CN111103327B - Equivalent electromagnetic parameter inversion method and device for artificial structure with non-uniform dielectric material - Google Patents
Equivalent electromagnetic parameter inversion method and device for artificial structure with non-uniform dielectric material Download PDFInfo
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Abstract
The invention provides an equivalent electromagnetic parameter inversion method and device for an artificial structure with nonuniform dielectric material, wherein the method comprises the following steps: cutting the artificial structure layer by layer; the initial positioning of the electromagnetic parameters of each layer of artificial structure is realized; calculating and fitting the distribution trend of equivalent electromagnetic parameters of the layered artificial structure by combining a numerical analysis method and a material structure parameter theory; calculating a material equivalent electromagnetic parameter search optimization space based on the structural equivalent parameter theory and the distribution trend of the layered artificial structure equivalent electromagnetic parameters; generating a material equivalent electromagnetic parameter gene by using a genetic algorithm; and processing the equivalent electromagnetic parameter gene of the material by using a genetic algorithm. According to the scheme of the invention, electromagnetic parameter inversion with small error and easy realization is realized for the artificial structure with non-uniform dielectric material.
Description
Technical Field
The invention relates to the field of artificial structures of dielectric materials, in particular to an equivalent electromagnetic parameter inversion method and device of an artificial structure with nonuniform dielectric materials.
Background
With the continuous improvement of modern electronic information transmission, antenna, radar, network, stealth and other technologies, the requirements on the electromagnetic performance of new materials are higher and higher, and the artificial structure of the dielectric material with special electromagnetic performance requirements is widely researched. The equivalent electromagnetic parameter inversion of the artificial structure of the dielectric material is the most direct and effective means for analyzing, understanding and recognizing the electromagnetic performance of the artificial structure of the dielectric material, and is also an effective basis for customizing the performance of a novel metamaterial, designing the structure and engineering.
At present, the commonly used method for inverting electromagnetic parameters of the artificial structure of the dielectric material mainly comprises theoretical formula inversion, Smith S electromagnetic parameter inversion and the like. The theoretical formula inversion calculates equivalent electromagnetic parameters of the artificial structure of the medium material based on different models, and has certain requirements on the structure periodicity of the medium material, namely, a calculation object has greater limitation. The Smith S electromagnetic parameter inversion eliminates the dependence on the periodicity of the medium structure, the inversion effect on the complex structure is superior to that of a theoretical calculation method, but certain errors exist in the inversion effect on the three-dimensional structure. For a three-dimensional medium material artificial structure, the precision is improved by adopting layered inversion combination, but because each single-layer inversion has a certain amount of errors, the errors of the multi-layer medium inversion are accumulated, and the deviation of the integral inversion effect is increased.
For the artificial structure with non-uniform medium material, the prior art is further lack of an electromagnetic parameter inversion method with small error and easy realization.
Disclosure of Invention
In order to solve the technical problems, the invention provides an equivalent electromagnetic parameter inversion method and device for an artificial structure with non-uniform dielectric material, and the method and device are used for solving the technical problems that the artificial structure with non-uniform dielectric material lacks small errors and is easy to implement in the prior art.
According to a first aspect of the invention, an artificial structure equivalent electromagnetic parameter inversion method for non-uniform dielectric materials is provided, which comprises the following steps:
step S101: cutting the artificial structure layer by layer according to the thickness of the artificial structure from the input direction to the output direction, and marking layer numbers, wherein the thickness of each cut layer is equal;
step S102: inverting the material equivalent electromagnetic parameters of each layer of artificial structure by using a layered inversion algorithm, namely inverting the material equivalent electromagnetic parameters of each layer of artificial structure by using a layered structure equivalent parameter theory or a Smith S electromagnetic parameter inversion method, and realizing the initial positioning of the electromagnetic parameters of each layer of artificial structure; the equivalent electromagnetic parameters of the material are equivalent to the electromagnetic parameters;
step S103: obtaining the initially positioned electromagnetic parameters of each layer, and calculating and correlating the obtained initially positioned electromagnetic parameters of each layer by combining a numerical analysis method and theoretical calculation of material structure parameters to obtain the distribution trend of the fitted artificial structure equivalent electromagnetic parameters, wherein the distribution trend is curve data;
step S104: initializing the current layer as the 1 st layer;
step S105: acquiring a current layer, judging whether the current layer is larger than the layering number of the artificial structure, and if so, entering step S1010; if not, the step S106 is carried out;
step S106: calculating the material equivalent electromagnetic parameter search optimization space of the current layer based on the structural equivalent parameter theory and the distribution trend of the artificial structure equivalent electromagnetic parameters;
step S107: generating a material equivalent electromagnetic parameter gene of a current layer by utilizing a genetic algorithm, wherein the material equivalent electromagnetic parameter gene of the current layer is provided with a plurality of gene strings, and the number of the gene strings is the same as that of the material equivalent electromagnetic parameter of the current layer;
step S108: processing the material equivalent electromagnetic parameter gene by using a genetic algorithm to generate a new material equivalent electromagnetic parameter gene, simulating the generated new material equivalent electromagnetic parameter gene to generate curve data, calculating the score value of the performance of the non-uniform artificial structure equivalent electromagnetic parameter of the medium material, and determining the curve similarity distance based on the score value;
step S109: judging whether the curve similarity distance error is smaller than a set value, if so, recording the equivalent electromagnetic parameter gene of the optimal material of the current layer, adding 1 to the layer number of the current layer, namely, preparing to process the next layer of the layered structure, and entering step S105, otherwise, entering step S108;
step S1010: outputting the optimal equivalent electromagnetic parameter genes of each layer, inputting the optimal equivalent electromagnetic parameter genes of each layer into an FDTD model, and simulating to obtain the equivalent electromagnetic parameters of the artificial structure with the nonuniform medium material.
