An ultrathin broadband RCS-reduced coding electromagnetic metasurface

Abstract

The present invention discloses an ultra-thin, broadband coded RCS reduction metasurface, which relates to the technical field of artificial electromagnetic metamaterials. The metasurface is composed of two metasurface units with the same reflection amplitude and a reflection phase difference of 180°, arranged according to an optimization rule obtained by a Particle Swarm Optimization (PSO) algorithm. Based on array theory, the present invention considers the design of two AMC structures for compounding, thereby effectively widening the RCS reduction bandwidth. Based on the principle of phase cancellation, and using a particle swarm optimization (PSO) algorithm, an ultra-thin, ultra-broadband coded RCS reduction metasurface is optimized and designed. The phase difference between the two metasurface basic units reaches 180°±1° over the full effective bandwidth (21-35GHz), resulting in the coded electromagnetic metasurface achieving excellent performance with a relative bandwidth of 47.2% and a reduction effect exceeding 10dB.

Description

Technical Field

[0001] The present invention relates to the technical field of artificial electromagnetic metamaterials, and in particular to an ultra-thin broadband RCS reduction coding electromagnetic metasurface. Background Art

[0002] In modern warfare, stealth technology is a crucial component, significantly impacting the survivability and combat capabilities of various weaponry. Antennas are a crucial component of various combat platforms, inherently possessing strong scattering properties within target systems. Therefore, effectively controlling and reducing the antenna's radar cross section (RCS) is crucial for designing low-observable radar systems.

[0003] New artificial electromagnetic materials (metamaterials) are artificial composite materials / structures with subwavelength periodic arrangements and widely adjustable electromagnetic properties. Through metamaterials, people can achieve the regulation of equivalent dielectric constant and magnetic permeability from "double positive" to "double negative", and thus realize a variety of anomalous effects such as negative refractive index, inverse Doppler effect, and perfect transmission. In recent years, researchers have made great progress in the mechanism research and practical application of metamaterials. In many applications, new artificial electromagnetic surfaces can replace artificial electromagnetic materials to achieve the same electromagnetic wave control function. Moreover, compared with new artificial electromagnetic materials, the thickness of new artificial electromagnetic surfaces is much smaller than the working wavelength, the structure is simple, easy to manufacture, and the loss is relatively lower.

[0004] The concept of coded metasurfaces has recently gained attention. Unlike traditional metamaterials, the phase response of their units corresponds to the digital bits "0" and "1." By designing an array with units in opposite phases, reflections of normal incident waves can be eliminated, achieving RCS reduction. While some artificial electromagnetic conductors (AMCs) have been reported for RCS reduction in the microwave band, their narrow bandwidth has severely limited their application.

[0005] Therefore, it is an urgent problem for those skilled in the art to propose an ultra-thin broadband RCS reduction coding electromagnetic metasurface to solve the problems existing in the prior art. Summary of the Invention

[0006] In view of this, the present invention provides an ultra-thin broadband RCS reduction coded electromagnetic metasurface. Based on array theory, two AMC structures are designed for compounding, thereby effectively broadening the bandwidth of the RCS reduction effect. According to the phase cancellation principle, the particle swarm optimization algorithm (PSO) is used to optimize the design to obtain an ultra-thin and ultra-broadband coded RCS reduction metasurface.

[0007] In order to achieve the above object, the present invention adopts the following technical solutions:

[0008] An ultra-thin broadband coded RCS reduction metasurface is composed of two metasurface units with the same reflection amplitude and a reflection phase difference of 180°, which are arranged according to the optimization rule obtained by the PSO algorithm.

[0009] Optionally, the metasurface unit structure includes a bottom metal layer, an intermediate dielectric layer and a top graphic unit arranged in sequence.

[0010] Optionally, the types of metasurface units include: a first metasurface unit representing 1 and a second metasurface unit representing 0.

[0011] Optionally, the graphic of the top-level graphic unit of the first metasurface unit includes a plurality of concentric quarter-circle rings and a transmission line, wherein the transmission line passes through the concentric quarter-circle rings and coincides with the diagonal of the intermediate dielectric layer; the second metasurface unit is obtained by rotating the first metasurface unit 90° along the center of symmetry.

[0012] Optionally, the reflection phase of the first metasurface unit is 90°, and the reflection phase of the second metasurface unit is 0°, wherein the reflection phase of the second metasurface unit is used as a reference phase.

[0013] Optionally, the graphic of the top-level graphic unit of the first supersurface unit consists of a first radius quarter-circle ring structure, a second radius quarter-circle ring structure, a third radius quarter-circle ring structure and a transmission line patch structure, and the center of the graphic of the top-level graphic unit coincides with the unit center.

[0014] Optionally, the top-layer graphic unit is made of copper.

