Wide-angular-domain stealth wave-absorbing metasurface

Abstract

The invention discloses a wide-angular-domain stealth wave-absorbing metasurface, the wave-absorbing metasurface is composed of N * N wave-absorbing units, and each wave-absorbing unit structure comprises an anti-reflection layer, an air layer and an annular wave-absorbing layer; the wave-absorbing unit structurally comprises 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) from top to bottom in sequence, the thickness of an air layer is properly adjusted by loading the anti-reflection metasurface unit, so that the anti-reflection metasurface unit is cascaded with a traditional wave absorbing unit. According to the wave-absorbing metasurface unit and the design method thereof, the absorptivity of the unit under the condition of large-angle oblique incidence is improved, the design process of a wave absorber is simplified, the design requirement of a complex unit structure is avoided, and the complexity of structural design when large-angle incidence is processed is reduced.

Description

Technical Field

[0001] The present invention relates to the field of metamaterial wave absorbing technology, in particular to a metasurface wave absorbing structure with a wide range of incident angles, and belongs to the fields of communication, radar and new artificial electromagnetic materials. Background Art

[0002] As an emerging absorbing material, metamaterials control the propagation direction of electromagnetic waves by freely adjusting the effective dielectric constant and magnetic permeability of the medium, providing more flexible electromagnetic parameter design, achieving wider bandwidth, 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 show different change trends, which makes the absorption efficiency of the absorber drop sharply under large-angle oblique incidence. By using special materials such as graphene to reduce the sensitivity of the unit to the incident angle, or by designing more complex unit structures to achieve wide-angle absorption, it is possible to achieve stable oblique incidence performance within a range of 60°. However, once the incident angle exceeds 60°, the absorption efficiency of the unit will still be significantly reduced. Summary of the invention

[0004] Technical problem: The purpose of the present 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 achieve wide-angle stealth absorbing.

[0005] Technical solution: A wide-angle stealth absorbing metasurface of the present invention is composed of N×N absorbing units, each of which includes an anti-reflection layer, an air layer and an absorbing layer. The absorbing unit structure is, from top to bottom, 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 a 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 an annular absorbing unit.

[0006] The first metal layer includes a large metal square frame and four small metal square frames located at four right angles to the large metal square frame, and two branches are arranged in each small metal square frame.

[0007] The two branches provided in the small metal frame are respectively located at two diagonal corners of the small metal frame, and the two branches are on two diagonal lines of the large metal frame. The length of the branches is 2.6 mm and the width is 0.2 mm.

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

[0009] The side length of the small metal square frame is 5.4 mm, the width is 0.2 mm, and the thickness is 0.035 mm.

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

[0011] The dielectric structures of the first dielectric layer and the third dielectric layer are 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, and the inner diameter of the annular metal patch is 7.8 mm, the outer diameter is 9.8 mm, and the thickness is 0.035 mm.

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

[0014] The second medium layer is an air layer with a thickness of 45 mm, and is used to cascade the anti-reflection layer and the wave absorbing layer.

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

[0016] The present invention achieves the improvement of the absorption performance of the absorbing unit under large-angle oblique incidence conditions by loading an anti-reflection layer metasurface on top of the traditional absorbing unit structure. The absorption performance of the absorber usually decreases significantly with the increase of the incident angle, and it is still challenging to achieve wide-angle absorption through special materials or more complex unit structures. In contrast, the present invention improves the oblique incidence absorption performance and stabilizes the absorption frequency by adding an anti-reflection layer to the traditional absorbing structure, thereby avoiding complex unit design and simplifying the design process. BRIEF DESCRIPTION OF THE DRAWINGS

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

[0018] Figure 2a This is the TE polarization absorption rate curve of the traditional single-layer annular absorbing unit;

[0019] Figure 2b It is the TE polarization absorption rate curve of the wide-angle absorbing metasurface unit;

[0020] Figure 3a This is the polarization absorption rate curve of the traditional single-layer annular absorbing unit TM;

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

[0022] The figure includes: 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 ; a large metal frame 11 , a small metal frame 12 , and branches 13 . DETAILED DESCRIPTION

[0023] The present invention proposes a new wide-angle stealth absorbing metasurface design, which achieves an improvement in absorption rate under large-angle oblique incidence conditions by loading an anti-reflection structure on top of an existing absorber, separated by air in the middle. Compared with the prior art, the present invention simplifies the absorber design process, avoids the design requirements of complex unit structures, and reduces the complexity of structural design when dealing with large-angle incidence.

