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

Abstract

The invention discloses a metasurface system for achieving electromagnetic shielding and a transmission window based on mode coupling. The metasurface system sequentially comprises a first metal layer, a dielectric layer and a second metal layer in the vertical direction. The first metal layer, the dielectric layer and the second metal layer are of a square structure, the side length is P, and the heights in the vertical direction are h1, h2 and h3 in sequence; the first metal layer is provided with a first metal seam extending in the transverse direction in a penetrating mode, and the first metal seam and the first edge of the first metal layer are arranged in parallel and are symmetrically arranged relative to the center line of the first edge. The second metal layer is provided with a second metal seam extending in the longitudinal direction in a penetrating mode, and the second metal seam and the second edge of the second metal layer are arranged in parallel and are symmetrically arranged relative to the center line of the second edge. The first side and the second side are vertically arranged, and the relative dielectric constant of the dielectric layer is 3.66.

Description

Technical Field

[0001] The present invention relates to the field of electronic technology, and in particular to a metasurface system that realizes electromagnetic shielding and transmission windows based on mode coupling. Background Art

[0002] With the development of wireless communication technology, the importance of electromagnetic shielding has become increasingly prominent. Especially in high-tech fields such as modern communication, intelligent devices, and medical devices, electromagnetic shielding has become an indispensable technology. Traditional electromagnetic shielding technologies mainly rely on metal materials such as aluminum and copper, which usually absorb or reflect electromagnetic waves through their conductivity and magnetism. However, these traditional materials have some deficiencies, such as large weight, high thickness requirements, and difficulty in achieving precise control of specific frequencies. With the increasing demand for more efficient and precise electromagnetic control, metasurface technology has emerged.

[0003] A metasurface refers to an artificial microstructure designed on the sub-wavelength scale, usually composed of periodically arranged tiny units (metal or dielectric structure units), and these units can regulate the propagation characteristics of electromagnetic waves through reasonable design. The core feature of the metasurface structure is that it can precisely control the propagation behavior of electromagnetic waves on a scale far lower than the wavelength. By designing the shape, arrangement, and material properties of these microstructures, control of electromagnetic wave refraction, reflection, absorption, and even diffraction can be achieved.

[0004] The principle of metasurface electromagnetic shielding technology is based on the local response of the metasurface to electromagnetic waves. Specifically, when an electromagnetic wave encounters a metasurface, the microstructures of the metasurface will interact with the electromagnetic wave, resulting in changes in the phase, amplitude, and propagation direction of the electromagnetic wave. This effect enables the metasurface to effectively shield electromagnetic waves in specific frequency bands and guide the electromagnetic wave 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, the metasurface can achieve precise regulation of specific frequencies, so it is possible to design highly selective electromagnetic shielding effects for different application scenarios. Second, the metasurface has the characteristics of being thin and light, and can achieve efficient electromagnetic shielding without significantly increasing the volume and weight. In addition, the manufacturing process of metasurface materials is relatively simple and easy for large-scale production, so it has good economic viability and scalability.

[0006] However, the existing metasurface electromagnetic shielding technology needs to achieve polarization conversion and relies on magnetic resonance, and magnetic resonance requires the structure of the metasurface electromagnetic shielding system to be about one-fifth of the wavelength, making it impossible to achieve ultra-thin.

[0007] The above content is only used to assist in understanding the technical solution of the present invention, and does not represent an admission that the above content is prior art. Summary of the Invention

[0008] The main object of the present invention is to provide a metasurface system for realizing electromagnetic shielding and transmission window based on mode coupling, aiming to solve the technical problem in the prior art that the metasurface electromagnetic shielding technology needs to achieve polarization conversion and relies on magnetic resonance, while magnetic resonance requires the structure of the metasurface electromagnetic shielding system to be about one-fifth of the wavelength, making it impossible to achieve ultra-thin.

[0009] To achieve the above object, the present invention provides a metasurface system for realizing electromagnetic shielding and transmission window based on mode coupling. The metasurface system sequentially includes a first metal layer, a dielectric layer, and a second metal layer along the vertical direction.

