Broadband wave-absorbing metasurface with adjustable wave-transmitting window

Abstract

The invention discloses a broadband wave-absorbing metasurface with an adjustable wave-transmitting window, relates to the technical field of antennas, and particularly aims to solve the problems that in the background technology, on the basis that out-of-band wave absorption can be achieved, a frequency selective surface with an adjustable transmission frequency band needs a via hole in structure, meanwhile, the frequency selection characteristic is poor, and the frequency selection efficiency is high. Although a square ring gap structure can regulate and control the transmission frequency band, the transmission frequency band of the single-layer frequency selective surface is narrow, and the out-of-band absorption characteristic is poor. According to the broadband wave-absorbing metasurface with the adjustable wave-transmitting window, the broadband wave-absorbing metasurface with the adjustable wave-transmitting window is composed of the impedance absorbing surface, the medium transmission layer and the adjustable transmissivity surface, transmission frequency bands can be dynamically switched, out-of-band absorption is achieved, the structure is simple, and corresponding wave-transmitting and wave-absorbing adjusting operation is convenient. Moreover, the metasurface can be produced in batches, is good in controllability, has broadband response, and can be used for a stealth antenna housing.

Description

Technical Field

[0001] The present invention belongs to the technical field of antennas, and in particular relates to a broadband wave-absorbing metasurface with an adjustable wave-transmitting window. Background Art

[0002] Frequency selective surfaces are an important means to achieve stealth for aircraft radomes. However, traditional frequency selective surfaces can only achieve in-band transmission and out-of-band reflection. By loading an absorbing layer, out-of-band absorption can be achieved while ensuring in-band transmission. However, these solutions are still static and cannot adapt well to the complex and changing electromagnetic environment in the future. Therefore, by loading tunable devices, a reconfigurable frequency selective surface is realized.

[0003] At present, the method of realizing reconfigurable frequency selective surface is mainly to load diodes in the structure and realize the switching of transmission frequency through voltage regulation. For example, in the paper entitled "Broadband Frequency-Selective Rasorber With Varactor-Tunable Interabsorption Band Transmission Window" published by Lijie Wu, Shuomin Zhong and others in Volume 67 of IEEE TRANSACTIONS ONANTENNAS AND PROPAGATION in 2019, a frequency selective surface with adjustable frequency band based on varactor diode was proposed, which can also realize out-of-band absorption. However, the designed structure requires vias and has poor frequency selection characteristics; the patent "Adjustable metasurface with integrated absorption and transmission covering C-band with transmission window and its design method" applied by Ma Yungui and others proposed a square ring gap structure that can adjust the transmission frequency band, but its disadvantage is that the single-layer frequency selective surface has a narrow transmission frequency band and poor out-of-band absorption characteristics. In the existing design, there is no technology that can realize broadband transmission frequency band adjustment and good out-of-band absorption at the same time, and improve the structural performance through multi-layer cascade connection.

[0004] Therefore, it is urgent to design a broadband wave-absorbing metasurface with an adjustable wave-transmitting window to solve the above problems. Summary of the invention

[0005] In view of the problems existing in the above-mentioned prior art, the frequency selective surface with adjustable transmission frequency band, on the basis of being able to achieve out-of-band absorption, requires vias and has poor frequency selection characteristics, and the square ring gap structure can adjust the transmission frequency band, but its single-layer frequency selective surface has a narrow transmission frequency band and poor out-of-band absorption characteristics. The purpose of the present invention is to provide a broadband absorbing metasurface with adjustable wave transmission window, which is composed of an impedance absorption surface, a dielectric transmission layer and an adjustable transmittance surface, can dynamically switch the transmission frequency band, and achieve out-of-band absorption at the same time, and has a simple structure, and the corresponding wave transmission and absorption adjustment operations are convenient.

[0006] In order to achieve the above object, the technical solution adopted by the present invention is as follows:

[0007] A broadband wave-absorbing metasurface with an adjustable wave-transmitting window, wherein the preparation steps of the metasurface include:

[0008] S1. Prepare an impedance absorbing surface of a metasurface, wherein the impedance absorbing surface comprises impedance absorbing units arranged periodically and equidistantly, and the impedance absorbing units are composed of a plurality of metal structures and a lossy medium electrically connected to the metal structures;

[0009] S2. Preparing a dielectric transmission layer of the metasurface, and printing an impedance absorption unit on one side of the dielectric transmission layer;

[0010] S3. Prepare an adjustable transmittance surface of a metasurface, wherein the adjustable transmittance surface includes adjustable transmittance units arranged periodically and at equal intervals, and the adjustable transmittance units are bonded to the other side of the medium transmission layer, and the adjustable transmittance unit includes a left transmission layer, a middle transmission layer and a right transmission layer that are bonded to each other.