[0024] The present invention is further described below in conjunction with the accompanying drawings and specific embodiments.

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

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

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

[0028] The first layer is a 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 dielectric constant of 4.3 and a loss tangent of 0.025.

[0035] The dielectric structures of the first dielectric layer 2 and the third dielectric layer 5 are 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, and the inner diameter of the annular metal patch is 7.8 mm, the outer diameter is 9.8 mm and the thickness is 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 medium layer 3 is an air layer with a thickness of 45 mm, and is used to cascade the anti-reflection layer and the wave absorbing layer.

[0039] The first metal layer 1 includes a large metal square frame 11 and four small metal square frames 12 located at four right angles to the large metal square frame 11, and two branches 13 are provided in each small metal square frame 12. The two branches 13 provided in the small metal square frame 12 are respectively located at two diagonals of the small metal square frame 12, and the two branches 13 are on two diagonals of the large metal square frame 11. The two branches 13 provided in the small metal square frame 12 are respectively located at two diagonals of the small metal square frame 12, and the two branches 13 are on two diagonals of the large metal square frame 11, and the length of the branches 13 is 2.6 mm and the width is 0.2 mm.

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

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

[0042] The periodic size of the traditional annular absorber unit is the same as that of the anti-reflection layer unit, both of which are 16mm, to ensure that the array is easy to arrange when several absorber units are arranged periodically. 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 absorption rate within a wide incident angle range of 0-85°. Specifically, when the incident angle is 0-30°, the frequency band with an absorption rate greater than 85% is 5.78-5.83GHz; when the incident angle is 60-80°, the frequency band with an absorption rate greater than 85% is 5.75-5.84GHz; when the incident angle is 85°, the frequency band with an absorption rate greater than 85% is 5.73-5.97GHz. In particular, when the incident angle increases to 80° and 85°, compared with the traditional single-layer annular absorber unit, the absorption peak values ​​are increased from 76% and 51% to 98% and 95%, respectively; and the bandwidths of the metasurface absorbing unit of the present invention with an absorption rate exceeding 90% are 5.71-5.91GHz and 5.75-5.95GHz, respectively, which is also expanded compared with the absorption bandwidth of the traditional single-layer annular absorber unit.

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

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

[0046] The above is only a preferred embodiment of the present invention. It should be noted that, for those skilled in the art, various improvements and optimizations can be made without violating the basic principles of the present invention. These improvements and optimizations should also be included in the protection scope of the present invention.

Claims

1. A wide-angle stealth wave-absorbing metasurface, characterized in that: The metasurface is composed of N×N wave absorbing units, each of which comprises an anti-reflection layer, an air layer and a wave absorbing layer. The wave absorbing unit structure is composed 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) from top to bottom. The first metal layer (1) and the first dielectric layer (2) constitute a unit anti-reflection layer; the second dielectric layer (3) is an air layer. The second metal layer (4), the third dielectric layer (5) and the third metal layer (6) form a ring-shaped wave absorbing unit.

2. The wide-angle stealth absorbing metasurface according to claim 1, characterized in that: The first metal layer (1) comprises a large metal square frame (11) and four small metal square frames (12) located at four right angles to the large metal square frame (11), and two branches (13) are arranged in each small metal square frame (12).

3. The wide-angle stealth absorbing metasurface according to claim 2, characterized in that: The two branches (13) provided in the small metal frame (12) are respectively located at two diagonal corners of the small metal frame (12), and the two branches (13) are on two diagonal lines of the large metal frame (11). The length of the branches (13) is 2.6 mm and the width is 0.2 mm.

4. The wide-angle stealth absorbing metasurface according to claim 3, characterized in that: The side length of the large metal square frame (11) is equal to the period of the wave absorbing unit, the width is 0.1 mm, and the thickness is 0.035 mm.

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

6. 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 dielectric constant of 4.3 and a loss tangent of 0.

025.

7. The wide-angle stealth absorbing metasurface according to claim 1, characterized in that: The dielectric structures of the first dielectric layer (2) and the third dielectric layer (5) are 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.

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

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

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

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