An efficient method for acquiring low-frequency transmission characteristics of a multi-layer metal mesh model based on FDTD

Abstract

The present invention discloses a method for efficiently acquiring low-frequency transmission characteristics of a multi-layer metal mesh model based on FDTD, including: obtaining the shielding effectiveness of the multi-layer metal mesh; obtaining the polarizability function of the multi-layer metal mesh equivalent dispersion model; obtaining the circular convolution-finite difference time domain formula for calculating the transmission characteristics of the multi-layer metal mesh; using genetic algorithm and shielding effectiveness to invert the electromagnetic parameters of the single-layer equivalent medium to obtain the polarizability parameter K for constructing the polarizability function; using the circular convolution-finite difference time domain formula and the polarizability parameter K to obtain the transmission characteristics of the model containing the multi-layer metal mesh. The method of the present invention greatly improves the calculation efficiency and reduces the consumption of resources while ensuring the calculation accuracy.

Description

Technical Field

[0001] The invention belongs to the technical field of electromagnetic transmission characteristic calculation, and in particular relates to a method for efficiently acquiring low-frequency transmission characteristics of a multi-layer metal mesh model based on FDTD. Background Art

[0002] Metal mesh has important applications in practical engineering, such as metal mesh installed at ventilation duct openings and drainage outlets, steel mesh structures laid on the upper layer of tunnels, microstrip patch antennas with metal mesh films, etc. The diameter of the metal mesh is very different from the overall size of the target, which brings challenges to electromagnetic calculations. Studies have shown that infinite metal mesh can be uniformly equivalent to achieve the purpose of simplifying calculations. The use of equivalent methods can reasonably simplify the model and improve calculation efficiency, avoid multi-scale modeling, and is an important method in electromagnetic calculations.

[0003] The equivalent method uses a single-layer medium to replace the metal mesh structure. There are two methods to calculate the equivalent electromagnetic parameters: ① Use a simple uniform medium instead. Directly measure through experiments, and then perform electromagnetic parameter inversion. The calculation results of this method are too rough and differ greatly from the actual results. ② Based on the geometric dimensions of the metal mesh, the equivalent impedance formula of the equivalent medium is given. Although this method is more cumbersome, the calculation results are very close to the actual results.

[0004] At present, in-depth research has been conducted on the equivalence of two-dimensional infinite metal meshes at home and abroad. In 1988, Casey KF established a thin plate impedance model based on the mean field theory and calculated the reflection coefficient and transmission coefficient of the plane metal mesh. However, this model cannot accurately calculate the situation where the wire diameter is equivalent to the wire spacing, or even the diameter is larger. In 2016, Hyun SY et al. corrected the wire diameter and wire spacing (metal mesh size) of the metal mesh in the Casey KF model, so that the dense metal mesh has better calculation accuracy at the same frequency. However, the calculation results of the shielding effectiveness of the double-layer metal mesh are not accurate. In 2022, Sun Xiangang et al. proposed a new broadband analytical model that can be used for the analysis of the shielding performance of multi-layer metal mesh based on the Hyun analytical model of single-layer metal mesh impedance and the multi-layer conductor shielding theory. The results of the double-layer metal mesh calculated using this analytical model are in good agreement with the simulation results of commercial software using fine meshes.

[0005] For the calculation of shielding effectiveness of multi-layer metal mesh structures, due to the large difference between the metal diameter and the size of large models, the traditional numerical method requires a large number of fine grids to solve related problems, which will lead to a significant increase in the amount of grid calculation, resulting in excessive calculation or calculation failure. It is difficult to conduct numerical simulation research on large models containing metal mesh. Summary of the invention

[0006] In order to solve the above problems existing in the prior art, the present invention provides a method for efficiently acquiring low-frequency transmission characteristics of a multi-layer metal mesh model based on FDTD. The technical problem to be solved by the present invention is achieved through the following technical solutions:

[0007] One aspect of the present invention provides a method for efficiently acquiring low-frequency transmission characteristics of a multi-layer metal mesh model based on FDTD, comprising:

[0008] S1: Obtain the shielding effectiveness of multi-layer metal mesh;

[0009] S2: Obtain the polarizability function of the multilayer metal mesh equivalent dispersion model;

[0010] S3: Obtain the circular convolution-finite difference time domain formula for calculating the transmission characteristics of the multi-layer metal mesh;

[0011] S4: using a genetic algorithm and the shielding effectiveness to invert the electromagnetic parameters of a single-layer equivalent medium, and obtaining a polarizability parameter K for constructing a polarizability function;

[0012] S5: using the circular convolution-finite difference time-domain formula and the polarizability parameter K to obtain the transmission characteristics of the model containing the multi-layer metal mesh.

[0013] In one embodiment of the present invention, the multilayer metal mesh comprises n layers of metal mesh of the same material and thickness, and an air interlayer is formed between two metal layers, wherein the first, third, ..., 2n-1 layers are metal meshes, and the second, fourth, ..., 2n-2 layers are air interlayers;

[0014] The analytical model of the shielding effectiveness of the multi-layer metal mesh is:

[0015] SE n层,网 =(R 1 +R 3 +…+R 2n-1 )+(M 2 +M 4 +…+M 2n-2 ),

[0016] Among them, SE n层,网 It represents the shielding effectiveness of n-layer metal mesh, n represents the number of layers of metal mesh, R 2n-1 represents the reflection loss of the 2n-1th layer of metal mesh, M 2n-2 Represents the multiple reflection loss of the 2n-2th air interlayer.

[0017] In one embodiment of the present invention, the metal mesh polarizability function expression of the equivalent dispersion model is:

[0018] χ(ω)=Kω,

[0019] Among them, ω is the electromagnetic frequency and K is the polarizability parameter.

[0020] In one embodiment of the present invention, S3 includes:

[0021] S3.1: Obtain the discretized form of the Maxwell curl of a linear isotropic medium in the lossless case:

[0022]

[0023] Where E, H, and D represent the electric field intensity, magnetic field intensity, and electric flux density, respectively; Δt is the time interval; and μ represents the magnetic permeability coefficient. represents the Hamiltonian operator;

[0024] S3.2: Obtain the frequency domain constitutive relation of the dispersive medium of the equivalent dispersion model:

[0025] D(ω)=ε 0 E(ω)+ε 0 χ(ω)·E(ω),

[0026] Among them, ε 0 is the vacuum dielectric constant, χ(ω) is the metal mesh polarizability function;

[0027] S3.3: Perform Fourier transform on the frequency domain constitutive relation to obtain the Fourier transformed expression:

[0028]

[0029] Where t represents time, τ represents the integral variable, D(t) represents the electric flux density in the time domain, and E(t) represents the electric field intensity in the time domain;

[0030] S3.4: After obtaining the discretization, the step formula of D→E of the dispersive medium in the discrete time domain is:

[0031]

[0032] Among them, ε ∞ is the relative dielectric constant when the frequency is infinite, Δχ m represents the rate of change of the polarizability function of the metal mesh, χ 0 is the 0th polarizability function;

[0033] S3.5: Introducing auxiliary variables The step formula of D→E is converted to form the circular convolution-finite difference time domain formula:

[0034]

[0035] In one embodiment of the present invention, after S3.5, the following steps are further included:

[0036] Get the χ corresponding to the multilayer metal mesh equivalent dispersion model 0 , Δχ m and the auxiliary variable ψ n The specific expression of .