[0011] Preferably, in step S3, the left transmission layer includes a metal patch 1, a dielectric layer 1 and a varactor diode, the metal patches 1 are periodically arranged at equal intervals on one side of the dielectric layer 1; the varactor diode is arranged between every two metal patches 1 in the horizontal direction to connect the adjacent metal patches 1 in the horizontal direction.

[0012] Preferably, in step S3, the middle transmission layer comprises a metal grid and a second dielectric layer, the metal grid is printed on one side of the second dielectric layer, and the other side of the second dielectric layer is bonded to the right transmission layer.

[0013] Preferably, in step S3, the right transmission layer includes metal patch 2, an adjustable device and an adjustable device. Metal patch 2 has the same structure as metal patch 1 and is periodically and evenly arranged on the other side of dielectric layer 2 and is set at 90° relative to metal patch 1. The adjustable device is set between every two metal patches 2 in the vertical direction to connect adjacent metal patches 2 in the vertical direction.

[0014] Preferably, the materials of the dielectric transmission layer, the dielectric layer 1 and the dielectric layer 2 are isotropic dielectric materials.

[0015] Preferably, the metasurface realizes wave transmission in the 4.8 GHz-12.2 GHz band, and based on the wave-transmitting band, realizes an out-of-band absorption rate greater than 90%.

[0016] In a second aspect, the present invention provides an application of the broadband wave-absorbing metasurface with adjustable wave-transmitting window in a stealth antenna cover.

[0017] The beneficial effects of the present invention are as follows: the present invention discloses a broadband wave-absorbing metasurface with an adjustable wave-transmitting window. Compared with the prior art, the present invention has the following improvements:

[0018] (1) The broadband absorbing metasurface with adjustable wave-transmitting window of the present invention realizes a wide range of movement of the wave-transmitting frequency band while ensuring absorption outside the band, and has a simple structure and is easy to operate to adjust the wave-transmitting and wave-absorbing effects. The metasurface of the present invention can be mass-produced, has good controllability, and has a broadband response, and can be used for stealth radomes.

[0019] (2) The present invention achieves the effects of efficient transmission in the wave transmission band and efficient absorption outside the wave transmission band through the design of the impedance absorption surface, and has a simple structure and is easy to operate to adjust the wave transmission and absorption effects.

[0020] (3) The present invention solves the problem of the movement of the wave-transmitting frequency band by designing an adjustable transmittance surface. The present invention has a simple structure and is easy to operate to adjust the movement effect. The wave-transmitting frequency band within the absorption band can be moved only by voltage regulation, which can greatly save costs and reduce adjustment time. At the same time, it can adapt to the application of antenna covers in various complex electromagnetic environments. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 It is a schematic diagram of the overall structure of the broadband wave-absorbing metasurface with adjustable wave-transmitting window of the present invention;

[0022] Figure 2 It is a front schematic diagram of the impedance absorbing surface of the present invention;

[0023] Figure 3 This is a schematic diagram of the structure of the adjustable transmittance surface of the present invention;

[0024] Figure 4 This is a schematic diagram of the structure of the left transmission layer of the present invention;

[0025] Figure 5 Schematic diagram of the transmission layer structure in the present invention;

[0026] Figure 6 It is a schematic diagram of the structure of the right transmission layer of the present invention;

[0027] Figure 7 This is a transmission simulation performance diagram of the broadband wave-absorbing metasurface with adjustable wave-transmitting window of the present invention under different capacitances of the varactor diode;

[0028] Figure 8 This is a diagram of the simulated wave absorption performance of the broadband wave absorbing metasurface with adjustable wave-transmitting window of the present invention under different capacitances of the varactor diode;

[0029] Among them: 1. Impedance absorption surface; 101. Metal structure; 102. Loss medium; 2. Dielectric transmission layer; 3. Adjustable transmittance surface; 301. Left transmission layer; 301-1. Metal patch one; 301-2. Dielectric layer one; 301-3. Varactor diode; 302. Middle transmission layer; 302-1. Metal grid; 302-2. Dielectric layer two; 303. Right transmission layer; 303-1. Metal patch two; 303-2. Adjustable device. DETAILED DESCRIPTION

[0030] In order to enable those skilled in the art to better understand the technical solution of the present invention, the technical solution of the present invention is further described below in conjunction with the accompanying drawings and embodiments.