Further, the artificial structure with the nonuniform medium material comprises a composite material layer and a medium material functional layer which are arranged in the direction from input to output, corresponding parameters are set for the composite material layer according to different application material attributes, and the artificial medium material functional layer realizes inversion of electromagnetic parameters and performance through S parameter hierarchical inversion, parameter distribution trend fitting, search space calculation and genetic algorithm iteration.
Further, the equivalent electromagnetic parameter inversion of the artificial structure with the non-uniform medium material firstly carries out the initial positioning of the equivalent electromagnetic parameters through the theoretical algorithm Motamedi or Smith S parameter inversion.
Further, the breadth of the search space is numerically approximated based on the dimension and duty ratio of the artificial structure and the limit condition of the material of the artificial structure.
Further, when the medium material functional layer of the artificial structure is layered, the thickness of the layering can be set according to requirements.
Further, the step S108: processing the material equivalent electromagnetic parameter gene by using a genetic algorithm to generate a new material equivalent electromagnetic parameter gene, simulating the generated new material equivalent electromagnetic parameter gene to generate curve data, calculating the performance score value of the non-uniform artificial structure equivalent electromagnetic parameter of the medium material, and determining a curve similarity distance based on the score value, wherein the process comprises the following steps:
step S1081: generating gene crossing and mutation rules based on the influence characteristics of the dielectric constant and the loss tangent on the overall wave transmission performance; and carrying out crossover and mutation operations on the genes to generate new genes;
step S1082: carrying out simulation by using an FDTD simulation structure to obtain parameter simulation S21 curve data of the new gene;
step S1083: calculating the performance score value of the non-uniform artificial structure equivalent electromagnetic parameters of the medium material, and determining the curve similarity distance based on the performance score value of the equivalent electromagnetic parameters, namely calculating
Where dis (S)1,S2) Represents twoComprehensive quantification of the degree of similarity of the bar curves, first term in the formula
Is the Euclidean distance of two vectors, the second term | | | S1|·|S2|-<S1,S2>The absolute value of the difference between the inner product of the two vectors and the product of the two vector modes is |, and the larger the value is, the worse the vector form similarity is; the first item represents the space distance of the two vectors and is used for searching the parameter with the closest space distance in the parameter optimization process; the second term embodies the morphological similarity of the two vectors.
Further, the gene length is 20 bits, the population size is 100, and the distribution probability density is gaussian distribution.
According to a second aspect of the present invention, there is provided an apparatus for inverting equivalent electromagnetic parameters of an artificial structure with inhomogeneous dielectric material, the apparatus comprising:
cutting the module: cutting the artificial structure layer by layer according to the thickness of the artificial structure from the input direction to the output direction, and marking layer numbers, wherein the thickness of each cut layer is equal;
the primary positioning module: inverting the material equivalent electromagnetic parameters of each layer of artificial structure by using a layered inversion algorithm, namely inverting the material equivalent electromagnetic parameters of each layer of artificial structure by using a layered structure equivalent parameter theory or a Smith S electromagnetic parameter inversion method, and realizing the initial positioning of the electromagnetic parameters of each layer of artificial structure; the equivalent electromagnetic parameters of the material are equivalent to the electromagnetic parameters;
a distribution trend generation module: obtaining the initially positioned electromagnetic parameters of each layer, and calculating and correlating the obtained initially positioned electromagnetic parameters of each layer by combining a numerical analysis method and theoretical calculation of material structure parameters to obtain the distribution trend of the fitted artificial structure equivalent electromagnetic parameters, wherein the distribution trend is curve data;
an initialization module: initializing the current layer as the 1 st layer;
a first judging module: the system is used for acquiring a current layer and judging whether the current layer is larger than the layering number of the artificial structure;
determining an optimization space module: calculating the material equivalent electromagnetic parameter search optimization space of the current layer based on the structural equivalent parameter theory and the distribution trend of the artificial structure equivalent electromagnetic parameters;
a gene generation module: generating a material equivalent electromagnetic parameter gene of a current layer by utilizing a genetic algorithm, wherein the material equivalent electromagnetic parameter gene of the current layer is provided with a plurality of gene strings, and the number of the gene strings is the same as that of the material equivalent electromagnetic parameter of the current layer;
a genetic algorithm optimizing module: processing the material equivalent electromagnetic parameter gene by using a genetic algorithm to generate a new material equivalent electromagnetic parameter gene, simulating the generated new material equivalent electromagnetic parameter gene to generate curve data, calculating the score value of the performance of the non-uniform artificial structure equivalent electromagnetic parameter of the medium material, and determining the curve similarity distance based on the score value;
a second judging module: judging whether the curve similarity distance error is smaller than a set value or not;
an output module: outputting the optimal equivalent electromagnetic parameter genes of each layer, inputting the optimal equivalent electromagnetic parameter genes of each layer into an FDTD model, and simulating to obtain the equivalent electromagnetic parameters of the artificial structure with the nonuniform medium material.