[0010] The first metal layer, the dielectric layer, and the second metal layer are square structures, and the side lengths are all P, and the heights along the vertical direction are h1, h2, and h3 in sequence.

[0011] The first metal layer is penetrated with a first metal slit extending horizontally. The first metal slit is parallel to the first side of the first metal layer and is symmetrically arranged with respect to the center line of the first side. The second metal layer is penetrated with a second metal slit extending longitudinally. The second metal slit is parallel to the second side of the second metal layer and is symmetrically arranged with respect to the center line of the second side. The first side and the second side are perpendicular to each other. 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 Dlta.

[0012] The heights of the first metal layer, the dielectric layer, and the second metal layer along the vertical direction are 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, both the first metal layer and the second metal layer are 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, according to the frequencies ω of two resonance modess 、 ω a , based on the FDTD metasurface simulation model, obtain a1, a2, and P;

[0017] Step S220: Determine the initial values of Dlta and h2 according to the obtained P, where Dlta ≤ P / 2 and 0.1*P ≤ h2 ≤ P;

[0018] Step S230: Calculate the reflection coefficient r and the transmission coefficient t according to the following formulas (1) to (3);

[0019]

[0020] Step S240: Calculate the shielding effect and the polarization conversion rate according to the reflection coefficient r and the transmission coefficient t; Step S250: Determine whether the shielding effect and the polarization conversion rate meet the preset conditions;

[0021] Step S260: When the judgment result is no, continue to execute Step S220 to enter the next cycle; Step S270: When the judgment result is yes, take the Dlta and h2 determined in Step S220 as the final values; where,

[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, where 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, where 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 between mode a and mode s, and the calculation formula is as follows:

[0030]

[0031] For d 1s Take the complex conjugate;

[0032] For d 2s Take the complex conjugate;

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

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

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

[0036] d 2a Is the coupling coefficient between 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 operating frequency point in the a mode;

[0043] W s Is the operating frequency point in the s mode;

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

[0045] ω is 2πf, and f is the frequency.

[0046] Preferably, in the metasurface system for realizing electromagnetic shielding and transmission window based on mode coupling, in the step S240, the step 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 rate = 1 - |r| 2 .

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

[0050] Step S251 of determining 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 into an M×N array in a two-dimensional plane with a period of 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 realizes electromagnetic shielding and transmission window by normally incident x-polarized electromagnetic waves on the surface of the metasurface system and receiving y-polarized electromagnetic waves at the transmission end of the metasurface system.

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

[0056] The metasurface system provided by the present invention includes, in the vertical direction, a first metal layer, a dielectric layer, and a second metal layer in sequence; the first metal layer, the dielectric layer, and the second metal layer are square structures, and the side lengths are all P, and the heights in the vertical direction are h1, h2, and h3 respectively; the first metal layer is penetrated with a first metal slit extending in the horizontal direction, the first metal slit is arranged parallel to the first side of the first metal layer, and is symmetrically arranged with respect to the center line of the first side; the second metal layer is penetrated with a second metal slit extending in the vertical direction, the second metal slit is arranged parallel to the second side of the second metal layer, and is symmetrically arranged with respect to the center line of the second side; the first side and the second side are perpendicularly arranged, and the distances from the center of the first metal slit to the center of the first metal layer and from the center of the second metal slit to the center of the second metal layer are both Dlta; the heights of the first metal layer, the dielectric layer, and the second metal layer in the vertical direction are h1, h2, and h3 respectively, the length of the first metal slit in the horizontal direction is a2, the width in the vertical direction is a1, and the height in the vertical direction is h1; the length of the second metal slit in the horizontal direction is a1, the width in the vertical direction is a2, and the height in the vertical direction is h3; the relative dielectric constant of the dielectric layer is 3.66, and through artificial microstructures including two resonance modes, electromagnetic shielding and polarization conversion are achieved through the coupling between the modes. By irradiating the metasurface with x-polarized electromagnetic waves, electromagnetic shielding is achieved through the resonance of the artificial microstructures, and polarization conversion is achieved by emitting y-polarized electromagnetic waves, which has the advantages of high efficiency, ultra-thin, etc.

