A high-transparency metal mesh electromagnetic protection device based on periodic shielding and periodic wave absorption and a parameter optimization method thereof

Abstract

The application discloses a high-transparency metal mesh electromagnetic protection device based on periodic shielding and periodic wave absorption and a parameter optimization method thereof, wherein a transparent medium layer is arranged between a top metal mesh layer and a bottom metal mesh layer, the top metal mesh layer is used for reducing electromagnetic wave reflection, the bottom metal mesh layer is used for shielding electromagnetic waves, and the transparent medium layer reflects electromagnetic waves multiple times to cause electromagnetic wave loss. When designing, metal mesh electromagnetic protection device parameters are set according to requirements, and modeling simulation is carried out by using simulation software; based on the simulation result, the device structure parameters are optimized until the electromagnetic protection and light transmission effects meet the design requirements. The application makes it possible to reduce the transmission as much as possible, increase the structure wave absorption performance, match the periodic wave absorption performance curve of the top metal mesh layer with the periodic shielding performance curve of the bottom metal mesh layer, and complement each other to realize periodic complementation of electromagnetic wave absorption and shielding.

Description

Technical Field

[0001] This invention belongs to the field of electromagnetic protection, specifically relating to a high-transmittance metal mesh electromagnetic protection device based on periodic shielding and periodic absorption, and a method for optimizing its parameters. Background Technology

[0002] Electromagnetic protection is the prevention of electromagnetic interference generated by electronic equipment by isolating it from external electromagnetic waves. Electromagnetic protection is typically achieved using electromagnetic shielding materials, which can be broadly classified into shielding materials and absorbing materials. Electromagnetic wave shielding materials are those that strongly reflect incident electromagnetic waves. Electromagnetic wave absorbing materials are those that absorb and attenuate incident electromagnetic waves, converting their electromagnetic energy into heat energy for dissipation or causing the electromagnetic waves to disappear due to interference. For transparent windows, not only must the electromagnetic shielding material meet the required performance, but additional conditions regarding transparency and light transmittance must also be met.

[0003] Electromagnetic metamaterials are generally used to design electromagnetic shielding structures. These materials can effectively control the propagation mode, polarization, and wavefront of electromagnetic waves, and are currently widely used in the design of absorbers, electromagnetic shielding, and polarization converters. However, practical electromagnetic shielding requires addressing several challenges in actual design: 1) The presence of thick media causes periodic oscillations in the transmission and reflection spectra, affecting the material's broadband shielding performance. 2) For applications in transparent windows, especially when placed inside the window, it is necessary not only to minimize transmission but also to achieve high light transmittance of the electromagnetic shielding material. Summary of the Invention

[0004] To address the aforementioned problems, the present invention aims to provide a high-transmittance metal mesh electromagnetic protection device and its parameter optimization method based on periodic shielding and periodic absorption. Utilizing a double-layer metal mesh structure, it simultaneously possesses electromagnetic properties of periodic absorption and periodic shielding, achieving a shielding effectiveness greater than 10dB, an absorption rate of 0.9, and a transmittance of 98% in the (1-18) GHz range.

[0005] The specific technical solution for achieving the objective of this invention is as follows:

[0006] A high-transmittance metal mesh electromagnetic protection device based on periodic shielding and periodic wave absorption includes a top metal mesh layer, a transparent dielectric layer, and a bottom metal mesh layer.

[0007] The transparent dielectric layer is disposed between the top metal mesh layer and the bottom metal mesh layer;

[0008] The top metal mesh layer is used to absorb electromagnetic waves and reduce electromagnetic wave reflection, the bottom metal mesh layer is used to shield electromagnetic waves, and the transparent dielectric layer reflects electromagnetic waves multiple times, thereby causing electromagnetic wave loss.

[0009] Furthermore, the mesh structure of the top metal mesh layer and the bottom metal mesh layer includes, but is not limited to, a cross mesh structure, a hexagonal mesh structure, a right-angled triangle mesh structure, or an equilateral triangle mesh structure.

[0010] Furthermore, the transparent medium layer is a highly transparent material, including but not limited to glass, polyethylene terephthalate, and zinc sulfide.

[0011] Furthermore, the transmittance and reflection coefficient of the transparent dielectric layer oscillates periodically with the frequency of the target electromagnetic wave.

[0012] Furthermore, the absorption efficiency curve of the top metal mesh layer and the shielding efficiency curve of the bottom metal mesh layer both exhibit periodic oscillations.

[0013] Furthermore, the peaks of the periodic absorption efficiency curve and the periodic shielding efficiency curve are complementary and staggered.

