 1 Schematic top structure diagram of the metasurface unit provided by an embodiment of this application;

[0010] Figure 2 Schematic top-down structure diagram of the unit provided by an embodiment of this application;

[0011] Figure 3 Schematic bottom structure diagram of the unit provided by an embodiment of this application;

[0012] Figure 4The amplitude diagram of the reflection coefficient provided by an embodiment of the present application;

[0013] Figure 5 The schematic diagram of the metasurface structure composed of units provided by an embodiment of the present application;

[0014] Figure 6 The reflection coefficient provided by an embodiment of the present application;

[0015] Figure 7 The PCR value provided by an embodiment of the present application;

[0016] Figure 8 The AR value provided by an embodiment of the present application. Detailed implementation manners

[0017] In order to make the technical problems, technical solutions and beneficial effects to be solved by the present application clearer, the present application will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present application and are not used to limit the present application.

[0018] As Figure 1 shown, the rigid wire circular dual-polarization conversion metasurface is composed of a periodic arrangement of units of the anisotropic metasurface.

[0019] The unit of the metasurface consists of a metal double-round-corner square patch resonator and a metal ground plane separated by an FR-4 dielectric substrate (ε r = 2 - 0.025j) with a thickness h of 2.4 mm. The double-round-corner square patch is symmetric about the top-layer diagonal. The top layer and the bottom layer are made of copper films with a conductivity of 5.8×107 S / m and a thickness t of 0.035 mm.

[0020] The corner radius m of the metal double-round-corner square patch resonator is 3 mm;

[0021] The length l of the metal double-round-corner square patch resonator is 6 mm;

[0022] The width of the top-layer copper film is 7.00 mm.

[0023] For the periodic arrangement of the units of the metasurface, periodic boundary conditions are adopted in the x-axis and y-axis directions to simulate an infinite periodic array, and an electric boundary is adopted in the positive z-axis direction. The wave vector direction is along the negative z-axis direction.

[0024] As Figures 4 - 7 shown, the designed unit cell structure is symmetric about the top-layer diagonal, so it has the same polarization conversion effect on x-polarized incident waves and y-polarized incident waves. Figure 5It shows that co-polarization occurs at frequencies of 7.30 GHz and 10.01 GHz, and the magnitudes of the co-polarization reflection coefficients reach -26.26 dB and -32.05 dB respectively. At this time, the magnitude of the cross-polarization reflection coefficient is close to 0 dB. Therefore, at the resonant frequencies, the incident x-polarized wave and y-polarized wave can be mutually converted by the metasurface. The co-polarization and cross-polarization reflection coefficients are obtained by linearly processing the magnitudes of the co-polarization and cross-polarization reflection coefficients as Figure 6 shown. It can be seen from the figure that in the frequency band of 6.84 - 11.06 GHz, when the co-polarization reflection coefficient is lower than 0.3, the corresponding cross-polarization reflection coefficient is higher than 0.9, indicating that most of the incident waves undergo cross-polarization conversion. Figure 7 is the PCR when the x-polarized wave and y-polarized wave are incident vertically. It can be seen from the figure that in the frequency band of 6.84 - 11.06 GHz, the PCR is higher than 90%, and its relative bandwidth is 47.15%, enabling efficient linear polarization conversion. In addition, at the resonant frequencies of 7.30 GHz and 10.01 GHz, the PCR is close to 1, achieving perfect linear polarization conversion.

[0025] As Figure 8 shown, at frequencies of 6.31 GHz and 13.02 GHz, the reflection coefficients when the x-polarized wave is incident satisfy Rxx = Ryx, and at the same frequencies, the reflection coefficients when the y-polarized wave is incident also satisfy Ryy = Rxy. At this time, the corresponding ARs at both frequencies are close to 0 dB. This result indicates that the incident linearly polarized wave can be completely converted into a circularly polarized wave, achieving perfect linear-to-circular polarization conversion. In the frequency bands of 5.83 - 6.68 GHz and 11.54 - 16.93 GHz, the AR is lower than 3 dB, and the corresponding relative bandwidths are 13.59% and 37.86% respectively. The frequency band where the AR is less than 3 dB is the operating bandwidth of the circular polarization conversion.

[0026] The above embodiments are only used to illustrate the technical solutions of the present application, and are not intended to limit them; although the present application has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that they can still modify the technical solutions recorded in the foregoing embodiments, or perform equivalent replacements for some of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the spirit and scope of the technical solutions of the various embodiments of the present application, and should all be included in the protection scope of the present application.

Claims

1. A rigid wire circular dual-polarization conversion metasurface, characterized in that It is composed as follows: The rigid-line circularly polarized conversion metasurface is composed of a periodic arrangement of unit cells of the anisotropic metasurface; The unit of the metasurface consists of a metal double-rounded-corner square patch resonator and a metal ground plane separated by an FR-4 dielectric substrate with a thickness h of 2.4 mm (ε r = 2 - 0.025j). The double-rounded-corner square patch is symmetric about the top diagonal. The top layer and the bottom layer are made of copper thin films with a conductivity of 5.8×107 S / m and a thickness t of 0.035 mm; The chamfer radius m of the metal double circular chamfered square patch resonator is 3 mm; The length l of the metal double circular chamfered square patch resonator is 6 mm; The width of the top copper film is 7.00 mm; For the periodic arrangement of unit cells of the metasurface, periodic boundary conditions are used in the x-axis and y-axis directions to simulate an infinite periodic array, an electric boundary is used in the positive z-axis direction, and the wave vector direction is along the negative z-axis direction.

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