[0037] In one embodiment of the present invention, the χ corresponding to the multilayer metal mesh equivalent dispersion model is obtained. 0 , Δχ m and the auxiliary variable ψ n The specific expressions include:

[0038] The polarizability function χ(ω)=Kω is subjected to Fourier transformation to obtain:

[0039]

[0040] Then 0 =KΔt 3 / 3π、Δχ m = x m -x m+1 =-2K(m+1)Δt 3 / π;

[0041] Introducing auxiliary variables Then the auxiliary variable ψ n It is expressed as:

[0042]

[0043] In one embodiment of the present invention, the S4 includes:

[0044] S4.1: Generate a random number as parameter K through a binary string;

[0045] S4.2: Utilizing the parameter K and the above, a circular convolution-finite difference time domain formula is formed to calculate the shielding effectiveness of a single-layer equivalent medium, and calculating the error with the shielding effectiveness obtained in step S1;

[0046] S4.3: Repeat steps S4.1 and S4.2, and determine whether the error is less than 10 -4 If the conditions are met, the process ends and the final polarizability parameter K value is obtained.

[0047] Another aspect of the present invention provides a storage medium storing a computer program for executing the steps of the method for efficiently acquiring low-frequency transmission characteristics of a multi-layer metal mesh model based on FDTD as described in any one of the above embodiments.

[0048] Another aspect of the present invention provides an electronic device, including a memory and a processor, wherein the memory stores a computer program, and when the processor calls the computer program in the memory, it implements the steps of the method for efficiently acquiring low-frequency transmission characteristics of a multi-layer metal mesh model based on FDTD as described in any of the above embodiments.

[0049] Compared with the prior art, the present invention has the following beneficial effects:

[0050] 1. The analysis of transmission characteristics of multi-layer metal mesh structures often requires the establishment of a model containing fine structures for numerical calculation, which often consumes a lot of memory and computing time. The FDTD-based efficient acquisition method of low-frequency transmission characteristics of a multi-layer metal mesh model proposed in the present invention can use a larger metal grid to calculate a large-scale model containing a metal mesh, which greatly improves the calculation efficiency and reduces the consumption of resources while ensuring the calculation accuracy.

[0051] 2. The present invention proposes a dispersion model for the shielding effectiveness of multi-layer metal meshes, which can well describe the law of the transmission effectiveness of multi-layer metal meshes. The present invention provides a new idea for calculating the transmission effectiveness of large models containing multi-layer metal meshes.

[0052] The present invention will be further described in detail below with reference to the accompanying drawings and embodiments. BRIEF DESCRIPTION OF THE DRAWINGS

[0053] Figure 1 It is a flow chart of a method for efficiently acquiring low-frequency transmission characteristics of a multi-layer metal mesh model based on FDTD provided by an embodiment of the present invention;

[0054] Figure 2 These are several dispersive medium models provided by the embodiments of the present invention;

[0055] Figure 3 is a schematic diagram of an incident pulse provided by an embodiment of the present invention;

[0056] Figure 4 It is the transmission waveform and shielding effectiveness diagram of a single-layer metal mesh obtained by different methods;

[0057] Figure 5 It is the transmission waveform and shielding effectiveness diagram of double-layer metal mesh obtained by different methods;

[0058] Figure 6 It is a three-dimensional shielding effectiveness diagram of three-layer metal mesh and four-layer metal mesh obtained by different methods;

[0059] Figure 7 is a schematic diagram of an equivalent model of a dielectric cavity with a metal mesh provided by an embodiment of the present invention;

[0060] Figure 8 It is the shielding effectiveness diagram at the midpoint of the three-dimensional model of different layers of metal mesh obtained by different methods;

[0061] Fig. 9 It is a shielding effectiveness diagram of different layers of metal mesh at 450mm below the midpoint of the three-dimensional model obtained by different methods. DETAILED DESCRIPTION

[0062] In order to further illustrate the technical means and effects adopted by the present invention to achieve the predetermined purpose of the invention, the following is a detailed description of the method for efficiently acquiring the low-frequency transmission characteristics of the multi-layer metal mesh model based on FDTD proposed by the present invention in combination with the accompanying drawings and specific implementation methods.

[0063] The above and other technical contents, features and effects of the present invention are clearly presented in the following detailed description of the specific implementation modes in conjunction with the accompanying drawings. Through the description of the specific implementation modes, the technical means and effects adopted by the present invention to achieve the predetermined purpose can be more deeply and specifically understood. However, the attached drawings are only for reference and explanation purposes and are not used to limit the technical solutions of the present invention.

