Metasurface system for electromagnetic shielding and transmission window based on mode coupling

Abstract

The application discloses a metasurface system for realizing electromagnetic shielding and transmission window based on mode coupling, which comprises a first metal layer, a dielectric layer and a second metal layer in sequence along the vertical direction; the first metal layer, the dielectric layer and the second metal layer are square structures with the side length of P and the height of h1, h2 and h3 in sequence along the vertical direction; the first metal layer is provided with a first metal slit extending along the horizontal direction, the first metal slit is arranged in parallel with the first side of the first metal layer and symmetrically relative to the center line of the first side; the second metal layer is provided with a second metal slit extending along the vertical direction, the second metal slit is arranged in parallel with the second side of the second metal layer and symmetrically relative to the center line of the second side; the first side and the second side are arranged perpendicularly, and the relative dielectric constant of the dielectric layer is 3.66.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of electronic technology, and in particular to a metasurface system for realizing electromagnetic shielding and transmission window based on mode coupling. BACKGROUND

[0002] With the development of wireless communication technology, the importance of electromagnetic shielding is increasingly prominent, especially in modern communication, intelligent devices, medical devices and other high-tech fields, electromagnetic shielding has become an indispensable technology. Traditional electromagnetic shielding technology mainly relies on metal materials such as aluminum, copper, etc. These metal materials usually absorb or reflect electromagnetic waves through their electrical conductivity and magnetism. However, these traditional materials have some shortcomings, such as heavy weight, high thickness requirement, and difficulty in achieving precise control of specific frequencies. With the increasing demand for more efficient and precise electromagnetic control, meta-surface technology has emerged.

[0003] Metasurface refers to artificial microstructures designed on a sub-wavelength scale, usually composed of periodically arranged micro-units (metallic or dielectric structure units). These units can be designed to control the propagation characteristics of electromagnetic waves. The core feature of metasurface structure is that it can precisely manipulate the propagation behavior of electromagnetic waves at a much smaller scale than the wavelength. By designing the shape, arrangement and material properties of these microstructures, it is possible to control the refraction, reflection, absorption and even diffraction of electromagnetic waves.

[0004] The principle of metasurface electromagnetic shielding technology is based on the local response of metasurface to electromagnetic waves. Specifically, when electromagnetic waves encounter metasurface, the microstructures of metasurface will interact with electromagnetic waves, causing changes in the phase, amplitude and propagation direction of electromagnetic waves. This effect enables metasurface to effectively shield electromagnetic waves of specific frequency bands and guide electromagnetic waves to propagate along a specific path, thereby achieving the effect of shielding and regulating electromagnetic radiation.

[0005] Compared with traditional electromagnetic shielding materials, metasurface electromagnetic shielding technology has many unique advantages. First, metasurface can achieve precise control of specific frequencies, so it can be designed to have high selectivity of electromagnetic shielding effect for different application scenarios. Second, metasurface is thin and light, and can achieve efficient electromagnetic shielding without significantly increasing volume and weight. In addition, the manufacturing process of metasurface material is relatively simple and easy to mass-produce, so it has good economic efficiency and generalizability.

[0006] However, the metasurface electromagnetic shielding technology in the prior art needs to realize polarization conversion and needs to rely on magnetic resonance, which requires the structure of the metasurface electromagnetic shielding system to be about one-fifth of the wavelength, which cannot achieve ultra-thin.

[0007] The above description is only used to assist in understanding the technical solutions of the present application and does not mean to acknowledge that the above description is the prior art. SUMMARY

[0008] The main purpose of the present application is to provide a metasurface system for realizing electromagnetic shielding and transmission window based on mode coupling, which aims to solve the technical problems in the prior art that the metasurface electromagnetic shielding technology needs to realize polarization conversion and needs to rely on magnetic resonance, and the magnetic resonance requires that the structure of the metasurface electromagnetic shielding system must be about one-fifth of the wavelength, which cannot realize ultra-thin technology.