[0014] Furthermore, the top metal mesh layer and the bottom metal mesh layer have the same structure, which is a cross-shaped mesh structure;

[0015] The transparent medium layer is made of plexiglass and has a thickness of 15mm.

[0016] Furthermore, the cross-shaped mesh structure has a line width of 5μm, a period of 200μm, a line resistance of 20Ω for the top metal mesh layer, and a line resistance of 0.2Ω for the top metal mesh layer.

[0017] Furthermore, the parameter optimization method based on any of the above devices includes the following steps:

[0018] Step 1: Set the structure, linewidth, period, and line-to-surface resistance of the top and bottom metal mesh layers according to requirements;

[0019] Step 2: Set the dielectric material and thickness of the transparent dielectric layer according to requirements;

[0020] Step 3: Based on the device structural parameters set in Step 1 and Step 2, perform modeling and simulation using CST full-wave simulation software;

[0021] Step 4: Optimize the parameters of the device structure based on the simulation results until the electromagnetic protection and light transmission effects of the design are met.

[0022] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0023] (1) The technical solution of the present invention proposes a high-transmittance metal mesh electromagnetic protection structure device based on periodic shielding and periodic absorption, which has the electromagnetic properties of periodic absorption and periodic shielding, so as to achieve the minimum transmission while increasing the absorption performance.

[0024] (2) The present invention uses a double-layer metal mesh structure design to reduce transmission as much as possible while increasing the structural wave absorption performance. At the same time, the periodic wave absorption efficiency curve of the top metal mesh layer matches the peak-valley of the periodic shielding efficiency curve of the bottom metal mesh layer. The two complement each other to achieve periodic complementarity of electromagnetic wave absorption and shielding. Attached Figure Description

[0025] Figure 1 This is a schematic diagram of the high-transmittance metal mesh electromagnetic protection device of the present invention.

[0026] Figure 2 This is a schematic diagram of different metal mesh structures in the high-transmittance metal mesh electromagnetic protection device in an embodiment of the present invention.

[0027] Figure 3 Schematic diagrams of cross-shaped metal mesh and single-layer cross-shaped metal mesh with a transparent dielectric layer.

[0028] Figure 4 This is a schematic diagram of the transparent dielectric layer in the high-transmittance metal mesh electromagnetic protection device in an embodiment of the present invention.

[0029] Figures 5-8 This is a simulation diagram of the transmission and reflection spectrum oscillation under different conditions in the embodiments of the present invention.

[0030] Figure 9 This is a schematic diagram of the transmission and reflection coefficient curves of the high-transmittance metal mesh electromagnetic protection device in an embodiment of the present invention, showing the periodic shielding and periodic absorption. Detailed Implementation

[0031] A high-transmittance metal mesh electromagnetic protection device based on periodic shielding and periodic wave absorption includes a top metal mesh layer, a transparent dielectric layer, and a bottom metal mesh layer.

[0032] The transparent dielectric layer is disposed between the top metal mesh layer and the bottom metal mesh layer;

[0033] The top metal mesh layer absorbs electromagnetic waves and reduces their reflection, while the bottom metal mesh layer shields them. The transparent dielectric layer reflects electromagnetic waves multiple times, causing them to be attenuated. This achieves a metasurface structure that simultaneously possesses periodic shielding and periodic absorption properties, enabling high transmittance while absorbing incident electromagnetic waves, thus increasing absorption performance and achieving electromagnetic protection.

[0034] Furthermore, the mesh structures of the top metal mesh layer and the bottom metal mesh layer can be the same or different, including but not limited to cross mesh structures, hexagonal mesh structures, right-angled triangle mesh structures or equilateral triangle mesh structures.

[0035] Furthermore, the material of the transparent dielectric layer is plexiglass, indium tin oxide (ITO) or fluorine-doped tin oxide (FTO), polyethylene terephthalate, zinc sulfide, etc.

[0036] The transmittance and reflection coefficient of the transparent dielectric layer oscillates periodically with the frequency of the target electromagnetic wave, and the absorption efficiency curve of the top metal mesh layer and the shielding efficiency curve of the bottom metal mesh layer both exhibit periodic oscillations.

[0037] Furthermore, the peaks of the periodic absorption efficiency curve and the periodic shielding efficiency curve are complementary and staggered.

[0038] Furthermore, since the electromagnetic protection structure is placed in the optical window interlayer, a certain dielectric thickness and a high light transmittance are required. However, the increase in dielectric thickness will cause periodic oscillations in the shielding effectiveness curve and the absorption effectiveness curve within the frequency band. Therefore, in this scheme, the periodic absorption effectiveness curve of the top metal mesh layer and the periodic shielding effectiveness curve of the bottom metal mesh layer are matched with peak-trough, and the shielding performance and absorption performance work alternately to achieve full-band electromagnetic protection function.