[0064] It should be noted that, in this article, relational terms such as first and second, etc. are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Moreover, the terms "include", "comprise" or any other variants are intended to cover non-exclusive inclusion, so that an article or device including a series of elements includes not only those elements, but also other elements that are not explicitly listed. In the absence of more restrictions, the elements defined by the statement "including one..." do not exclude the existence of other identical elements in the article or device including the elements.

[0065] In order to quickly calculate large models containing multi-layer metal meshes, the embodiment of the present invention proposes an efficient method for obtaining low-frequency transmission characteristics of multi-layer metal meshes based on FDTD. This method can quickly calculate the transmission characteristics of large engineering models containing metal meshes, greatly improve the calculation efficiency while ensuring the calculation accuracy, and reduce the consumption of computing resources. Please refer to Figure 1 , Figure 1 The flowchart of a method for efficiently acquiring low-frequency transmission characteristics of a multi-layer metal mesh model based on FDTD provided by an embodiment of the present invention includes:

[0066] S1: Obtain the shielding effectiveness of multi-layer metal mesh.

[0067] The multi-layer metal mesh comprises n layers of metal mesh with the same material and thickness, which are the 1st, 3rd, ..., 2n-1th layers respectively, and air layers are sandwiched between two metal layers, which are the 2nd, 4th, ..., 2n-2th layers respectively.

[0068] The shielding effectiveness analytical model for multiple layers of metal mesh with the same structure and material is:

[0069] SE n层,网 =(R 1 +R 3 +…+R 2n-1 )+(M 2 +M 4 +…+M 2n-2 ) (1)

[0070] Among them, SE n层,网 It represents the shielding effectiveness of n-layer metal mesh, n represents the number of layers of metal mesh, R 2n-1 represents the reflection loss of the 2n-1th layer of metal mesh, M 2n-2 Represents the multiple reflection loss of the 2n-2th air interlayer.

[0071] S2: Obtain the polarizability function of the multilayer metal mesh equivalent dispersion model.

[0072] By analyzing the calculation results of step S1, an equivalent dispersion model suitable for the transmission characteristics of the multilayer metal mesh is given. The dielectric constant ε of the commonly used frequency domain models of dispersive media, such as the Drude model, Debye model, and Lorentz model r The characteristic diagram that changes with frequency ω is as follows: Figure 2 As shown. Figure 2 In the figure, O is the origin of the coordinate system, and the real and imaginary parts of the dielectric constant are represented by ε' r and ε” r express.

[0073] Depend on Figure 2 It can be seen that the dielectric coefficients of common dispersion models are all quadratic functions, and these dispersion models cannot fit the equivalent dielectric parameters of the metal mesh well in the low frequency band. Since the transmission coefficient of the metal mesh is a quasi-linear curve in the low frequency band, and for an infinite metal mesh, the transmission coefficient is zero when the frequency is zero when the dielectric loss is ignored. Therefore, the polarizability function of the multilayer metal mesh equivalent dispersion model constructed in the embodiment of the present invention is:

[0074] χ(ω)=Kω (2)

[0075] Among them, ω is the electromagnetic frequency, and K is the polarizability parameter (which can be determined by the metal mesh structure parameters). Subsequent calculations show that this model can fit the transmission characteristics of the metal mesh well.

[0076] S3: Obtain the circular convolution-finite difference time-domain formula for calculating the transmission characteristics of the multi-layer metal mesh.

[0077] According to the metal mesh polarizability function of the equivalent dispersion model proposed in step S2, the frequency domain constitutive relation of the equivalent dispersion model can be obtained. In the time domain calculation, it is necessary to convert the frequency domain constitutive relation of the dispersion medium to the time domain for processing, and finally obtain the time domain iterative calculation formula of the electric field and the magnetic field. The methods for processing the dispersion medium problem in FDTD (finite difference time domain method) include RC (circular convolution) method, Z transform method and shift operator method, etc. The embodiment of the present invention adopts the RC method.