[0009] To achieve the above purpose, the present application provides a metasurface system for realizing electromagnetic shielding and transmission window based on mode coupling, which comprises a first metal layer, a dielectric layer and a second metal layer in sequence along the vertical direction.

[0010] The first metal layer, the dielectric layer and the second metal layer are square structures, and the side length of each is P, and the height along the vertical direction is h1, h2 and h3 in sequence.

[0011] The first metal layer is provided with a first metal slit extending along the horizontal direction, the first metal slit is arranged in parallel with the first side of the first metal layer and symmetrically relative to the center line of the first side; the second metal layer is provided with a second metal slit extending along the vertical direction, the second metal slit is arranged in parallel with the second side of the second metal layer and symmetrically relative to the center line of the second side; the first side and the second side are arranged vertically, and the distance between the center of the first metal slit and the center of the first metal layer and the distance between the center of the second metal slit and the center of the second metal layer are both Delta.

[0012] The height of the first metal layer, the dielectric layer and the second metal layer along the vertical direction is h1, h2 and h3 in sequence, the length of the first metal slit along the horizontal direction is a2, the width along the vertical direction is a1, and the height along the vertical direction is h1; the length of the second metal slit along the horizontal direction is a1, the width along the vertical direction is a2, and the height along the vertical direction is h3.

[0013] The relative dielectric constant of the dielectric layer is 3.66.

[0014] Preferably, in the metasurface system for realizing electromagnetic shielding and transmission window based on mode coupling, the first metal layer and the second metal layer are both copper layers.

[0015] Preferably, in the metasurface system for realizing electromagnetic shielding and transmission window based on mode coupling, the determination method of each parameter in the metasurface system for realizing electromagnetic shielding and transmission window based on mode coupling is as follows:

[0016] Step S210, determining the frequency ω of the two resonance modes according to the formula: ω = c / (2n)s , ω a , a1, a2, P are obtained based on the FDTD super surface simulation model;

[0017] In step S220, initial values of Dlta and h2 are determined according to the obtained P, wherein Dlta≤P / 2, 0.1*P≤h2≤P;

[0018] In step S230, the reflection coefficient r and the transmission coefficient t are calculated according to the following formulas (1) to (3);

[0019]

[0020] In step S240, the shielding effect and the polarization conversion rate are calculated according to the reflection coefficient r and the transmission coefficient t; in step S250, it is judged whether the shielding effect and the polarization conversion rate meet the preset condition;

[0021] In step S260, when the judgment result is no, the next round of loop is continued to be executed in step S220; in step S270, when the judgment result is yes, Dlta and h2 determined in step S220 are taken as the final values; wherein,

[0022] Ψ s is the amplitude of the s-th resonant mode in the system;

[0023] Ψ a is the amplitude of the a-th resonant mode in the system;

[0024] i is the imaginary unit in mathematics;

[0025] Γ s is the radiation damping of the s-th mode, wherein 2Γ s =|d 1s | 2 +|d 2s | 2 ;

[0026] Γ′ s is the absorption damping of the s-th mode;

[0027] Γ a is the radiation damping of the a-th mode, wherein 2Γ a =|d 1a | 2 +|d 2a | 2 ;

[0028] Γ′ a is the absorption damping of the a-th mode;

[0029] X is the far-field coupling strength of the mode a and the mode s, and the calculation formula is as follows:

[0030]

[0031] for d 1s taking complex conjugate;

[0032] for d 2s taking complex conjugate;

[0033] d 1s is the coupling coefficient of the first port and the s-th mode;

[0034] d 1a is the coupling coefficient of the first port and the a-th mode;

[0035] d 2s is the coupling coefficient of the second port and the s-th mode;

[0036] d 2a is the coupling coefficient of the second port and the a-th mode;

[0037] is the amplitude of the input wave propagating along the first port;

[0038] is the amplitude of the output wave propagating along the first port;

[0039] is the amplitude of the output wave propagating along the second port;

[0040] r0 is a constant, taking -1;

[0041] t0 is a constant, taking 0;

[0042] W a is the working frequency point in the a-th mode;

[0043] W s is the working frequency point in the s-th mode;

[0044] W i = i (ω - ω i ) + Γ i + Γ' i , i = s, a;

[0045] ω is 2πf, f is frequency.