[0015] Through the above technical solution, it can be seen that compared with the prior art, the present invention provides an ultra-thin broadband coded RCS reduction metasurface: based on array theory, two AMC structures are designed for compounding, thereby effectively broadening the RCS reduction effect bandwidth; according to the phase cancellation principle, and using the particle swarm (PSO) optimization algorithm, an ultra-thin and ultra-wideband coded RCS reduction metasurface is obtained for optimization design; the phase difference between the two metasurface basic units reaches 180°±1° in the full effective bandwidth (21-35GHz), so that the coded electromagnetic metasurface achieves excellent performance with a relative bandwidth of 47.2% and a reduction effect of more than 10dB. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are merely embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on the provided drawings without paying any creative work.

[0017] Figure 1 Schematic diagram of the metasurface unit structure proposed in the present invention, wherein 1.1 is a schematic diagram of the first metasurface unit structure, and 1.2 is a schematic diagram of the second metasurface unit structure;

[0018] Figure 2 Schematic diagram of the overall structure of the broadband RCS reduction coding metasurface optimized based on the PSO algorithm of the present invention;

[0019] Figure 3 Schematic diagram of the unit structure size of the metasurface of the present invention, wherein 3.1 is a schematic diagram of the size of the front view, and 3.2 is a schematic diagram of the size of the top view;

[0020] Figure 4 To reduce the phase difference between different units of the metasurface for the RCS of the present invention;

[0021] Figure 5 The polarization conversion rate of the unit of the RCS reduction metasurface of the present invention within the operating frequency band;

[0022] Figure 6 This is the RCS reduction rate diagram of the RCS reduction metasurface of the present invention. DETAILED DESCRIPTION

[0023] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0024] Reference Figure 2 As shown, the present invention discloses an ultra-thin broadband coded RCS reduction metasurface, which is composed of two metasurface units with the same reflection amplitude and a reflection phase difference of 180° arranged according to the optimization rule obtained by the PSO algorithm.

[0025] Furthermore, the metasurface unit structure includes a bottom metal layer, an intermediate dielectric layer and a top graphic unit arranged in sequence.

[0026] For further information, see Figure 1 As shown, the types of super surface units include: a first super surface unit representing 1 and a second super surface unit representing 0.

[0027] Furthermore, the graphic of the top-layer graphic unit of the first metasurface unit includes multiple concentric quarter-circle rings and a transmission line, wherein the transmission line passes through the concentric quarter-circle rings and coincides with the diagonal of the intermediate dielectric layer; the second metasurface unit is obtained by rotating the first metasurface unit 90° along the center of symmetry.

[0028] Furthermore, the reflection phase of the first metasurface unit is 90°, and the reflection phase of the second metasurface unit is 0°, wherein the reflection phase of the second metasurface unit is used as a reference phase.

[0029] For further information, see Figure 3 As shown, the graphic of the top-level graphic unit of the first metasurface unit consists of a first radius quarter-circle ring structure, a second radius quarter-circle ring structure, a third radius quarter-circle ring structure and a transmission line patch structure, and the center of the graphic of the top-level graphic unit coincides with the unit center.

[0030] Furthermore, the material of the top-level graphic unit is copper.

[0031] In one embodiment, a first metasurface unit of the metasurface unit is composed of a bottom metal plate, a middle dielectric layer, and a top-layer graphic unit, arranged according to an arrangement optimized by a PSO algorithm. A second metasurface unit of the metasurface unit is composed of a bottom metal plate, a middle dielectric layer, and a top-layer graphic unit.

[0032] The top layer of the first metasurface unit is composed of several concentric quarter-circle rings and a transmission line. The second metasurface unit is formed by rotating the basic unit 1 90 degrees along its center of symmetry. Their geometric parameters are: the concentric ring radii r1 = 0.65-0.75mm, r2 = 0.85-0.95mm, r3 = 1.15-1.25, r4 = 1.35-1.45mm, r5 = 1.55-1.65mm, r6 = 1.75-1.85mm, and the transmission line width w = 0.4-0.6mm, with a thickness t = 0.035mm. All are made of copper.

[0033] According to the design principle of RCS-reducing metasurface structures, the reflection amplitudes of the first and second metasurface units are the same, and the reflection phase difference should be 180° to minimize the RCS. However, in practical applications, an RCS reduction requirement of more than 10 dB is sufficient to consider the metasurface meeting the design requirements. Therefore, the phase difference between the first and second metasurface units should be at least 180°±37°.