[0078] Specifically, step S3 of this embodiment includes:

[0079] Obtain a discretized form of the Maxwell curl for a linear isotropic medium in the lossless case:

[0080]

[0081] Where E, H, and D represent the electric field intensity, magnetic field intensity, and electric flux density, respectively; Δt is the time interval; and μ represents the magnetic permeability coefficient. represents the Hamiltonian operator.

[0082] The first formula in formula (3) can be used to obtain the electric flux density D through the magnetic field intensity H, and the second formula can be used to obtain the magnetic field intensity H from the electric field intensity E. Its frequency domain constitutive relationship is:

[0083]

[0084] Where B represents the magnetic flux density, ω is the electromagnetic frequency, and ε(ω) is the dielectric constant, which is a function of the electromagnetic frequency. The second equation in formula (4) can be used to obtain the time domain recursive formula from the electric flux density D to the electric field intensity E. Since the dielectric constant ε(ω) is related to the electromagnetic frequency ω, the specific form of the dielectric constant ε(ω) is related to the dispersion characteristics of the medium.

[0085] The frequency domain constitutive relation of the dispersive medium is:

[0086] D(ω)=ε 0 E(ω)+ε 0 χ(ω)·E(ω) (5)

[0087] Among them, ε 0 is the vacuum dielectric constant, and χ(ω) is the polarizability function of the metal mesh. Formula (5) contains the product of the frequency-varying polarizability function χ(ω) and the frequency-varying electric field function E(ω). According to the Fourier transform theory, the product of the two frequency domain functions becomes the convolution of the two functions in the time domain after the Fourier transform. Therefore, the expression of formula (5) after the Fourier transform is:

[0088]

[0089] Where t represents time, τ represents the integral variable, D(t) represents the electric flux density in the time domain, and E(t) represents the electric field intensity in the time domain. After discretization, the step formula of D→E of the dispersive medium in the discrete time domain is:

[0090]

[0091] Among them, ε ∞ is the relative dielectric constant when the frequency is infinite, Δχ m represents the rate of change of the polarizability function of the metal mesh, χ 0 is the 0th polarizability function, and the mth polarizability function is:

[0092]

[0093] Wherein, Δt represents the time interval.

[0094] Formula (7) requires all past time values ​​of E, which makes the calculation inconvenient. In order to simplify the summation calculation, an auxiliary variable is introduced Then the step formula of D→E in the RC-FDTD method is converted into the circular convolution-finite difference time domain formula:

[0095]

[0096] The χ corresponding to the multilayer metal mesh dispersion model is given below m , χ 0 , Δχ m and the auxiliary variable ψ n The specific expression of .

[0097] The Fourier transform of the polarizability function χ(ω) = Kω is used We can get:

[0098]

[0099] Then 0 =KΔt 3 / 3π、Δχ m = x m -x m+1 =-2K(m+1)Δt 3 / π.

[0100] Introducing auxiliary variables Then the auxiliary variable ψ n It can be expressed as:

[0101]

[0102] S4: Genetic algorithm and shielding effectiveness are used to invert the electromagnetic parameters of the single-layer equivalent medium to obtain the polarizability parameter K for constructing the polarizability function.

[0103] Specifically, step S4 of this embodiment includes:

[0104] S4.1: Generate a random number as parameter K through a binary string;

[0105] S4.2: Calculate the shielding effectiveness of the single-layer equivalent medium using the parameter K and the circular convolution-finite difference time-domain formula, and calculate the error with the shielding effectiveness obtained in step S1;

[0106] S4.3: Repeat steps S4.1 and S4.2, and determine whether the error is less than 10 -4 If the conditions are met, the process ends and the final polarizability parameter K is obtained.

[0107] S5: The transmission characteristics of the model containing multi-layer metal mesh are obtained using the circular convolution-finite difference time-domain formula and the polarizability parameter K.