[0046] Preferably, in the metasurface system for realizing electromagnetic shielding and transmission window based on mode coupling, in the step S240 of calculating the shielding effect and the polarization conversion rate according to the reflection coefficient r and the transmission coefficient t, the calculation formula of the shielding effect is as follows:

[0047] Shielding effect = 20*log10 (|t|);

[0048] Polarization conversion = 1 - |r| 2 .

[0049] Preferably, in the metasurface system for realizing electromagnetic shielding and transmission window based on mode coupling, the step S250 of judging whether the shielding effect and the polarization conversion rate meet the preset condition comprises:

[0050] Step S251, judging whether the shielding effect is greater than or equal to -20 dB and the polarization conversion rate is greater than or equal to 80%.

[0051] Preferably, in the metasurface system for realizing electromagnetic shielding and transmission window based on mode coupling, the metasurface system has two external ports and two resonant modes.

[0052] Preferably, in the metasurface system for realizing electromagnetic shielding and transmission window based on mode coupling, the square structure is periodically extended to an MxN array in a two-dimensional plane with a period P to form an array metasurface.

[0053] Preferably, in the metasurface system for realizing electromagnetic shielding and transmission window based on mode coupling, M = 23 artificial atoms and N = 23 artificial atoms.

[0054] Preferably, in the metasurface system for realizing electromagnetic shielding and transmission window based on mode coupling, the metasurface system receives y-polarized electromagnetic waves at the transmission end of the metasurface system by normally incidenting x-polarized electromagnetic waves on the surface of the metasurface system to realize electromagnetic shielding and transmission window.

[0055] Preferably, in the metasurface system for realizing electromagnetic shielding and transmission window based on mode coupling, the thickness of the metasurface system is 0.12 mm when the working wavelength is 43 mm.

[0056] The metasurface system provided by this invention comprises, in a vertical direction, a first metal layer, a dielectric layer, and a second metal layer. The first metal layer, dielectric layer, and second metal layer are square structures with side length P and vertical heights h1, h2, and h3, respectively. The first metal layer has a first metal slit extending laterally, parallel to a first side of the first metal layer and symmetrically arranged with respect to the centerline of the first side. The second metal layer has a second metal slit extending longitudinally, parallel to a second side of the second metal layer and symmetrically arranged with respect to the centerline of the second side. The first and second sides are perpendicular, and the center of the first metal slit is perpendicular to the center of the first metal layer. The distance between the center of the second metal seam and the center of the second metal layer is Dlta; the vertical heights of the first metal layer, the dielectric layer, and the second metal layer are h1, h2, and h3, respectively; the horizontal length of the first metal seam is a2, the vertical width is a1, and the vertical height is h1; the horizontal length of the second metal seam is a1, the vertical width is a2, and the vertical height is h3; the relative permittivity of the dielectric layer is 3.66. Through an artificial microstructure containing two resonant modes, electromagnetic shielding and polarization conversion are achieved through coupling between the modes. When x-polarized electromagnetic waves irradiate the metasurface, electromagnetic shielding is achieved through the resonance of the artificial microstructure, and polarization conversion is achieved through the emitted y-polarized electromagnetic waves. This method has advantages such as high efficiency and ultrathinness.

[0057] Furthermore, because the present invention sets two metal seams (a first metal seam and a second metal seam), and the electric field generated at the first metal seam and the second metal seam is an evanescent wave, the evanescent wave will gradually weaken as the distance increases. Therefore, the thickness must be limited to ensure that the two evanescent waves generate a sufficiently strong near-field coupling. It is for this reason that the thickness of this system is ultrathin.

