A broadband absorbing metasurface with adjustable wave transmission window

Abstract

This invention discloses a broadband absorbing metasurface with an adjustable transmission window, relating to the field of antenna technology. Specifically, it addresses the problems in the prior art where, while achieving out-of-band absorption, frequency-selective surfaces with adjustable transmission bands require vias and suffer from poor frequency selectivity, and where square ring slot structures, although capable of adjusting the transmission band, have narrow single-layer frequency-selective surfaces with poor out-of-band absorption characteristics. By providing a broadband absorbing metasurface with an adjustable transmission window, composed of an impedance-absorbing surface, a dielectric transmission layer, and an adjustable transmittance surface, the invention allows for dynamic switching of the transmission band while simultaneously achieving out-of-band absorption. Furthermore, the structure is simple, and the corresponding transmission and absorption adjustment operations are convenient. This metasurface can be mass-produced, offers good controllability, and has a wideband response, making it suitable for use in stealth radomes.

Description

Technical Field

[0001] This invention belongs to the field of antenna technology, specifically relating to a broadband absorbing metasurface with an adjustable wave transmission window. Background Technology

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

[0003] Currently, the main method for achieving reconfigurable frequency-selective surfaces is to load diodes into the structure and switch the transmission frequency through voltage regulation. For example, in their 2019 paper "Broadband Frequency-Selective Rasorber With Varactor-Tunable Interabsorption Band Transmission Window" published in Volume 67 of IEEE Transactions on Antennas and Propagation, Lijie Wu, Shuomin Zhong, et al. proposed a frequency-selective surface with tunable transmission frequency band based on a varactor diode, which can also achieve out-of-band absorption. However, the designed structure requires vias and has poor frequency selectivity. The patent application by Ma Yungui et al., "Transmission Window Covering C-Band Tunable Metasurface with Integrated Absorption and Transmission and Its Design Method," proposes a square ring slit structure that can regulate the transmission frequency band, but its drawbacks are a narrow transmission frequency band and poor out-of-band absorption characteristics in a single-layer frequency-selective surface. In existing designs, there is no technology that can achieve tunable broadband transmission frequency band while simultaneously achieving good out-of-band absorption, and multi-layer cascading is used to improve structural performance.

[0004] Therefore, there is an urgent need to design a broadband absorbing metasurface with an adjustable wave transmission window to solve the above problems. Summary of the Invention

[0005] To address the shortcomings of existing technologies, such as the need for vias and poor frequency selectivity in the structure of frequency-selective surfaces with adjustable transmission bands while achieving out-of-band absorption, and the narrow transmission band and poor out-of-band absorption characteristics of square ring slot structures, the present invention aims to provide a broadband absorbing metasurface with adjustable transmission windows. This metasurface comprises an impedance-absorbing surface, a dielectric transmission layer, and an adjustable transmittance surface. It allows for dynamic switching of the transmission band while simultaneously achieving out-of-band absorption. Furthermore, its simple structure and convenient transmission and absorption adjustment operations further enhance its advantages.

[0006] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

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

[0008] S1. Prepare an impedance absorption surface of a metasurface, wherein the impedance absorption surface comprises periodically and equally spaced impedance absorption units, and the impedance absorption units consist of several metal structures and a loss medium electrically connected to the metal structures.

[0009] S2. Prepare a dielectric transport layer on a metasurface and print impedance absorption units on one side of the dielectric transport layer;

[0010] S3. Prepare a metasurface with adjustable transmittance, wherein the adjustable transmittance surface comprises periodically and equally spaced adjustable transmittance units, and the adjustable transmittance units are bonded to the other side of the dielectric transport layer, wherein the adjustable transmittance unit comprises a left transmission layer, a middle transmission layer and a right transmission layer that are bonded together.

[0011] Preferably, in step S3, the left transmissive layer includes a metal patch, a dielectric layer, and a varactor diode. The metal patches are periodically and equally spaced on one side of the dielectric layer. The varactor diode is disposed between every two metal patches in the horizontal direction, connecting adjacent metal patches in the horizontal direction.