[0057] Further, in the present invention, since two metal slits (the first metal slit and the second metal slit) are provided, and the electric field of the evanescent wave is generated at the first metal slit and the second metal slit, and the evanescent wave will gradually weaken as the distance increases, so the thickness must be limited to ensure that the two evanescent waves generate a near-field coupling with sufficient intensity. For this reason, the thickness of this system is ultra-thin.

[0058] Further, the metasurface system provided by the present invention has nothing to do with magnetic resonance and uses near-field coupling. Therefore, the thickness can be made to be one three-hundred-and-sixtieth of the wavelength, achieving ultra-thin. For example, when the working wavelength is 43 mm, the thickness of the metasurface system is 0.12 mm. Description of the Drawings

[0059] Figure 1 Schematically shows the schematic diagram of the metasurface system provided by the present invention for realizing electromagnetic shielding and transmission window based on mode coupling;

[0060] Figure 2 is Figure 1 the top view of the first metal layer in

[0061] Figure 3 is Figure 1 the top view of the second metal layer in

[0062] Figure 4 Schematically shows a flowchart of a method for determining various parameters in the metasurface system for realizing electromagnetic shielding and transmission window based on mode coupling provided by the present invention;

[0063] Figure 5 Schematically shows a near-field coupling schematic diagram of upper and lower two modes;

[0064] Figure 6 Schematically shows a simulation result diagram of the polarization conversion ratio (PCR) of the metasurface system of the present invention.

[0065] 1 - First metal layer, 11 - First metal slit, 2 - Dielectric layer, 3 - Second metal layer, 31 - Second metal slit.

[0066] The realization of the object, functional features and advantages of the present invention will be further described with reference to the accompanying drawings in combination with embodiments. Detailed implementation manners

[0067] The technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are part of the embodiments of the present invention, rather than all of the embodiments. The present invention will be described in detail below with reference to the accompanying drawings in combination with embodiments. It should be noted that, without conflict, the embodiments in the present invention and the features in the embodiments can be combined with each other.

[0068] In the embodiments of the present invention, the term "and / or" describes the association relationship of associated objects, indicating that three relationships may exist. For example, A and / or B may represent: A exists alone, A and B exist simultaneously, and B exists alone. The character " / " generally represents an "or" relationship between the associated objects before and after.

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

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

[0071] In the present invention, unless otherwise stated, the orientation terms such as "upper, lower, top, bottom" are usually in the direction shown in the accompanying drawings, or in the vertical, perpendicular or gravitational direction of the component itself; similarly, for the convenience of understanding and description, "inner, outer" refer to the inner and outer of the contour of each component itself, but the above orientation terms do not limit the present invention.

[0072] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the embodiments of the present invention will be described in detail below with reference to the accompanying drawings. However, those of ordinary skill in the art can understand that in the embodiments of the present invention, many technical details are provided to help readers better understand the present invention. However, even without these technical details and various changes and modifications based on the following embodiments, the technical solutions claimed in the present invention can still be implemented. The division of the following embodiments is for convenience of description and should not constitute any limitation to the specific implementation of the present invention. The various embodiments can be combined and cross-referenced with each other on 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, to achieve polarization conversion in this three-layer structure, it relies on magnetic resonance, and magnetic resonance requires the three-layer structure to be about one-fifth of the wavelength.

[0074] To solve the above problems, the present invention provides a metasurface system based on mode coupling for electromagnetic shielding and transmission windows, as Figures 1 to 3 shown. 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 lengths are all P, and the heights along the vertical direction are 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 parallel to the first side of the first metal layer 1 and is 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 longitudinal direction. The second metal slit 31 is parallel to the second side of the second metal layer 3 and is symmetrically arranged with respect to the center line of the second side. The first side and the second side are perpendicular to each other. The distances from the center of the first metal slit 11 to the center of the first metal layer 1 and from the center of the second metal slit 31 to the center of the second metal layer 3 are both Dlta. The heights of the first metal layer 1, the dielectric layer 2, and the second metal layer 3 along the vertical direction are h1, h2, and h3 in sequence. The length of the first metal slit 11 along the horizontal direction is a2, the width along the longitudinal 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 longitudinal direction is a2, and the height along the vertical direction is h3. The relative permittivity of the dielectric layer is 3.66.