[0058] Furthermore, the metasurface system provided by this invention is unrelated to magnetic resonance and utilizes near-field coupling, thus achieving a thickness of one three-hundred-sixtieth of the wavelength, realizing ultrathinness. For example, when the operating wavelength is 43 mm, the thickness of the metasurface system is 0.12 mm. Attached Figure Description

[0059] Figure 1 The schematic diagram illustrates the metasurface system for achieving electromagnetic shielding and transmission windows based on mode coupling provided by the present invention.

[0060] Figure 2 for Figure 1 Top view of the first metal layer;

[0061] Figure 3 for Figure 1 Top view of the second metal layer;

[0062] Figure 4 A flow chart of a method for determining parameters in a metasurface system for realizing electromagnetic shielding and transmission window based on mode coupling is shown.

[0063] Figure 5 A schematic diagram of near field coupling between upper and lower modes is shown.

[0064] Figure 6 A graph of simulation results of polarization conversion rate (PCR) of the metasurface system is shown.

[0065] 1-first metal layer, 11-first metal slit, 2-dielectric layer, 3-second metal layer, 31-second metal slit.

[0066] The purposes, functional features and advantages of the present application will be further described with reference to the embodiments and the accompanying drawings. DETAILED DESCRIPTION

[0067] The technical solutions of the present application will be described clearly and completely below with reference to the accompanying drawings. Obviously, the described embodiments are only some of the embodiments of the present application, but not all. The present application will be described in detail below with reference to the accompanying drawings and embodiments. It should be noted that the embodiments in the present application and the features in the embodiments can be combined with each other without conflict.

[0068] In the embodiments of the present application, the term "and / or" describes the association relationship of the associated objects, which means that there can be three relationships, for example, A and / or B, which can represent the three cases of A alone, A and B together, and B alone. The character " / " generally represents an "or" relationship between the associated objects before and after it.

[0069] It should be noted that the terms "first", "second" and the like in the specification and claims of the present application and the above-mentioned drawings are used to distinguish similar objects, and do not necessarily describe a specific order or sequence.

[0070] In the embodiments of the present application, the term "a plurality of" means two or more, and other quantifiers are similar.

[0071] In the present application, unless otherwise stated, the orientation words such as "up", "down", "top", "bottom" are generally directed to the directions shown in the drawings, or to the vertical, perpendicular or gravity directions of the components themselves; similarly, for the convenience of understanding and description, "inner" and "outer" refer to the inner and outer relative to the contour of the components themselves, but the above orientation words are not used to limit the present application.

[0072] In order to make the purposes, technical solutions and advantages of the embodiments of the present application clearer, the embodiments of the present application will be described in detail below with reference to the drawings. However, those skilled in the art can understand that, in the embodiments of the present application, many technical details are presented in order to make the readers better understand the present application. However, the technical solutions claimed by the present application can be implemented even without these technical details and based on various changes and modifications of the following embodiments. The division of the following embodiments is for the convenience of description, and should not constitute any limitation on the specific implementation modes of the present application, and the embodiments can be combined and referenced with each other under the premise of no contradiction.

[0073] The structure of a general metasurface system is also a three-layer structure, the outer two layers are metal gratings, and the middle layer is a polarization conversion structure. However, in order to realize polarization conversion, this three-layer structure needs to rely on magnetic resonance, and the magnetic resonance requires that the three-layer structure must be around one-fifth of the wavelength.