[0012] Preferably, in step S3, the middle transmission layer includes a metal mesh and a second dielectric layer. The metal mesh 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 transmissive layer includes a second metal patch, an adjustable device, and an adjustable device. The second metal patch has the same structure as the first metal patch and is periodically and equally spaced on the other side of the second dielectric layer, and is set at 90° relative to the first metal patch. The adjustable device is set between every two second metal patches in the vertical direction to connect adjacent second metal patches in the vertical direction.

[0014] Preferably, the materials of the medium transport layer, the first medium layer, and the second medium layer are isotropic medium materials.

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

[0016] In a second aspect, the present invention provides an application of the broadband absorbing metasurface with adjustable transparent window in a stealth radome.

[0017] The beneficial effects of this invention are: This invention discloses a broadband absorbing metasurface with an adjustable wave-transmitting window. Compared with the prior art, the improvement of this invention lies in:

[0018] (1) The broadband absorbing metasurface with adjustable transmission window of the present invention realizes a wide range of transmission frequency band shift while ensuring out-of-band absorption. It has a simple structure and the operation of adjusting the transmission and absorption effects is simple. Moreover, the metasurface of the present invention can be mass-produced, has good controllability, and has a wide frequency response, and can be used in stealth radomes.

[0019] (2) The present invention solves the problem of efficient transmission in the transmission band and efficient absorption outside the transmission band by designing an impedance absorption surface. The structure is simple and the operation of adjusting the transmission and absorption effects is simple.

[0020] (3) The present invention solves the problem of shifting the transmission frequency band by designing an adjustable transmittance surface. The structure is simple and the operation of adjusting the shifting effect is simple. The shifting of the transmission frequency band within the absorption band can be achieved by voltage regulation alone, which can greatly save costs and reduce adjustment time. At the same time, it can adapt to the application of radomes in various complex electromagnetic environments. Attached Figure Description

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

[0022] Figure 2 This is a front view of the impedance absorption surface of the present invention;

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

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

[0025] Figure 5 This is a schematic diagram of the transmission layer structure in this invention;

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

[0027] Figure 7The transmission simulation performance of the broadband absorbing metasurface with adjustable transmission window of the present invention under different capacitances of a varactor diode is shown in the figure.

[0028] Figure 8 The simulation results show the absorption performance of the broadband absorbing metasurface with adjustable wave transmission window of the present invention under different capacitances of a varactor diode.

[0029] Wherein: 1. Impedance absorption surface; 101. Metal structure; 102. Loss dielectric; 2. Dielectric transport 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 mesh; 302-2. Dielectric layer two; 303. Right transmission layer; 303-1. Metal patch two; 303-2. Adjustable device. Detailed Implementation

[0030] To enable those skilled in the art to better understand the technical solutions of the present invention, the technical solutions of the present invention will be further described below in conjunction with the accompanying drawings and embodiments.

[0031] Example:

[0032] See attached document Figure 1-6 The broadband absorbing metasurface with adjustable transmission window shown includes an impedance absorbing surface 1, a dielectric transmission layer 2, and an adjustable transmittance surface 3, with the impedance absorbing surface 1 and the adjustable transmittance surface 3 respectively printed on both sides of the dielectric transmission layer 2; the impedance absorbing surface 1 is used for efficient transmission in the transmission frequency band and efficient absorption outside the transmission frequency band; the adjustable transmittance surface 3 is used to realize the shift of the transmission frequency band.

[0033] For details, please refer to the attached document. Figure 2 As shown, the impedance absorption surface 1 is composed of several periodically and equally spaced impedance absorption units. The impedance absorption unit includes a metal structure 101 and a loss medium 102. The metal structure 101 can be made of low-loss metals such as copper, gold, and silver. The metal structure 101 and the loss medium 102 are electrically connected. The metal structure 101 is composed of metal lines, and the loss medium 102 is used to connect the metal structure 101.

[0034] Preferably, in this embodiment, there are 4 metal structures 101 arranged symmetrically, and 8 loss media 102. One end of every two loss media 102 is connected to the output and input ends of a metal structure 101, respectively, and the other end is connected to the end of the adjacent loss media 102, so that the four metal structures 101 and the eight loss media 102 form a closed loop circuit.