[0031] Example:

[0032] See attached Figure 1-6 A broadband wave-absorbing metasurface with an adjustable wave-transmitting window is shown, comprising an impedance absorption surface 1, a dielectric transmission layer 2, and an adjustable transmittance surface 3, wherein the impedance absorption surface 1 and the adjustable transmittance surface 3 are respectively printed on both sides of the dielectric transmission layer 2; the impedance absorption surface 1 is used for efficient transmission in the wave-transmitting frequency band and efficient absorption outside the wave-transmitting frequency band; the adjustable transmittance surface 3 is used for realizing the movement of the wave-transmitting frequency band;

[0033] Specific reference attached Figure 2 As shown, the impedance absorbing surface 1 is composed of a plurality of impedance absorbing units arranged periodically and at equal intervals, wherein the impedance absorbing unit includes a metal structure 101 and a lossy medium 102. The material of the metal structure 101 can be selected from low-loss metals such as copper, gold, and silver. The metal structure 101 and the lossy medium 102 are electrically connected. The metal structure 101 is composed of metal lines, and the lossy medium 102 is used to connect the metal structure 101.

[0034] Preferably, in this embodiment, there are four metal structures 101, which are symmetrically arranged, and there are eight lossy dielectrics 102, one end of each two lossy dielectrics 102 is connected to the output end and the input end of a metal structure 101, respectively, and the other end is connected to the end of the adjacent lossy dielectric 102, so that the four metal structures 101 and the eight lossy dielectrics 102 form a closed loop circuit;

[0035] By adjusting the width of the metal structure 101, the area of ​​the lossy medium 102, and the width of the metal structure 101 and the overlapping area of ​​the lossy medium 102, the effect of efficient transmission in the wave transmission band and efficient absorption outside the wave transmission band can be achieved. Specifically, the dielectric transmission layer 2 is composed of an isotropic dielectric material, and the thickness of the dielectric transmission layer is: 0.1*λ-0.5*λ, where λ is the central wavelength of the wave transmission band, and is selected as 8mm in this embodiment;

[0036] Specific reference attached Figure 3 As shown, the adjustable transmittance surface 3 includes adjustable transmittance units arranged periodically and at equal intervals, and the adjustable transmittance unit includes a left transmission layer 301, a middle transmission layer 302, and a right transmission layer 303 bonded together; the movement of the wave transmission frequency band can be achieved by changing the capacitance value of the varactor diode 301-3 and the adjustable device 303-2;

[0037] See attached Figure 4 As shown, the left transmission layer 301 includes a metal patch 301-1 and a dielectric layer 301-2. The metal patch 301-1 is a sheet structure, and the material can be selected from low-loss metals such as gold, silver, and copper. The metal patches 301-1 are periodically arranged on the surface of the dielectric layer 301-2, and the other side of the dielectric layer 301-2 is bonded to the middle transmission layer 302; and no electrical connection is formed between every two metal patches 301-1; wherein the dielectric layer 301-2 is composed of an isotropic dielectric material, which can be Rogers 4003C, with a thickness of 0.1*λ-0.5*λ, λ is the central wavelength of the transmission frequency band, and the thickness is preferably 0.2mm in this embodiment; a variable capacitance diode 301-3 is loaded between two metal patches 301-1 in the same row in the horizontal direction, so as to adjust the transmission frequency band of the x-polarized electromagnetic wave;

[0038] See attached Figure 5 As shown, the medium transmission layer 302 includes a metal grid 302-1 and a second dielectric layer 302-2. The metal grid 302-1 is printed on one surface of the second dielectric layer 302-2, and its material can be selected from low-loss metals such as gold, silver, and copper; wherein the second dielectric layer 302-2 is composed of an isotropic dielectric material, which can be Rogers 4003C, with a thickness of 0.1*λ-0.5*λ, λ is the central wavelength of the transmission frequency band, and the thickness is preferably 0.2mm in this embodiment;