[0074] In order to solve the above problems, the present application provides a metasurface system for realizing electromagnetic shielding and transmission window based on mode coupling, as shown in Figures 1 to 3 The metasurface system sequentially includes a first metal layer 1, a dielectric layer 2, and a second metal layer 3 along the vertical direction; the first metal layer 1, the dielectric layer 2, and the second metal layer 3 are square structures, and the side length of each is P, and the height along the vertical direction is h1, h2, and h3 in sequence; the first metal layer 1 is provided with a first metal slit 11 extending along the horizontal direction, the first metal slit 11 is arranged in parallel with the first side of the first metal layer 1 and symmetrically arranged with respect to the center line of the first side; the second metal layer 3 is provided with a second metal slit 31 extending along the vertical direction, the second metal slit 31 is arranged in parallel with the second side of the second metal layer 3 and symmetrically arranged with respect to the center line of the second side; the first side and the second side are arranged vertically, the distance between the center of the first metal slit 11 and the center of the first metal layer 1 and the distance between the center of the second metal slit 31 and the center of the second metal layer 3 are both Delta; the height of the first metal layer 1, the dielectric layer 2, and the second metal layer 3 along the vertical direction is h1, h2, and h3 in sequence, the length of the first metal slit 11 along the horizontal direction is a2, the width along the vertical direction is a1, and the height along the vertical direction is h1; the length of the second metal slit 31 along the horizontal direction is a1, the width along the vertical direction is a2, and the height along the vertical direction is h3; the relative permittivity of the dielectric layer is 3.66.

[0075] The super surface system comprises a first metal layer 1, a dielectric layer 2 and a second metal layer 3 in sequence along a vertical direction; the first metal layer 1, the dielectric layer 2 and the second metal layer 3 are square structures with a side length of P and a vertical height of h1, h2 and h3 in sequence; the first metal layer 1 is provided with a first metal slit 11 extending along a horizontal direction, the first metal slit 11 is arranged in parallel with a first side of the first metal layer 1 and symmetrically relative to a center line of the first side; the second metal layer 3 is provided with a second metal slit 31 extending along a vertical direction, the second metal slit 31 is arranged in parallel with a second side of the second metal layer 3 and symmetrically relative to a center line of the second side; the first side and the second side are arranged perpendicularly, the distance between the center of the first metal slit 11 and the center of the first metal layer 1 and the distance between the center of the second metal slit 31 and the center of the second metal layer 3 are both Dlta; the vertical height of the first metal layer 1, the dielectric layer 2 and the second metal layer 3 is h1, h2 and h3 in sequence, the length of the first metal slit 11 along the horizontal direction is a2, the width along the vertical direction is a1, and the vertical height is h1; the length of the second metal slit 31 along the horizontal direction is a1, the width along the vertical direction is a2, and the vertical height is h3; the relative dielectric constant of the dielectric layer is 3.66, the super surface system comprises two resonant modes, electromagnetic shielding and polarization conversion are realized through coupling between the modes, the super surface is irradiated by an x-polarized electromagnetic wave, electromagnetic shielding is realized through resonant of the artificial microstructure, and y-polarized electromagnetic wave is emitted to realize polarization conversion, and the super surface system has the advantages of high efficiency and ultra-thin thickness.

[0076] The super surface system is not related to magnetic resonance, and near-field coupling is used, so that the thickness can be 1 / 360 of the wavelength, and the thickness of the super surface system is 0.12 mm when the working wavelength is 43 mm.

[0077] Further, the super surface system is based on resonant mode coupling of microstructures, and can shield super wideband electromagnetic waves and realize a specific frequency electromagnetic wave transmission window through the super surface as a bridge.

[0078] Further, the super surface system is based on mode coupling, realizes electromagnetic shielding and transmission window, can be used for electromagnetic shielding, and due to the coupling effect of the mode, the thickness of the device can be very thin, and finally realizes the deflection conversion effect of the transmitted electromagnetic wave and the incident electromagnetic wave with different polarizations.

[0079] In some embodiments, the first metal layer 1 and the second metal layer 3 are both copper layers. In other embodiments, the first metal layer 1 and the second metal layer 3 can also be other conductive metal layers.