[0075] The metasurface system provided by the present invention includes a first metal layer 1, a dielectric layer 2, and a second metal layer 3 in sequence along the vertical direction; the first metal layer 1, the dielectric layer 2, and the second metal layer 3 are square structures with side lengths all being P and heights along the vertical direction being h1, h2, and h3 respectively; 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 parallel to the first side of the first metal layer 1 and is 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 longitudinal direction, the second metal slit 31 is arranged parallel to the second side of the second metal layer 3 and is symmetrically arranged with respect to the center line of the second side; the first side and the second side are perpendicular to each other, and the distances from the center of the first metal slit 11 to the center of the first metal layer 1 and from the center of the second metal slit 31 to the center of the second metal layer 3 are both Dlta; the heights of the first metal layer 1, the dielectric layer 2, and the second metal layer 3 along the vertical direction are h1, h2, and h3 respectively, the length of the first metal slit 11 along the horizontal direction is a2, the width along the longitudinal 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 longitudinal direction is a2, and the height along the vertical direction is h3; the relative dielectric constant of the dielectric layer is 3.66. Through artificial microstructures including two resonance modes, electromagnetic shielding and polarization conversion are achieved through the coupling between the modes. By irradiating the metasurface with x-polarized electromagnetic waves, electromagnetic shielding is achieved through the resonance of the artificial microstructures and polarization conversion is achieved by emitting y-polarized electromagnetic waves, having the advantages of high efficiency, ultra-thin, etc.

[0076] The metasurface system provided by the present invention has nothing to do with magnetic resonance and utilizes near-field coupling, so the thickness can be made to be one three-hundred-and-sixtieth of the wavelength, achieving ultra-thin. For example, when the working wavelength is 43 mm, the thickness of the metasurface system is 0.12 mm.

[0077] Furthermore, the metasurface system provided by the present invention is based on the coupling of microstructural resonance modes. Taking the metasurface as a bridge, it can shield electromagnetic waves in an ultra-wideband and realize a transmission window for electromagnetic waves at specific frequencies.

[0078] Furthermore, the metasurface system provided by the present invention is based on mode coupling to achieve electromagnetic shielding and a transmission window. It can not only be used to achieve electromagnetic shielding, but also due to the coupling effect of the modes, the thickness of the device can be made very thin, and finally a deflection conversion effect where the polarization of the transmitted electromagnetic wave is different from that of the incident electromagnetic wave is achieved.

[0079] In some embodiments, both the first metal layer 1 and the second metal layer 3 are 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 metasurface system, the square structure is periodically extended in a two-dimensional plane into an M×N array with a period of P to form an array metasurface. The length (i.e., the x direction) and width (y direction) of the metasurface system correspond to the total length sizes of M and N artificial atoms. In some embodiments, M = 23 artificial atoms and N = 23 artificial atoms. In some other embodiments, M and N can also be set as needed.

[0081] Based on the above metasurface system, an electromagnetic wave with x polarization is normally incident on the surface of the metasurface system, and an electromagnetic wave with y polarization is received at the transmission end of the metasurface system to achieve electromagnetic shielding and a transmission window.

[0082] Among them, the method for determining the parameters in the metasurface system that realizes electromagnetic shielding and a transmission window based on mode coupling is as Figure 4 shown.

[0083] At step S210, according to the frequencies ω s 、ω a of two resonance modes, based on the FDTD metasurface simulation model, a1, a2, and P are obtained.

[0084] It should be noted that the frequencies ω s 、ω a of the two resonance modes can be the frequency points at which one wants to work, and can be specifically determined according to needs. For example, ω s is taken as 7 GHz, and ω a is taken as 8 GHz.

[0085] When the metasurface system includes two resonance modes, s can be taken as 1 and a can be taken as 2, that is, one mode is the frequency ω s , and the other mode is ω a . Since there are a total of two modes for s and a, the metasurface system is defaulted to have two ports. The metasurface system has two external ports and two resonance modes.

