A wide-angle stealth absorbing metasurface

Abstract

This invention discloses a wide-angle stealth absorbing metasurface, which is composed of N×N absorbing units. Each absorbing unit structure includes an anti-reflection layer, an air layer, and a ring-shaped absorbing layer. The absorbing unit structure, from top to bottom, consists of a first metal layer (1), a first dielectric layer (2), a second dielectric layer (3), a second metal layer (4), a third dielectric layer (5), and a third metal layer (6). By loading the anti-reflection metasurface unit and appropriately adjusting the thickness of the air layer, it can be cascaded with traditional absorbing units. The absorbing metasurface unit and its design method of this invention improve the absorption rate of the unit under large-angle oblique incidence conditions, simplify the absorber design process, avoid the design requirements of complex unit structures, and reduce the complexity of structural design when dealing with large-angle incidence.

Description

Technical Field

[0001] This invention relates to the field of metamaterial absorbing technology, and in particular to metasurface absorbing structures with a wide incident angle range, belonging to the fields of communication, radar and novel artificial electromagnetic materials. Background Technology

[0002] Metamaterials, as an emerging type of wave-absorbing material, allow for more flexible electromagnetic parameter design by freely adjusting the effective dielectric constant and magnetic permeability of the medium to control the propagation direction of electromagnetic waves. This enables wider bandwidth, thinner and lighter volume, and stronger absorption and stealth effects.

[0003] As the incident angle of the incident wave increases, under different polarization conditions, the characteristic impedance of free space and the input impedance of the absorbing structure exhibit different trends, causing the absorption efficiency of the absorber to drop sharply under large-angle oblique incidence. Using special materials such as graphene to reduce the sensitivity of the unit cell to the incident angle, or designing more complex unit cell structures to achieve wide-angle absorption, can achieve stable oblique incidence performance within a 60° range. However, once the incident angle exceeds 60°, the absorption efficiency of the unit cell still decreases significantly. Summary of the Invention

[0004] Technical problem: The purpose of this invention is to provide a wide-angle stealth absorbing metasurface to improve the absorption performance of the absorbing unit under large-angle oblique incidence conditions, simplify the design process of metamaterial absorbers, and realize wide-angle stealth absorption.

[0005] Technical solution: The wide-angle stealth absorbing metasurface of the present invention is composed of N×N absorbing units. Each absorbing unit includes an anti-reflection layer, an air layer, and an absorbing layer. The structure of the absorbing unit from top to bottom is a first metal layer, a first dielectric layer, a second dielectric layer, a second metal layer, a third dielectric layer, and a third metal layer. The first metal layer and the first dielectric layer constitute the unit anti-reflection layer. The second dielectric layer is an air layer. The second metal layer, the third dielectric layer, and the third metal layer constitute a ring-shaped absorbing unit.

[0006] The first metal layer includes a large metal frame and four smaller metal frames located at the four right angles of the large metal frame, with two branches in each smaller metal frame.

[0007] The two branches in the small metal frame are located at opposite corners of the small metal frame and are on opposite corners of the large metal frame. The branches are 2.6 mm long and 0.2 mm wide.

[0008] The side length of the large metal frame is equal to the period of the absorbing unit, and the width is 0.1 mm; the thickness is 0.035 mm.

[0009] The small metal frame has a side length of 5.4 mm, a width of 0.2 mm, and a thickness of 0.035 mm.

[0010] The first and third dielectric layers are FR4 glass fiber epoxy resin substrates with a relative permittivity of 4.3 and a loss tangent of 0.025.

[0011] The dielectric structure of the first dielectric layer and the third dielectric layer is square, the thickness of the first dielectric layer is 2 mm, and the thickness of the third dielectric layer is 1.6 mm.

[0012] The second metal layer is an annular metal patch with an inner diameter of 7.8 mm, an outer diameter of 9.8 mm, and a thickness of 0.035 mm.

[0013] The third metal layer has the same shape and size as the third dielectric layer, and the thickness of the third metal layer is 0.035 mm.

[0014] The second dielectric layer is an air layer with a thickness of 45 mm, which is used to cascade the antireflection layer and the microwave absorbing layer.