[0080] Based on the above super surface system, the square structure is periodically extended in a two-dimensional plane to an MxN array with a period P to form an array super surface. The length (i.e. x direction) and width (y direction) of the super surface system correspond to the total length of M and N artificial atoms. In some embodiments, M = 23 artificial atoms, N = 23 artificial atoms. In other embodiments, M and N can also be set as needed.

[0081] Based on the above super surface system, the x-polarized electromagnetic wave is normally incident on the surface of the super surface system, and the y-polarized electromagnetic wave is received at the transmission end of the super surface system to achieve electromagnetic shielding and transmission window.

[0082] Wherein, the determination method of each parameter in the super surface system based on mode coupling to achieve electromagnetic shielding and transmission window is as shown in Figure 4

[0083] At step S210, the frequencies ω s , ω a of the two resonance modes are obtained based on the FDTD super surface simulation model.

[0084] It should be noted that the frequencies ω s , ω a of the two resonance modes can be the frequency points that want to work, which can be determined as needed. For example, ω s is 7GHz, and ω a is 8GHz.

[0085] When the super surface system includes two resonance modes, s can be 1 and a can be 2, that is, one mode is frequency ω s and the other mode is ω a . Since s and a add up to two modes, the super surface system defaults to two ports. The super surface system has two external ports and two resonance modes.

[0086] The frequencies ω s , ω a are input into the FDTD (Finite-Difference Time-Domain) super surface simulation model to obtain a1, a2, and P. In order to efficiently achieve electromagnetic shielding and polarization effects, the artificial microstructure of the super surface system uses a relatively narrow opening metal slit. Based on the FDTD super surface simulation model, a beam of x-polarized electromagnetic waves is incident on the designed artificial microstructure, and the transmitted light is only one kind of y-polarized electromagnetic wave.

[0087] ​At step S220, initial values of Dlta and h2 are determined according to the obtained P, where Dlta≤P / 2, 0.1*P≤h2≤P. The initial values of Dlta and h2 can be determined according to the preset conditions (Dlta≤P / 2, 0.1*P≤h2≤P). For example, the initial value of Dlta is selected as P / 3, and the initial value of h2 is selected as 0.5*P.

[0088] At step S230, the reflection coefficient r and the transmission coefficient t are calculated according to the following formulas (1) to (3);

[0089]

[0090] wherein,

[0091] Ψ s is the amplitude of the s-th resonant mode in the system;

[0092] Ψ a is the amplitude of the a-th resonant mode in the system;

[0093] i is the imaginary unit in mathematics;

[0094] Γ s is the radiation damping of the s-th mode, where 2Γ s = |d 1s | 2 + |d 2s | 2 ;

[0095] Γ′ s is the absorption damping of the s-th mode;

[0096] Γ a is the radiation damping of the a-th mode, where 2Γ a = |d 1a | 2 + |d 2a | 2 ;

[0097] Γ′ a is the absorption damping of the a-th mode;

[0098] X is the far-field coupling strength between the a-th mode and the s-th mode, and is calculated as follows:

[0099]

[0100] is the complex conjugate of d 1s ;

[0101] is the complex conjugate of d 2s ;

[0102] d1s is the coupling coefficient of the first port and the s-th mode;

[0103] d 1a is the coupling coefficient of the first port and the a-th mode;

[0104] d 2s is the coupling coefficient of the second port and the s-th mode;

[0105] d 2a is the coupling coefficient of the second port and the a-th mode;

[0106] is the amplitude of the input wave propagating along the first port;

[0107] is the amplitude of the output wave propagating along the first port;

[0108] is the amplitude of the output wave propagating along the second port;

[0109] r0 is a constant, taking -1;

[0110] t0 is a constant, taking 0;

[0111] W a is the working frequency point in the a-th mode;

[0112] W s is the working frequency point in the s-th mode;

[0113] W i = i (ω-ω i )+Γ i +Γ′ i , i = s, a;

[0114] ω is 2πf, f is the frequency.