[0086] Inputting the frequencies ω s 、ω a into the FDTD (Finite-Difference Time-Domain) metasurface simulation model, a1, a2, and P can be obtained. In order to efficiently achieve electromagnetic shielding and polarization effects, the artificial microstructures of the metasurface system adopt metal slits with a relatively narrow opening. Based on the FDTD metasurface simulation model, a beam of x-polarized electromagnetic wave is simulated to be incident on the designed artificial microstructures, and only an electromagnetic wave with y polarization exists in the transmitted light.

[0087] At step S220, initial values of Dlta and h2 are determined based on the obtained P, where Dlta ≤ P / 2 and 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] where,

[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 symbol 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 mode a and mode s, and the calculation formula is 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 between the first port and the sth mode;

[0103] d 1a is the coupling coefficient between the first port and the ath mode;

[0104] d 2s is the coupling coefficient between the second port and the sth mode;

[0105] d 2a is the coupling coefficient between the second port and the ath 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 operating frequency point in the a mode;

[0112] W s is the operating frequency point in the s mode;

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

[0114] ω is 2πf, and f is the frequency.

[0115] It should be noted that after a1, a2, Dlta, and h2 are determined, the above d 1s , d 1a , d 2s , d 2a , as well as Γ s , Γ′ s , Γ a , Γ′ a and other specific values can be obtained through the FDTD metasurface simulation model, so X is also determined accordingly. Therefore, the above parameters are determined. According to the above formulas, r and t can be calculated.

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

[0117] Among them, shielding effect = 20 * log 10 (|t|);

[0118] 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 conditions.

[0120] Among them, the preset conditions can but are not limited to including that the shielding effect is greater than or equal to -20 dB and the polarization conversion rate is greater than or equal to 80%. Specifically, in 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 negative, step S220 is continued to enter the next cycle. Among them, when the shielding effect and the polarization conversion rate do not meet the preset conditions, step S220 is entered to reselect Dlta and h2, and then steps S230 to S250 are continued until the judgment result is positive.

[0122] At step S270, when the judgment result is positive, Dlta and h2 determined in step S220 are used as the final values.

[0123] Figure 5 Schematically shows the near-field coupling schematic diagrams of the upper and lower two modes. Figure 6 Schematically shows the simulation result diagram of the polarization conversion rate (PCR) of the metasurface system of the present invention. As Figure 5 and Figure 6 It can be seen that within the working band, the polarization conversion efficiency of the two transmission peaks both reaches more than 99%, and the average shielding effect is -36 dB, indicating that the metasurface system designed by the present invention not only has a strong electromagnetic shielding effect, but also has a high polarization conversion effect. When the working wavelength of the metasurface system designed by the present invention 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-hundred-and-sixtieth of the working wavelength.

[0124] Obviously, the above-described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, those of ordinary skill in the art can make other different forms of changes or modifications without creative efforts, and all should belong to the protection scope of the present invention.

Claims

1. A metasurface system for realizing electromagnetic shielding and transmission window based on mode coupling, characterized in that The metasurface system sequentially includes a first metal layer, a dielectric layer, and a second metal layer in the vertical direction; The first metal layer, the dielectric layer, and the second metal layer are square structures, and the side lengths are all P, and the heights in the vertical direction are h1, h2, and h3 in sequence; The first metal layer is penetrated with a first metal slit extending in the horizontal direction. The first metal slit is arranged parallel to the first side of the first metal layer and is symmetrically arranged with respect to the center line of the first side; the second metal layer is penetrated with a second metal slit extending in the longitudinal direction. The second metal slit is arranged parallel to the second side of the second metal layer and is symmetrically arranged with respect to the center line of the second side; the first side and the second side are perpendicularly arranged, and the distances from the center of the first metal slit to the center of the first metal layer and from the center of the second metal slit to the center of the second metal layer are both Dlta; The heights of the first metal layer, the dielectric layer, and the second metal layer in the vertical direction are h1, h2, and h3 in sequence. The length of the first metal slit in the horizontal direction is a2, the width in the longitudinal direction is a1, and the height in the vertical direction is h1; the length of the second metal slit in the horizontal direction is a1, the width in the longitudinal direction is a2, and the height in the vertical direction is h3; The relative dielectric constant of the dielectric layer is 3.