[0108] Specifically, the transmission characteristics of the model containing the multi-layer metal mesh are calculated according to the circular convolution-finite difference time domain formula obtained in step S3 and the final electromagnetic parameter K obtained in step S4.

[0109] In order to verify the accuracy and efficiency of the method for efficiently acquiring the low-frequency transmission characteristics of the multi-layer metal mesh proposed in the present invention, the shielding effectiveness of the two-dimensional infinite metal mesh and the dielectric cavity with the metal mesh are calculated respectively below.

[0110] (1) Shielding effectiveness of two-dimensional infinite metal mesh

[0111] The thickness of the equivalent medium, the size of the grid and the polarizability parameter K will affect the shielding effectiveness of the metal mesh. When inverting the specific parameters of the equivalent dispersive medium, the thickness and grid size of the equivalent dispersive medium are assumed to be known quantities, and the polarizability parameter K of the single-layer equivalent medium is inverted based on the shielding effectiveness of the multi-layer metal mesh. The diameter of the metal mesh is 12mm, the mesh size is 300mm, and the spacing between the metal mesh layers is 300mm. The incident pulse is a Gaussian pulse, such as Figure 3 shown.

[0112] The shielding effectiveness analytical model of multi-layer metal mesh is used to calculate the shielding effectiveness of metal meshes with different numbers of layers under vertical incidence. Then, based on the analytical results of the multi-layer metal mesh, the polarizability parameter K of metal meshes with different numbers of layers is inverted using the RC-FDTD method and genetic algorithm. The specific parameters are shown in Table 1.

[0113] Table 1 Equivalent medium parameters

[0114] Metal mesh layers Equivalent dielectric thickness Mesh size Polarizability parameter K Single layer 50mm 50mm <![CDATA[9.96×10 28 ]]> Double Layer 312mm 50mm <![CDATA[6.54×10 28 ]]> Three-layer 612mm 50mm <![CDATA[5.646×10 28 ]]> Four layers 912mm 50mm <![CDATA[5.245×10 28 ]]>

[0115] In order to verify the accuracy of the equivalent dispersion model of the multi-layer metal mesh proposed in the embodiment of the present invention, the transmission waveform and shielding effectiveness of metal meshes with different numbers of layers are calculated using commercial software CST and equivalent methods, as shown in Figure 2. Figure 4 , Figure 5 , Figure 6 As shown, Figure 4 It is a schematic diagram of the transmission waveform and shielding effectiveness of a single-layer metal mesh obtained by different methods; Figure 5 It is a schematic diagram of the transmission waveform and shielding effectiveness of the double-layer metal mesh obtained by different methods; Figure 6 is a schematic diagram of the three-dimensional shielding effectiveness of three-layer metal mesh and four-layer metal mesh obtained by different methods, where CST represents the commercial software CST, which is Figure 4 , Figure 5 and Figure 6 It can be seen that the transmission waveform and shielding effectiveness of the equivalent dispersive medium of the present invention are basically consistent with the calculations of the commercial software CST, and this result proves the accuracy of the method of the present invention.

[0116] (2) Dielectric cavity with metal mesh

[0117] The results of the two-dimensional infinite metal mesh calculated above are applied to the electromagnetic calculation of the three-dimensional model. In order to verify the high efficiency of the method of the present invention, the shielding effectiveness of the dielectric cavity with a metal mesh at the mouth is calculated. The cavity wall thickness is 200mm, and the specific parameters of the medium are: relative dielectric constant ε r =1.0, conductivity σ = 0.01S / m, relative magnetic permeability μ r =1.0. The metal mesh at the mouth of the medium cavity is equivalent to a uniform dispersion medium, such as Figure 7 The specific parameters of the equivalent medium are shown in Table 2. The shielding effectiveness of the dielectric cavity is calculated using the commercial software CST, the traditional FDTD method and the method of the present invention, as shown in Table 2. Figure 8 and Fig. 9 shown.