[0115] It should be noted that after a1, a2, Dlta and h2 are determined, the specific values of the above d 1s , d 1a , d 2s , d 2a , and Γ s , Γ′ s , Γ a , Γ′ a , etc. can be obtained through the FDTD super surface simulation model, so that X is also determined, and thus the above parameters are determined. According to the above formula, r and t can be calculated.

[0116] At step S240, the shielding effect and the polarization conversion rate are calculated according to the reflection coefficient r and the transmission coefficient t.

[0117] The shielding effect = 20*log (|t|). 10 (|t|);

[0118] The polarization conversion rate = 1 - |r| 2 .

[0119] At step S250, it is judged whether the shielding effect and the polarization conversion rate meet the preset condition.

[0120] The preset condition can include, but is not limited to, the shielding effect being greater than or equal to -20 dB and the polarization conversion rate being greater than or equal to 80%. Specifically, at step S251, it is judged whether the shielding effect is greater than or equal to -20 dB and the polarization conversion rate is greater than or equal to 80%.

[0121] At step S260, when the judgment result is no, the step S220 is continued to be executed to enter the next round of loop. When the shielding effect and the polarization conversion rate do not meet the preset condition, the Dlta and h2 are reselected at step S220, and then the steps S230 to S250 are continued to be executed until the judgment result is yes.

[0122] At step S270, when the judgment result is yes, the Dlta and h2 determined at step S220 are taken as the final values.

[0123] Figure 5 The near-field coupling schematic diagrams of the upper and lower modes are shown. Figure 6 The polarization conversion rate (PCR) simulation result diagram of the metasurface system is shown. Figure 5 and Figure 6 It can be seen that, in the working waveband, the polarization conversion efficiencies of the two transmission peaks are both above 99%, and the average shielding effect is -36 dB, which indicates that the metasurface system designed in the application not only has a strong electromagnetic shielding effect, but also has a high polarization conversion effect. When the working wavelength is 43 mm, the thickness of the metasurface system can be designed to be less than or equal to 0.12 mm, which is about one three-hundredth and sixty-first of the working wavelength.

[0124] Obviously, the above-described embodiments are only some of the embodiments of the application, but not all the embodiments. Based on the embodiments in the application, other different forms of changes or modifications can be made by those skilled in the art without creative labor, and all should belong to the protection scope of the application.

Claims

1. A metasurface system implementing electromagnetic shielding and transmission windows based on mode coupling, characterized in that, The super surface system comprises a first metal layer, a dielectric layer and a second metal layer in sequence along a vertical direction; The first metal layer, the dielectric layer and the second metal layer are square structures with a side length of P and a vertical height of h1, h2 and h3 in sequence; The first metal layer is provided with a first metal slit extending along a horizontal direction, the first metal slit is arranged in parallel with a first side of the first metal layer and symmetrically relative to a center line of the first side; the second metal layer is provided with a second metal slit extending along a vertical direction, the second metal slit is arranged in parallel with a second side of the second metal layer and symmetrically relative to a center line of the second side; the first side and the second side are arranged perpendicularly, and a center of the first metal slit is away from a center of the first metal layer by a distance Dlta, and a center of the second metal slit is away from a center of the second metal layer by a distance Dlta; The first metal layer, the dielectric layer and the second metal layer have a vertical height of h1, h2 and h3 in sequence, the first metal slit has a horizontal length of a2, a vertical width of a1 and a vertical height of h1, and the second metal slit has a horizontal length of a1, a vertical width of a2 and a vertical height of h3; The relative dielectric constant of the dielectric layer is 3.

66.

2. The metasurface system enabling electromagnetic shielding and transmissive window based on mode coupling of claim 1, wherein, The first metal layer and the second metal layer are both copper layers.