[0035] By adjusting the width of the metal structure 101, the area of ​​the loss medium 102, and the overlapping area of ​​the width of the metal structure 101 and the loss medium 102, efficient transmission in the transmission band and efficient absorption outside the 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: , where λ is the center wavelength of the transparent radio frequency band, which is selected as 8mm in this embodiment;

[0036] For details, please refer to the attached document. Figure 3 As shown, the adjustable transmittance surface 3 includes periodically spaced adjustable transmittance units, each of which includes a left transmittance layer 301, a middle transmittance layer 302, and a right transmittance layer 303 bonded together. The transmission frequency band can be shifted by changing the capacitance values ​​of the varactor diode 301-3 and the adjustable device 303-2.

[0037] See attached document 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 has a sheet-like structure and can be made of low-loss metals such as gold, silver, or 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. No electrical connection is formed between any two metal patches 301-1. The dielectric layer 301-2 is composed of an isotropic dielectric material, such as Rogers 4003C, with a thickness of [missing information]. λ is the center wavelength of the radio frequency transmission band, and the thickness is preferably 0.2 mm in this embodiment; a varactor diode 301-3 is loaded between two metal patches 301-1 in the same horizontal row to adjust the radio frequency transmission band of the x-polarized electromagnetic wave.

[0038] See attached document Figure 5 As shown, the intermediate transmission layer 302 includes a metal mesh 302-1 and a dielectric layer 302-2. The metal mesh 302-1 is printed on one surface of the dielectric layer 302-2, and its material can be selected as a low-loss metal such as gold, silver, or copper. The dielectric layer 302-2 is composed of an isotropic dielectric material, such as Rogers 4003C, with a thickness of [missing information]. λ is the center wavelength of the transparent radio frequency band, and the thickness is preferably 0.2 mm in this embodiment;

[0039] See attached document Figure 6As shown, the right transmissive 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 disposed on the other side of the second dielectric layer 302-2. 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 a 90° angle relative to the first metal patch 301-1, that is, the second metal patch 303-1 is set in the configuration state when the first metal patch 301-1 is rotated 90°. The adjustable device 303-2 is disposed between two pairs of 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 is perpendicular to the varactor diode 301-3.

[0040] The broadband absorbing metasurface with adjustable transmission window in this embodiment achieves both frequency band shifting and out-of-band absorption through the following mechanism: the impedance absorbing surface 1 can generate resonance in the resistive dielectric absorbing layer to introduce a highly efficient transmission window, and the dielectric transmission layer 2 provides the necessary isolation; by adjusting the capacitance values ​​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 can be changed to match different electromagnetic waves, while simultaneously achieving frequency band shifting; the broadband absorbing metasurface with adjustable transmission window, composed of the impedance absorbing surface 1, the dielectric transmission layer 2, and the adjustable transmittance surface 3, achieves a wide range of frequency band shifting while ensuring out-of-band absorption.

[0041] This embodiment also provides the preparation steps for a broadband absorbing metasurface with an adjustable wave transmission window, the specific steps of which include:

[0042] S1. Prepare an impedance absorption surface 1 of a metasurface, wherein the impedance absorption surface 1 includes periodically and equally spaced impedance absorption units, wherein the impedance absorption units consist of a plurality of metal structures 101 and a loss medium 102 electrically connected to the metal structures 101.

[0043] S2. Prepare a dielectric transport layer 2 of the metasurface and print impedance absorption units on one side of the dielectric transport layer 2;

[0044] S3. Prepare a metasurface with adjustable transmittance surface 3, wherein the adjustable transmittance surface 3 comprises periodically and equally spaced adjustable transmittance units, and the adjustable transmittance units are bonded to the other side of the dielectric transport layer 2. The adjustable transmittance unit comprises a left transmittance layer 301, a middle transmittance layer 302 and a right transmittance layer 303 that are bonded together.

[0045] In step S3, the left transmissive layer 301 includes a metal patch 301-1, a dielectric layer 301-2, and a varactor diode 301-3. The metal patches 301-1 are periodically and equally spaced on one side of the dielectric layer 301-2. The varactor diode 301-3 is disposed between every two metal patches 301-1 in the horizontal direction, connecting adjacent metal patches 301-1 in the horizontal direction.

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

[0047] In step S3, the right transmissive layer 303 includes a second metal patch 303-1, an adjustable device 303-2, and an adjustable device 303-3. The second metal patch 303-1 has the same structure as the first metal patch 301-1 and is periodically and equally spaced on the other side of the second dielectric layer 302-2, and is set at 90° relative to the first metal patch 301-1. The adjustable device 303-2 is set between every two second metal patches 303-1 in the vertical direction, connecting adjacent second metal patches 303-1 in the vertical direction.