[0039] Furthermore, the top metal mesh layer and the bottom metal mesh layer have the same structure, which is a cross-shaped mesh structure;

[0040] The transparent medium layer is made of plexiglass and has a thickness of 15mm.

[0041] Furthermore, the cross-shaped mesh structure has a line width of 5μm, a period of 200μm, a line resistance of 20Ω for the top metal mesh layer, and a line resistance of 0.2Ω for the top metal mesh layer.

[0042] The parameter optimization method based on the above device includes the following steps:

[0043] Step 1: Set the structure, linewidth, period, and line-to-surface resistance of the top and bottom metal mesh layers according to requirements. The top and bottom metal mesh structures can be different or the same. The shape, linewidth, and period of the metal mesh structure directly affect the light transmittance of the structure; the line-to-surface resistance affects the shielding effectiveness of the mesh structure; at the same time, different metal mesh structures will have different electromagnetic shielding effectiveness due to their duty cycle and current path.

[0044] Generally, the first consideration is the light transmittance of the structure. This condition strictly limits the line width and period of the metal mesh structure. The metal mesh structure must be designed under the premise of satisfying the light transmittance of the structure.

[0045] Step 2: Determine the dielectric material and thickness of the transparent dielectric layer according to requirements. The dielectric material directly affects the transparency and light transmittance of the structure, and the different dielectric constants of different materials will also affect the final stealth effect. The thickness of the dielectric can effectively improve the electromagnetic shielding effect, but at the same time, it will reduce the light transmittance of the structure.

[0046] Step 3: Based on the device structure parameters set in Step 1 and Step 2, use CST full-wave simulation software to perform modeling and simulation. In CST, model the overall structure, match the parameters, use time-domain simulation, select the target frequency band, and obtain the reflectivity parameter S11, transmittance parameter S21, and other parameters of the designed structure in the target frequency band. This allows for further analysis of its wave absorption and shielding performance.

[0047] Step 4: Optimize the parameters of the device structure based on the simulation results until the electromagnetic protection and light transmission effects of the design are met. That is, the absorption performance and shielding performance of the designed structure are optimized in reverse to meet the electromagnetic protection performance.

[0048] The present invention will be further described below with reference to the embodiments.

[0049] Example

[0050] Combination Figure 1 A high-transmittance metal mesh electromagnetic protection device based on periodic shielding and periodic wave absorption, comprising a top metal mesh layer, a transparent dielectric layer and a bottom metal mesh layer;

[0051] The transparent dielectric layer is disposed between the top metal mesh layer and the bottom metal mesh layer;

[0052] The top metal mesh layer absorbs electromagnetic waves and reduces their reflection, while the bottom metal mesh layer shields them. The transparent dielectric layer reflects electromagnetic waves multiple times, causing them to be attenuated. This achieves a metasurface structure that simultaneously possesses periodic shielding and periodic absorption properties, enabling high transmittance while absorbing incident electromagnetic waves, thus increasing absorption performance and achieving electromagnetic protection.

[0053] First, the top layer and coating metal mesh structures were determined. While ensuring a visible light transmittance of 99% for both, [the following steps were taken]. Figure 2 Simulation analysis was performed on four different shapes of periodic metal mesh structures: cross mesh, hexagonal mesh, right-angled triangular mesh, and equilateral triangular mesh.

[0054] First, the shielding effectiveness of four different metal mesh structures under different polarization conditions was analyzed. Simulations were performed with polarization angles ranging from 0° to 360° and a step size of 15° to obtain the minimum shielding effectiveness of the four different metal mesh shapes under different polarization angles, as shown in the table below:

[0055]

[0056] The shielding effectiveness is as follows: equilateral triangular mesh > cross mesh > hexagonal mesh > right-angled triangular mesh. Taking into account the fabrication process, the metal mesh layer structure in this embodiment is finally determined to be a cross-shaped mesh structure.

[0057] Secondly, the material and thickness of the transparent dielectric layer are determined. Due to the requirement of light transmittance, in this embodiment, plexiglass is selected as the dielectric layer material, with a dielectric constant of 7 to 8.5.