3. The metasurface system enabling electromagnetic shielding and transmissive window based on mode coupling of claim 1, wherein, The method for determining parameters in the super surface system for realizing electromagnetic shielding and transmission window based on mode coupling is as follows: Step S210, according to the frequency ω s 、 ω a of two resonance modes, based on the FDTD super surface simulation model, a1, a2, P are obtained; In step S220, initial values of Dlta and h2 are determined according to the obtained P, wherein Dlta≤P / 2 and 0.1*P≤h2≤P; In step S230, reflection coefficient r and transmission coefficient t are calculated according to the following formulas (1) to (3); In step S240, shielding effect and polarization conversion rate are calculated according to the reflection coefficient r and the transmission coefficient t; in step S250, it is determined whether the shielding effect and the polarization conversion rate meet a preset condition; In step S260, when the determination result is no, step S220 is continued to enter the next round of loop; In step S270, when the determination result is yes, Dlta and h2 determined in step S220 are taken as final values; wherein, Ψ s Amplitude of the s-th resonant mode in the system; Ψ a Amplitude of the a-th resonant mode in the system; i is an imaginary symbol in mathematics; Γ s Γ for the s-th resonant mode, where 2Γ s = |d 1s | 2 + |d 2s | 2 ; Γ′ s absorption damping for the s-th resonance mode; Γ a Γ for the a-th resonance mode, where 2Γ a = |d 1a | 2 + |d 2a | 2 ; Γ′ a absorption damping for the a-th resonance mode; X is the far-field coupling strength of resonance mode a and resonance mode s, and the calculation formula is as follows: for d 1s complex conjugate for d 2s complex conjugate; d 1s is the coupling coefficient for the first port and the s-th resonant mode; d 1a is the coupling coefficient for the first port and the a-th resonant mode; d 2s is the coupling coefficient for the 2nd port and the s-th resonant mode; d 2a K2a is the coupling coefficient for the 2nd port and the a-th resonant mode; A1 is the amplitude of the input wave propagating along the first port; is the amplitude of the output wave propagating along the first port; is the amplitude of the output wave propagating along the second port; r0 is a constant, which is -1; t0 is a constant, which is 0; W a for the a-th resonance mode; W s is the working frequency point under the s-th resonance mode; W i = i(ω - ω i ) + Γ i + Γ' i , i = s, a; ω is 2πf, and f is frequency.

4. The metasurface system enabling electromagnetic shielding and transmissive window based on mode coupling of claim 3, wherein, In step S240, the calculation formula of the shielding effect is as follows: Shielding effect = 20*log 10 (|t|); Polarization conversion = 1 - |r| 2 .

5. The metasurface system enabling electromagnetic shielding and transmissive window based on mode coupling of claim 3, wherein, In step S250, it is determined whether the shielding effect and the polarization conversion rate meet a preset condition, which includes: In step S251, it is determined whether the shielding effect is greater than or equal to -20 dB and the polarization conversion rate is greater than or equal to 80%.

6. The metasurface system enabling electromagnetic shielding and transmissive window based on mode coupling of claim 1, wherein, The super surface system has two external ports and two resonance modes.

7. The metasurface system enabling electromagnetic shielding and transmissive window based on mode coupling of claim 1, wherein, The square structure is periodically extended in a two-dimensional plane to form an M×N array with a period of P, forming an array super surface.

8. The metasurface system enabling electromagnetic shielding and transmissive window based on mode coupling of claim 7, wherein, M=23 artificial atoms, N=23 artificial atoms.

9. The metasurface system enabling electromagnetic shielding and transmissive window based on mode coupling of claim 1, wherein, The metasurface system receives electromagnetic waves of y polarization at the transmission end of the metasurface system by normally incidenting electromagnetic waves of x polarization onto the surface of the metasurface system to realize electromagnetic shielding and a transmission window.

10. The metasurface system enabling electromagnetic shielding and transmissive window based on mode coupling of claim 1, wherein, The thickness of the metasurface system is 0.12 mm when the working wavelength is 43 mm.

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