[0048] in, Figure 7 To disclose the relationship between the transmittance of this invention and the frequency and the capacitance value of the varactor diode, the horizontal axis represents frequency. As can be seen from the figure, as the capacitance value changes, the transmission band shifts from 12.2 GHz to 4.8 GHz, with transmittance greater than 90% in all cases. Only a few specific capacitance values ​​are selected for illustration here; in reality, the transmission frequency band can be any value between 4.8 GHz and 12.2 GHz.

[0049] Figure 8 This invention discloses the relationship between the absorption rate and the frequency and the capacitance value of the varactor diode, where the horizontal axis represents frequency. As the capacitance value changes, the absorption frequency band can vary with the transmission frequency band, ensuring good out-of-band absorption with an out-of-band absorption rate greater than 90%. Compared to previously disclosed integrated absorption and transmission frequency selective surfaces, this invention can achieve a wide range of transmission frequency band shifts while ensuring out-of-band absorption.

[0050] The foregoing has shown and described the basic principles, main features, and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited to the above embodiments. The embodiments and descriptions in the specification are merely illustrative of the principles of the invention. Various changes and modifications can be made to the invention without departing from its spirit and scope, and all such changes and modifications fall within the scope of the present invention as claimed. The scope of protection of this invention is defined by the appended claims and their equivalents.

Claims

1. A broadband absorbing metasurface with an adjustable wave-transmitting window, characterized in that: The preparation steps of the metasurface include: S1. Prepare an impedance absorption surface (1) of a metasurface, wherein the impedance absorption surface (1) comprises periodically and equally spaced impedance absorption units, wherein the impedance absorption units are composed of several metal structures (101) and loss dielectrics (102) electrically connected to the metal structures (101). There are four metal structures (101) arranged symmetrically, and eight loss media (102). Every two loss media (102) form an L-shaped structure. The two ends of the L-shaped structure are connected to two adjacent metal structures (101) respectively, so that the four metal structures (101) and the eight loss media (102) constitute a closed loop circuit. S2. Prepare a dielectric transport layer (2) of a metasurface and print impedance absorption units on one side of the dielectric transport layer (2); S3. Prepare a metasurface with adjustable transmittance (3), wherein the adjustable transmittance surface (3) includes periodically and equally spaced adjustable transmittance units, and the adjustable transmittance units are bonded to the other side of the dielectric transport layer (2). The adjustable transmittance units are composed of a left transmission layer (301), a middle transmission layer (302) and a right transmission layer (303) that are bonded together. 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 and equally spaced on one side of the dielectric layer (301-2). The metal patch (301-1) is a cross-shaped metal patch. The varactor diode (301-3) is disposed between every two metal patches (301-1) in the horizontal direction, connecting adjacent metal patches (301-1) in the horizontal direction. In step S3, the middle transmission layer (302) includes a metal mesh (302-1) and a dielectric layer (302-2). The metal mesh (302-1) is printed on one side of the dielectric layer (302-2), and the other side of the dielectric layer (302-2) is bonded to the right transmission layer (303). The metal mesh (302-1) is bonded to the left transmission layer (301). In step S3, the right transmissive layer (303) includes a second metal patch (303-1) and an adjustable device (303-2). The second metal patch (303-1) has the same structure as the first metal patch (301-1) and is periodically and equally spaced on the other side of the second dielectric layer (302-2), and is set at 90° relative to the first metal patch (301-1). In the vertical direction, two adjacent second metal patches (303-1) are connected through the adjustable device (303-2).

2. The broadband absorbing metasurface with adjustable wave-transmitting window according to claim 1, characterized in that: The materials of the medium transport layer (2), the first medium layer (301-2), and the second medium layer (302-2) are isotropic medium materials.

3. The broadband absorbing metasurface with adjustable wave-transmitting window according to claim 1, characterized in that: The metasurface achieves wave transmission in the 4.8GHz-12.2GHz band, and achieves an out-of-band absorption rate of more than 90% within the wave transmission band.

4. The application of a broadband absorbing metasurface with adjustable wave transmission window according to any one of claims 1-3 in a stealth radome.

Images