[0039] See attached Figure 6 As shown, the right transmission layer 303 includes a second metal patch 303-1 and an adjustable device 303-2. Preferably, the adjustable device 303-2 can be a varactor diode or a switching diode. The second metal patch 303-1 and the adjustable device 303-2 are arranged on the other surface of the second dielectric layer 302-2, and the structure of the second metal patch 303-1 is the same as that of the first metal patch 301-1. It is printed at 90° relative to the first metal patch 301-1, that is, the first metal patch 301-1 is rotated 90° to the setting state of the second metal patch 303-1. The adjustable device 303-2 is arranged between two second metal patches 303-1 in the same vertical row, and is used to adjust the transmission frequency band of the y-polarized electromagnetic wave; the adjustable device 303-2 and the varactor diode 301-3 are perpendicular to each other;

[0040] The broadband absorbing metasurface with adjustable wave-transmitting window of the present embodiment realizes the movement of the wave-transmitting frequency band while ensuring the out-of-band absorption mechanism as follows: the impedance absorbing surface 1 can generate resonance in the resistive dielectric absorption layer to introduce an efficient transmission window, and the dielectric transmission layer 2 provides the necessary isolation; by adjusting the capacitance value of the adjustable device 303-2 and the varactor diode 301-3 in the adjustable transmittance surface 3, the structure of the adjustable transmittance surface 3 is changed to match different electromagnetic waves, and the movement of the wave-transmitting frequency band is realized at the same time; the broadband absorbing metasurface with adjustable wave-transmitting window composed of the impedance absorbing surface 1, the dielectric transmission layer 2 and the adjustable transmittance surface 3 realizes a large range of movement of the wave-transmitting frequency band while ensuring out-of-band absorption.

[0041] This embodiment also provides steps for preparing a broadband wave-absorbing metasurface with an adjustable wave-transmitting window, and the specific steps include:

[0042] S1. Prepare an impedance absorbing surface 1 of a metasurface, wherein the impedance absorbing surface 1 comprises impedance absorbing units arranged periodically and equidistantly, and the impedance absorbing unit comprises a plurality of metal structures 101 and a lossy medium 102 electrically connected to the metal structure 101;

[0043] S2. Preparing a metasurface dielectric transmission layer 2, and printing an impedance absorption unit on one side of the dielectric transmission layer 2;

[0044] S3. Prepare an adjustable transmittance surface 3 of a metasurface, wherein the adjustable transmittance surface 3 includes adjustable transmittance units arranged periodically and at equal intervals, and the adjustable transmittance units are bonded to the other side of the medium transmission layer 2, wherein the adjustable transmittance unit includes a left transmission layer 301, a middle transmission layer 302, and a right transmission layer 303 that are bonded to each other.

[0045] In step S3, the left transmission layer 301 includes a metal patch 301-1, a dielectric layer 301-2 and a varactor diode 301-3. The metal patch 301-1 is periodically arranged at equal intervals on one side of the dielectric layer 301-2; the varactor diode 301-3 is arranged between every two metal patches 301-1 in the horizontal direction to connect the adjacent metal patches 301-1 in the horizontal direction.

[0046] In step S3 , the middle transmission layer 302 includes a metal grid 302 - 1 and a second dielectric layer 302 - 2 . The metal grid 302 - 1 is printed on one side of the second dielectric layer 302 - 2 , and the other side of the second dielectric layer 302 - 2 is bonded to the right transmission layer 303 .

[0047] In step S3, the right transmission layer 303 includes a metal patch 2 303-1, an adjustable device 303-2 and an adjustable device 303-2. The metal patch 2 303-1 has the same structure as the metal patch 1 301-1, and is periodically arranged at equal intervals on the other side of the dielectric layer 2 302-2, and is set at 90° relative to the metal patch 1 301-1. The adjustable device 303-2 is set between every two metal patches 2 303-1 in the vertical direction to connect adjacent metal patches 2 303-1 in the vertical direction.

[0048] in, Figure 7 The curve of the relationship between the transmittance and the frequency and the capacitance value of the varactor diode of the present invention is disclosed, wherein the horizontal axis is the frequency. As can be seen from the figure, with the change of the capacitance value, the transmission band moves from 12.2GHz to 4.8GHz, and the transmittance is greater than 90%. Here, only a few special capacitance values ​​are selected for illustration. In fact, the transmission band can take any value between 4.8GHz and 12.2GHz.