[0118] Figure 8 and Fig. 9 The shielding effectiveness of the three-dimensional model of different layers of metal mesh calculated using the commercial software CST, the traditional FDTD method and the method of the present invention is shown. It can be seen that the calculation results of the three methods are basically consistent, which proves the accuracy and practicality of the method of the present invention.

[0119] Table 2 Model size and number of grids for different methods

[0120]

[0121] Table 3 CPU time and memory of different methods

[0122]

[0123] Tables 2 and 3 show the geometric dimensions, number of computational grids, memory usage, and time ratio of the traditional FDTD and the method of the present invention. Taking a double-layer metal mesh as an example, the total time of the method of the present invention is only 0.25% of that of the traditional FDTD; the memory usage is only 3.83% of that of the traditional method. This is because the use of a single-layer uniform medium instead of a metal mesh avoids the multi-scale problem, and a larger grid can be used to calculate the model. In addition, the greater the difference between the metal diameter and the model size, the more obvious the acceleration effect.

[0124] The FDTD-based efficient acquisition method for low-frequency transmission characteristics of a multi-layer metal mesh model proposed in the present invention can use a larger metal mesh to calculate a large-scale model containing a metal mesh, greatly improving the calculation efficiency and reducing resource consumption while ensuring the calculation accuracy. The present invention proposes a dispersion model for the shielding effectiveness of a multi-layer metal mesh, and the dispersion model can well describe the law of the transmission efficiency of the multi-layer metal mesh. The present invention provides a new idea for calculating the transmission efficiency of a large model containing a multi-layer metal mesh.

[0125] Another embodiment of the present invention provides a storage medium, wherein a computer program is stored in the storage medium, and the computer program is used to execute the steps of the method for efficiently acquiring the low-frequency transmission characteristics of a multi-layer metal mesh model based on FDTD as described in the above embodiment. Another aspect of the present invention provides an electronic device, including a memory and a processor, wherein a computer program is stored in the memory, and when the processor calls the computer program in the memory, the steps of the method for efficiently acquiring the low-frequency transmission characteristics of a multi-layer metal mesh model based on FDTD as described in the above embodiment are implemented. Specifically, the above integrated module implemented in the form of a software function module can be stored in a computer-readable storage medium. The above software function module is stored in a storage medium, including several instructions for enabling an electronic device (which can be a personal computer, a server, or a network device, etc.) or a processor (processor) to execute some steps of the method described in each embodiment of the present invention. The aforementioned storage medium includes: various media that can store program codes, such as a U disk, a mobile hard disk, a read-only memory (ROM), a random access memory (RAM), a disk or an optical disk.

[0126] The above contents are further detailed descriptions of the present invention in combination with specific preferred embodiments, and it cannot be determined that the specific implementation of the present invention is limited to these descriptions. For ordinary technicians in the technical field to which the present invention belongs, several simple deductions or substitutions can be made without departing from the concept of the present invention, which should be regarded as falling within the scope of protection of the present invention.