66.

2. The metasurface system for realizing electromagnetic shielding and transmission window based on mode coupling as claimed in claim 1, wherein Both the first metal layer and the second metal layer are copper layers.

3. The metasurface system for realizing electromagnetic shielding and transmission window based on mode coupling according to claim 1, characterized in that The method for determining the parameters in the metasurface system for realizing electromagnetic shielding and transmission window based on mode coupling is as follows: Step S210, according to the frequencies ω s and ω a , based on the FDTD metasurface simulation model, obtain a1, a2, and P; Step S220, according to the obtained P, determine the initial values of Dlta and h2, where Dlta ≤ P / 2 and 0.1*P ≤ h2 ≤ P; Step S230, calculate the reflection coefficient r and the transmission coefficient t according to the following formulas (1) to (3); Step S240, calculate the shielding effect and the polarization conversion rate according to the reflection coefficient r and the transmission coefficient t; Step S250, judge whether the shielding effect and the polarization conversion rate meet the preset conditions; Step S260, when the judgment result is no, continue to execute step S220 to enter the next round of loop; Step S270, when the judgment result is yes, take Dlta and h2 determined in step S220 as the final values; Wherein, ψ s is the amplitude of the s-th resonant mode in the system; Ψ a is the amplitude of the a-th resonant mode in the system; i is the imaginary symbol in mathematics; Γ s is the radiation damping for the s-th mode, where 2Γ s = |d 1s | 2 + |d 2s | 2 ; Γ′ s is the absorption damping for the s-th mode; Γ a is the radiation damping of the a-th mode, where 2Γ a = |d 1a | 2 + |d 2a | 2 ; Γ′ a is the absorption damping for the a-th mode; X is the far-field coupling strength of mode a and mode s, and the calculation formula is as follows: For d 1s Take the complex conjugate; For d 2s Take the complex conjugate; d 1s is the coupling coefficient between the first port and the s-th mode; d 1a is the coupling coefficient between the first port and the a-th mode; d 2s is the coupling coefficient between the second port and the s-th mode; d 2a is the coupling coefficient between the second port and the a-th mode; 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, taking -1; t0 is a constant, taking 0; W a is the operating frequency point in mode a; W s is the operating frequency point in s mode; W i = i(ω - ω i ) + Γ i + Γ′ v , i = s, a; ω is 2πf, and f is the frequency.

4. The metasurface system for realizing electromagnetic shielding and transmission window based on mode coupling according to claim 3, wherein In step S240, in the step 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: Shielding effect = 20 * log 10 (|t|); Polarization conversion rate = 1 - |r| 2 .

5. The metasurface system for realizing electromagnetic shielding and transmission window based on mode coupling according to claim 3, characterized in that In step S250, judging whether the shielding effect and the polarization conversion rate meet the preset conditions includes: Step S251, judge 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 for realizing electromagnetic shielding and transmission window based on mode coupling according to claim 1, wherein The metasurface system has two external ports and two resonance modes.

7. The metasurface system for realizing electromagnetic shielding and transmission window based on mode coupling according to claim 1, wherein Periodically extend the square structure in the two-dimensional plane into an M×N array with a period of P to form an array metasurface.

8. The metasurface system for realizing electromagnetic shielding and transmission window based on mode coupling according to claim 7, wherein M = 23 artificial atoms, N = 23 artificial atoms.

9. The metasurface system for realizing electromagnetic shielding and transmission window based on mode coupling according to claim 1, characterized in that, The metasurface system realizes electromagnetic shielding and a transmission window by normally incident electromagnetic waves with x polarization on the surface of the metasurface system and receiving electromagnetic waves with y polarization at the transmission end of the metasurface system.

10. The metasurface system for realizing electromagnetic shielding and transmission window based on mode coupling according to claim 1, characterized in that, When the working wavelength is 43 mm, the thickness of the metasurface system is 0.12 mm.

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