[0049] Figure 8 The invention discloses a curve showing the relationship between the absorption rate and the frequency and the capacitance value of the varactor diode, wherein the horizontal axis is the frequency. As the capacitance value changes, the wave absorption frequency band can change with the wave transmission frequency band, ensuring good absorption outside the band, and the absorption rate outside the band is greater than 90%. Compared with the disclosed wave absorption and wave transmission integrated frequency selective surface, the invention can achieve a large range of movement of the wave transmission frequency band while ensuring absorption outside the band.

[0050] The above shows and describes the basic principles, main features and advantages of the present invention. It should be understood by those skilled in the art that the present invention is not limited to the above embodiments, and the above embodiments and descriptions are only for explaining the principles of the present invention. Without departing from the spirit and scope of the present invention, the present invention may have various changes and improvements, which fall within the scope of the present invention to be protected. The scope of protection of the present invention is defined by the attached claims and their equivalents.

Claims

1. A broadband wave-absorbing metasurface with adjustable wave-transmitting window. Features: The preparation steps of the super surface include: S1. preparing an impedance absorbing surface (1) of a metasurface, wherein the impedance absorbing surface (1) comprises impedance absorbing units arranged periodically and at equal intervals, wherein the impedance absorbing units comprise a plurality of metal structures (101) and a lossy medium (102) electrically connected to the metal structures (101); S2. Preparing a dielectric transmission layer (2) of the metasurface, and printing the impedance absorption unit on one side of the dielectric transmission layer (2); S3. Prepare an adjustable transmittance surface (3) of a metasurface, wherein the adjustable transmittance surface (3) includes adjustable transmittance units arranged periodically and at equal intervals, and the adjustable transmittance units are bonded to the other side of the medium transmission layer (2), wherein the adjustable transmittance unit includes a left transmission layer (301), a middle transmission layer (302) and a right transmission layer (303) which are arranged in contact with each other.

2. According to claim 1, a broadband wave-absorbing metasurface with an adjustable wave-transmitting window, Features: In step S3, the left transmission layer (301) includes a metal patch one (301-1), a dielectric layer one (301-2) and a varactor diode (301-3), wherein the metal patch one (301-1) is periodically arranged at equal intervals on one side of the dielectric layer one (301-2), and the varactor diode (301-3) is arranged between every two metal patches one (301-1) in the horizontal direction to connect the adjacent metal patches one (301-1) in the horizontal direction.

3. According to claim 2, a broadband wave-absorbing metasurface with an adjustable wave-transmitting window, Features: In step S3, the middle transmission layer (302) includes a metal grid (302-1) and a second dielectric layer (302-2), the metal grid (302-1) is printed on one side of the second dielectric layer (302-2), and the other side of the second dielectric layer (302-2) is bonded to the right transmission layer (303).

4. The broadband wave-absorbing metasurface with adjustable wave-transmitting window according to claim 2, Features: In step S3, the right transmission layer (303) includes a metal patch 2 (303-1), an adjustable device (303-2) and an adjustable device (303-2). The metal patch 2 (303-1) has the same structure as the metal patch 1 (301-1), and is periodically arranged at equal intervals on the other side of the dielectric layer 2 (302-2), and is arranged at 90 degrees relative to the metal patch 1 (301-1). The adjustable device (303-2) is arranged between every two metal patches 2 (303-1) in the vertical direction to connect adjacent metal patches 2 (303-1) in the vertical direction.

5. According to claim 4, a broadband wave-absorbing metasurface with an adjustable wave-transmitting window, Features: The materials of the dielectric transmission layer (2), the dielectric layer 1 (301-2) and the dielectric layer 2 (302-2) are isotropic dielectric materials.

6. The broadband wave-absorbing metasurface with adjustable wave-transmitting window according to claim 1, Features: The metasurface is wave-transmissive in the 4.8 GHz-12.2 GHz band, and based on the wave-transmissive band, achieves an out-of-band absorption rate greater than 90%.

7. Application of a broadband absorbing metasurface with an adjustable wave-transmitting window according to claims 1-6 in a stealth radome.

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