Claims

1. A method for efficiently acquiring low-frequency transmission characteristics of a multi-layer metal mesh model based on FDTD, characterized in that: include: S1: Obtain the shielding effectiveness of multi-layer metal mesh; S2: Obtain the polarizability function of the multilayer metal mesh equivalent dispersion model; S3: Obtain the circular convolution-finite difference time-domain formula for calculating the transmission characteristics of the multi-layer metal mesh; S4: using a genetic algorithm and the shielding effectiveness to invert the electromagnetic parameters of a single-layer equivalent medium, and obtaining a polarizability parameter K for constructing a polarizability function; S5: using the circular convolution-finite difference time domain formula and the polarizability parameter K to obtain the transmission characteristics of the model containing the multi-layer metal mesh, The S3 includes: S3.1: Obtain the discretized form of the Maxwell curl of a linear isotropic medium in the lossless case: Where E, H, and D represent the electric field intensity, magnetic field intensity, and electric flux density, respectively; Δt is the time interval; and μ represents the magnetic permeability coefficient. represents the Hamiltonian operator, n represents the nth layer of metal mesh; S3.2: Obtain the frequency domain constitutive relation of the dispersive medium of the equivalent dispersion model: D(ω)=ε0E(ω)+ε0χ(ω)·E(ω), Among them, ε0 is the vacuum dielectric constant, χ(ω) is the polarizability function of the metal mesh, and ω is the electromagnetic frequency; S3.3: Perform Fourier transform on the frequency domain constitutive relation to obtain the Fourier transformed expression: Where t represents time, τ represents the integral variable, D(t) represents the electric flux density in the time domain, and E(t) represents the electric field intensity in the time domain; S3.4: After obtaining the discretization, the step formula of D→E of the dispersive medium in the discrete time domain is: Among them, ε ∞ is the relative dielectric constant when the frequency is infinite, Δχ m represents the rate of change of the polarizability function of the metal mesh, χ0 is the 0th term of the polarizability function; S3.5: Introducing auxiliary variables The step formula of D→E is converted to form the circular convolution-finite difference time domain formula: After S3.5, the following is also included: Obtain χ0 and Δχ corresponding to the equivalent dispersion model of the multilayer metal mesh m and auxiliary variable ψ n The specific expression of .

2. The method for efficiently acquiring low-frequency transmission characteristics of a multi-layer metal mesh model based on FDTD according to claim 1 is characterized in that: The multi-layer metal mesh comprises n layers of metal mesh with the same material and thickness, and an air interlayer is formed between two metal layers, wherein the first, third, ..., 2n-1 layers are metal meshes, and the second, fourth, ..., 2n-2 layers are air interlayers; The analytical model of the shielding effectiveness of the multi-layer metal mesh is: SE n层,网 =(R1+R3+…+R 2n-1 )+(M2+M4+…+M 2n-2 ), Among them, SE n层,网 It represents the shielding effectiveness of n-layer metal mesh, n represents the number of layers of metal mesh, R 2n-1 represents the reflection loss of the 2n-1th layer of metal mesh, M 2n-2 Represents the multiple reflection loss of the 2n-2th air interlayer.

3. The method for efficiently acquiring low-frequency transmission characteristics of a multi-layer metal mesh model based on FDTD according to claim 1 is characterized in that: The metal mesh polarizability function expression of the equivalent dispersion model is: χ(ω)=Kω, Among them, ω is the electromagnetic frequency and K is the polarizability parameter.

4. The method for efficiently acquiring low-frequency transmission characteristics of a multi-layer metal mesh model based on FDTD according to claim 3 is characterized in that: Obtain χ0 and Δχ corresponding to the equivalent dispersion model of the multilayer metal mesh m and auxiliary variable ψ n The specific expressions include: Performing Fourier transform on the polarizability function χ(ω)=Kω, we obtain: Then χ0 = KΔt 3 / 3π, Δχ m = χ m - χ m+1 = -2K(m + 1)Δt 3 / π; Introducing auxiliary variables Then the auxiliary variable ψ n It is expressed as:

5. The method for efficiently acquiring low-frequency transmission characteristics of a multi-layer metal mesh model based on FDTD according to claim 3 is characterized in that: The S4 includes: S4.1: Generate a random number as parameter K through a binary string; S4.2: Calculate the shielding effectiveness of a single-layer equivalent medium using the parameter K and the circular convolution-finite difference time-domain formula, and calculate the error with the shielding effectiveness obtained in step S1; S4.3: Repeat steps S4.1 and S4.2, and determine whether the error is less than 10 -4 , if the conditions are met, the process ends and the final K value is obtained.

6. A storage medium storing a computer program for executing the steps of the method for efficiently acquiring low-frequency transmission characteristics of a multi-layer metal mesh model based on FDTD as recited in claims 1 to 5.

7. An electronic device comprising a memory and a processor, wherein the memory stores a computer program, and when the processor calls the computer program in the memory, the processor implements the steps of the method for efficiently acquiring low-frequency transmission characteristics of a multi-layer metal mesh model based on FDTD as described in any one of claims 1 to 5.

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