[0034] In this embodiment, see Figure 3 .1 and Figure 3As shown in .2, the basic unit side length p = 4mm, the material used for the base plate and artificial surface electromagnetic structure is copper, with a conductivity of 2.65×107S / m and a thickness of t = 0.035mm. The intermediate layer medium is F4B, with a medium thickness of d = 1.5mm and a relative dielectric constant ε r =2.65, tangent loss tanδ = 0.001. The top graphic unit is located at the center of the dielectric surface and consists of several concentric quarter-circular rings and transmission lines. The radii of the concentric rings are r1 = 0.65-0.75mm, r2 = 0.85-0.95mm, r3 = 1.15-1.25, r4 = 1.35-1.45mm, r5 = 1.55-1.65mm, and r6 = 1.75-1.85mm. The transmission line width is w = 0.4-0.6mm, the thickness is t = 0.035mm, and the material is copper. Among them, the second-longest radius quarter-circle ring with radius r3 and r4 and the long radius quarter-circle ring with radius r5 and r6 are in the first and third quadrants, and the two are completely symmetrical along the counterclockwise 45° line; the short radius quarter-circle ring with radius r1 and r2 is in the second and fourth quadrants, and the two are completely symmetrical along the clockwise 45° line; the transmission line is a rectangle with a length of r6 and a width of w, arranged along the clockwise 45° line.

[0035] In order to achieve a better scattering effect, the same basic unit (0 or 1) is composed of 3×3 super 0 and 1 units. Because the two basic units meet the phase difference requirements, the super unit composed of the basic units also meets the phase difference requirements. The formed super units are arranged in a certain order to form a 6×6 array. The specific arrangement is: (0 and 1 represent the second metasurface unit and the second metasurface unit respectively) The first row is arranged according to "110000", the second row is arranged according to "101000", the third row is arranged according to "001000", the fourth row is arranged according to "101101", the fifth row is arranged according to "101010" and the sixth row is arranged according to "010111". Finally, the size of the entire metasurface structure is 72mm×72mm.

[0036] Since the pattern designs of the present invention are all centrosymmetric and located at the center of the entire structure, the present invention is not sensitive to x-polarized and y-polarized incident waves. The present invention forms a metasurface array by encoding and optimizing a specific pattern design using the PSO algorithm and arranging it in a specific manner, which can achieve a better RCS reduction effect. Figure 4-6 As shown in the figure, according to the results of CST full-wave simulation, compared with metal plates of the same size, the present invention basically meets the 10dB reduction requirement in the 12-14GHz frequency band, and fully meets the 10dB reduction requirement in the 21-35GHz frequency band. At a frequency of 24.5GHz, it can achieve an RCS reduction peak of 17.5dB.

[0037] The above description of the disclosed embodiments is presented in an incremental manner to enable one skilled in the art to implement or use the present invention. Various modifications to these embodiments will be readily apparent to one skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention is not limited to the embodiments shown herein but is to be construed in the widest possible manner consistent with the principles and novel features disclosed herein.

Claims

1. An ultra-thin broadband coded RCS reduction metasurface, characterized by: It is composed of two metasurface units with the same reflection amplitude and a reflection phase difference of 180°, arranged according to the optimization rule obtained by the PSO algorithm; The structure of the metasurface unit includes a bottom metal layer, an intermediate dielectric layer and a top graphic unit arranged in sequence; The metasurface units include two types: a first metasurface unit representing 1 and a second metasurface unit representing 0; The pattern of the top-layer pattern unit of the first metasurface unit consists of a first-radius quarter-circle ring structure, a second-radius quarter-circle ring structure, a third-radius quarter-circle ring structure, and a transmission line patch structure, and the center of the pattern of the top-layer pattern unit coincides with the unit center; The radius of the first radius quarter-circle structure is greater than the radius of the second radius quarter-circle structure and greater than the radius of the third radius quarter-circle structure, and the first radius quarter-circle structure, the second radius quarter-circle structure and the third radius quarter-circle structure are concentric quarter-circle structures; The pattern of the top-layer pattern unit of the first metasurface unit includes two quarter-circle ring structures of the first radius symmetrically distributed along the diagonal line, two quarter-circle ring structures of the second radius symmetrically distributed along the diagonal line, two quarter-circle ring structures of the third radius and a transmission line; wherein the transmission line runs through the two quarter-circle ring structures of the first radius and the two quarter-circle ring structures of the second radius, and the two quarter-circle ring structures of the third radius are symmetrically distributed along the transmission line; The second metasurface unit is obtained by rotating the first metasurface unit 90° along the center of symmetry.

2. The ultra-thin broadband coded RCS reduction metasurface according to claim 1, characterized in that: The reflection phase of the first metasurface unit is 90°, and the reflection phase of the second metasurface unit is 0°, wherein the reflection phase of the second metasurface unit is used as a reference phase.

3. The ultra-thin broadband coded RCS reduction metasurface according to any one of claims 1-2, characterized in that: The material of the top-layer graphic unit is copper.

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