[0015] Beneficial effects: Compared with the prior art, the technical solution of the present invention has the following advantages:

[0016] This invention improves the absorption performance of microwave absorbing units under large-angle oblique incidence conditions by loading an antireflection metasurface layer on top of a traditional microwave absorbing unit structure. Microwave absorbers typically experience a significant decrease in absorption performance with increasing incident angle, and achieving wide-angle absorption using special materials or more complex unit structures remains challenging. In contrast, this invention enhances oblique incidence absorption performance and stabilizes the absorption frequency by adding an antireflection layer to a traditional microwave absorbing structure, thereby avoiding complex unit designs and simplifying the design process. Attached Figure Description

[0017] Figure 1 This is a schematic diagram of the wide-angle domain absorbing metasurface unit structure of the present invention;

[0018] Figure 2a The TE polarization absorption rate curve of a traditional single-layer ring absorbing unit;

[0019] Figure 2b A graph showing the TE polarization absorption rate of a wide-angle absorbing metasurface unit.

[0020] Figure 3a The graph shows the polarization absorption rate of a traditional single-layer ring absorbing unit (TM).

[0021] Figure 3b This is a graph showing the polarization absorption rate of the wide-angle absorbing metasurface unit TM.

[0022] The diagram includes: first metal layer 1, first dielectric layer 2, second dielectric layer 3, second metal layer 4, third dielectric layer 5, third metal layer 6; large metal frame 11, small metal frame 12, and branch 13. Detailed Implementation

[0023] This invention proposes a novel wide-angle stealth absorbing metasurface design. By loading an anti-reflection structure on top of an existing absorber, separated by air, the absorption rate is improved under large-angle oblique incidence conditions. Compared with existing technologies, this invention simplifies the absorber design process, avoids the need for complex unit structure design, and reduces the complexity of structural design when dealing with large-angle incidence.

[0024] The present invention will be further described below with reference to the accompanying drawings and specific embodiments.

[0025] like Figure 1 As shown, this embodiment provides a novel wide-angle stealth absorbing metasurface, which consists of an anti-reflection layer, an air layer, and an annular absorbing layer from top to bottom.

[0026] The wide-angle absorbing metasurface unit structure of the present invention comprises three metal layers and three dielectric layers.

[0027] The layered structure of each basic unit, from top to bottom, includes:

[0028] The first layer is the first metal layer 1;

[0029] The second layer is the first dielectric layer 2;

[0030] The third layer is the second dielectric layer 3;

[0031] The fourth layer is the second metal layer 4

[0032] The fifth layer is the third dielectric layer 5;

[0033] The sixth layer is the third metal layer 6;

[0034] The first dielectric layer 2 and the third dielectric layer 5 are FR4 glass fiber epoxy resin substrates with a relative permittivity of 4.3 and a loss tangent of 0.025.

[0035] The dielectric structure of the first dielectric layer 2 and the third dielectric layer 5 is square. The thickness of the first dielectric layer 2 is 2 mm and the thickness of the third dielectric layer 5 is 1.6 mm.

[0036] The second metal layer 4 is an annular metal patch with an inner diameter of 7.8 mm, an outer diameter of 9.8 mm, and a thickness of 0.035 mm.

[0037] The third metal layer 6 has the same shape and size as the third dielectric layer 5, and the thickness of the third metal layer 6 is 0.035 mm.

[0038] The second dielectric layer 3 is an air layer with a thickness of 45 mm, which is used to cascade the anti-reflection layer and the microwave absorbing layer.

[0039] The first metal layer 1 includes a large metal frame 11 and four smaller metal frames 12 located at the four right angles of the large metal frame 11. Each smaller metal frame 12 has two branches 13. The two branches 13 in each smaller metal frame 12 are located at two opposite corners of the smaller metal frame 12, and are also located on two diagonals of the larger metal frame 11. The branches 13 have a length of 2.6 mm and a width of 0.2 mm.

[0040] The side length of the large metal frame 11 is equal to the unit period of 16mm, the width is 0.1mm, and the thickness is 0.035mm.

[0041] The small metal frame 12 has a side length of 5.4 mm, a width of 0.2 mm, and a thickness of 0.035 mm.

[0042] The traditional annular absorbing unit has the same periodic size as the antireflective layer unit, both being 16mm, to ensure easy arraying when several absorbing units are periodically arranged. The inner ring diameter of the annular metal patch is 7.8mm, the patch width is 2mm, and the thickness is 0.035mm.