[0058] Combination Figure 3 The simulation was conducted with a cross-shaped metal mesh without dielectric (i.e., dielectric thickness of 0) and with dielectrics of different thicknesses. A single-layer metal mesh was placed outside the dielectric. A periodic structure simulation was set up, and the S21 curve, i.e. the shielding effectiveness curve, was observed. The periodic oscillation was caused by the high dielectric constant and the dielectric thickness. As the dielectric thickness increased, the oscillation period of the shielding effectiveness curve increased. The overall oscillation trend was consistent, oscillating along the curve without dielectric, and the minimum value of SE decreased. The line width affected the oscillation trend and affected SEmin. The line surface resistance affected the overall size of SE, and the duty cycle affected the oscillation amplitude.

[0059] Under four conditions—a fixed dielectric constant of 8, line-to-surface resistance Rs = 0.1, linewidth w = 1 μm, and transmittance of 98%; ② a fixed dielectric constant of 8, line-to-surface resistance Rs = 0.1, linewidth w = 7 μm, and transmittance of 98%; ③ a fixed dielectric constant of 8, line-to-surface resistance Rs = 0.1, linewidth w = 7 μm, and transmittance of 95%; and ④ a fixed dielectric constant of 8, line-to-surface resistance Rs = 0.3, linewidth w = 7 μm, and transmittance of 95%—the dielectric thickness was varied to 0 mm, 5 mm, 15 mm, 35 mm, and 50 mm. It can be observed that the linewidth affects the oscillation trend and Semin, the duty cycle affects the oscillation amplitude, and the line-to-surface resistance affects the overall SE magnitude. Figure 5-8 As shown.

[0060] Two metal mesh structures with different surface resistivity are designed on the upper and lower surfaces of a glass with a thickness h = 15 mm and a dielectric constant of 8.5. The linewidth is w, the period is p, the surface resistivity of the top mesh is Rs1 (serving as an absorbing layer), and the surface resistivity of the bottom mesh is Rs2 (serving as a shielding layer). The simulation-optimized geometric parameters are shown in the table below, and their transmission and reflection coefficients are as follows: Figure 9As shown, the shielding effectiveness is greater than 10dB in the (1-18) GHz range. The frequency band reflected by the dark black dashed box shows absorption with an absorption rate of approximately 0.9, while the frequency band transmitted by the light black dashed box shows a shielding effectiveness of approximately -15dB. The peak-trough matching of the shielding and absorption effectiveness oscillation curves, with the shielding and absorption performance alternating, achieves full-band electromagnetic protection. This results in a periodic absorption + periodic shielding effect.

[0061] 1 200 20 0.2

[0062] The above embodiments illustrate and describe the basic principles and main features 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 present invention without departing from its spirit and scope, and all such changes and modifications fall within the scope of the present invention as claimed.

Claims

1. A high-transmittance metal mesh electromagnetic protection device based on periodic shielding and periodic wave absorption, characterized in that, It includes a top metal mesh layer, a transparent dielectric layer, and a bottom metal mesh layer; The transparent dielectric layer is disposed between the top metal mesh layer and the bottom metal mesh layer; The top metal mesh layer is used to absorb electromagnetic waves and reduce electromagnetic wave reflection, the bottom metal mesh layer is used to shield electromagnetic waves, and the transparent dielectric layer reflects electromagnetic waves multiple times, thereby causing electromagnetic wave loss. The transmittance and reflection coefficient of the transparent dielectric layer oscillates periodically with the frequency of the target electromagnetic wave; Both the absorption efficiency curve of the top metal mesh layer and the shielding efficiency curve of the bottom metal mesh layer exhibit periodic oscillations. Furthermore, the peaks of the periodic absorption efficiency curve and the periodic shielding efficiency curve are complementary and staggered. The top metal mesh layer and the bottom metal mesh layer have the same structure, which is a cross-shaped mesh structure; The transparent medium layer is made of plexiglass and has a thickness of 15mm.

2. The high-transmittance metal mesh electromagnetic protection device based on periodic shielding and periodic absorption according to claim 1, characterized in that, The mesh structures of the top and bottom metal mesh layers include, but are not limited to, cross mesh structures, hexagonal mesh structures, right-angled triangular mesh structures, or equilateral triangular mesh structures.

3. The high-transmittance metal mesh electromagnetic protection device based on periodic shielding and periodic absorption according to claim 1, characterized in that, The transparent medium layer is a highly transparent material, including but not limited to glass, polyethylene terephthalate, and zinc sulfide.

4. The high-transmittance metal mesh electromagnetic protection device based on periodic shielding and periodic absorption according to claim 1, characterized in that, The cross-shaped mesh structure has a line width of 5μm, a period of 200μm, a surface resistance of 20Ω for the top metal mesh layer, and a surface resistance of 0.2Ω for the bottom metal mesh layer.

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