[0043] like Figure 2a and Figure 2b As shown, when the incident wave is a TE-polarized wave, the metasurface absorbing unit of the present invention can still maintain a high absorptivity within a wide incident angle range of 0-85°. Specifically, the frequency band with an absorptivity greater than 85% is 5.78-5.83 GHz when the incident angle is 0-30°; the frequency band with an absorptivity greater than 85% is 5.75-5.84 GHz when the incident angle is 60-80°; and the frequency band with an absorptivity greater than 85% is 5.73-5.97 GHz when the incident angle is 85°. In particular, when the incident angle increases to 80° and 85°, the absorption peak values ​​increase from 76% and 51% to 98% and 95%, respectively, compared to the traditional single-layer ring absorber unit; and the bandwidths where the absorptivity of the metasurface absorbing unit of the present invention exceeds 90% are 5.71-5.91 GHz and 5.75-5.95 GHz, respectively, which also expands the absorption bandwidth compared to the traditional single-layer ring absorber unit.

[0044] like Figure 3a and Figure 3bAs shown, when the incident wave is a TM-polarized wave, the metasurface absorbing unit of the present invention exhibits good absorption frequency stability. Within the incident angle range of 0-60°, the absorption rate is improved compared to the traditional single-layer annular absorber unit, while within the incident angle range of 0-80°, the absorption frequency is more stable.

[0045] It should be further noted that the operating center frequency of the unit provided in this embodiment is 5.8 GHz. The overall operating frequency band is in the sub-6 GHz band. By adjusting the unit size, its operating frequency band can be flexibly adjusted while still achieving good multi-functional electromagnetic control performance.

[0046] The above description is merely a preferred embodiment of the present invention. It should be noted that those skilled in the art can make various improvements and optimizations without departing from the basic principles of the present invention. These improvements and optimizations should also be included within the scope of protection of the present invention.

Claims

1. A wide-angle stealth absorbing metasurface, characterized in that: The metasurface is composed of N×N absorbing units. Each absorbing unit includes an anti-reflection layer, an air layer, and an absorbing layer. The structure of the absorbing unit from top to bottom is as follows: first metal layer (1), first dielectric layer (2), second dielectric layer (3), second metal layer (4), third dielectric layer (5), and third metal layer (6). The first metal layer (1) and the first dielectric layer (2) form the unit anti-reflection layer; the second dielectric layer (3) is the air layer; the second metal layer (4), the third dielectric layer (5), and the third metal layer (6) form a ring-shaped absorbing unit. The first metal layer (1) includes a large metal frame (11) and four small metal frames (12) located at the four right angles of the large metal frame (11). Each small metal frame (12) has two branches (13) located at the two opposite corners of the small metal frame (12) respectively, and the two branches (13) are on the two diagonal lines of the large metal frame (11). The length of the branch (13) is 2.6 mm and the width is 0.2 mm.

2. The wide-angle stealth absorbing metasurface according to claim 1, characterized in that: The side length of the large metal frame (11) is equal to the period of the absorbing unit, the width is 0.1 mm, and the thickness is 0.035 mm.

3. The wide-angle stealth absorbing metasurface according to claim 1, characterized in that: The small metal frame (12) has a side length of 5.4 mm, a width of 0.2 mm, and a thickness of 0.035 mm.

4. The wide-angle stealth absorbing metasurface according to claim 1, characterized in that: The first dielectric layer (2) and the third dielectric layer (5) are FR4 glass fiber epoxy resin substrates with a relative permittivity of 4.3 and a loss tangent of 0.

025.

5. The wide-angle stealth absorbing metasurface according to claim 1, characterized in that: The dielectric structure of the first dielectric layer (2) and the third dielectric layer (5) is square. The thickness of the first dielectric layer (2) is 2 mm and the thickness of the third dielectric layer (5) is 1.6 mm.

6. The wide-angle stealth absorbing metasurface according to claim 1, characterized in that: The second metal layer (4) is an annular metal patch with an inner diameter of 7.8 mm, an outer diameter of 9.8 mm, and a thickness of 0.035 mm.

7. The wide-angle stealth absorbing metasurface according to claim 1, characterized in that: The third metal layer (6) has the same shape and size as the third dielectric layer (5), and the thickness of the third metal layer (6) is 0.035 mm.

8. The wide-angle stealth absorbing metasurface according to claim 1, characterized in that: The second dielectric layer (3) is an air layer with a thickness of 45 mm, used to cascade the anti-reflection layer and the microwave absorbing layer.

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