According to a third aspect of the present invention, there is provided an artificial structure equivalent electromagnetic parameter inversion system for non-uniform dielectric material, comprising:
a processor for executing a plurality of instructions;
a memory to store a plurality of instructions;
wherein the instructions are configured to be stored in the memory and loaded by the processor to perform the artificial structure equivalent electromagnetic parameter inversion method for the inhomogeneous dielectric material.
According to a fourth aspect of the present invention, there is provided a computer readable storage medium having a plurality of instructions stored therein; the instructions are used for loading and executing the artificial structure equivalent electromagnetic parameter inversion method of the non-uniform medium material by a processor.
According to the scheme, initial electromagnetic parameters of the artificial structure of the layered medium material are preliminarily determined by introducing a Smith S parameter inversion method and a layered inversion method, an optimized parameter search space is determined by calculating the limit condition of an equivalent structure through numerical analysis, and gene optimization is performed by combining an improved genetic algorithm and a gradient descent method. The electromagnetic performance of the inversion parameter model and the electromagnetic performance of the medium material artificial structure are compared in an FDTD environment, and the result shows that the S21 parameter curve can be highly reproduced by the method. The inversion optimization electromagnetic parameters more accurately reflect the electromagnetic performance of the medium material artificial synthesis structure, and can effectively promote the understanding and cognition of researchers on the medium material artificial structure.
The foregoing description is only an overview of the technical solutions of the present invention, and in order to make the technical solutions of the present invention more clearly understood and to implement them in accordance with the contents of the description, the following detailed description is given with reference to the preferred embodiments of the present invention and the accompanying drawings.
Drawings
The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments of the invention and, together with the description, serve to explain the principles of the invention. In the drawings:
FIG. 1 is a flow chart of an equivalent electromagnetic parameter inversion method for an artificial structure with nonuniform dielectric materials according to an embodiment of the present invention;
FIG. 2 is a graph of the periodic pattern dimensions corresponding to 3 layers of a non-uniform artificial structure of dielectric material in accordance with one embodiment of the present invention;
FIG. 3 is a full flow chart of the present invention for implementing electromagnetic parametric inversion;
FIG. 4 is a comparison graph of S21 curves of a parameter optimization method, a Meta-Medi theoretical inversion method and a Smith S parameter inversion method according to an embodiment of the invention;
fig. 5 is a comparison graph of the difference distance value curve of the S21 curve and the S21 curve of the example gradient structure material in the parameter optimization method, the meta-Medi theoretical inversion method and the Smith S parameter inversion method according to the embodiment of the invention;
FIG. 6 is a schematic diagram showing comparison between electromagnetic parameters obtained by parameter optimization and parameters obtained by Meta-Medi theoretical inversion and Smith S parameter inversion according to an embodiment of the present invention
Fig. 7 is a structural block diagram of an artificial structure equivalent electromagnetic parameter inversion apparatus for non-uniform dielectric materials according to an embodiment of the present invention.
Detailed Description
In order to make the objects, technical solutions and advantages of the present invention more apparent, the technical solutions of the present invention will be clearly and completely described below with reference to the specific embodiments of the present invention and the accompanying drawings. It is to be understood that the described embodiments are merely exemplary of the invention, and not restrictive of the full scope of the invention. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
First, a flow chart of an equivalent electromagnetic parameter inversion method of an artificial structure with inhomogeneous dielectric material according to an embodiment of the present invention is described with reference to fig. 1. As shown in fig. 1, the artificial structure with heterogeneous medium material comprises a composite material and an artificial medium material, and the method comprises the following steps:
step S101: cutting the artificial structure layer by layer according to the thickness of the artificial structure from the input direction to the output direction, and marking layer numbers, wherein the thickness of each cut layer is equal;
step S102: inverting the material equivalent electromagnetic parameters of each layer of artificial structure by using a layered inversion algorithm, namely inverting the material equivalent electromagnetic parameters of each layer of artificial structure by using a layered structure equivalent parameter theory or a Smith S electromagnetic parameter inversion method, and realizing the initial positioning of the electromagnetic parameters of each layer of artificial structure; the equivalent electromagnetic parameters of the material are equivalent to the electromagnetic parameters;
step S103: obtaining the initially positioned electromagnetic parameters of each layer, and calculating and correlating the obtained initially positioned electromagnetic parameters of each layer by combining a numerical analysis method and theoretical calculation of material structure parameters to obtain the distribution trend of the fitted artificial structure equivalent electromagnetic parameters, wherein the distribution trend is curve data;
step S104: initializing the current layer as the 1 st layer;
step S105: acquiring a current layer, judging whether the current layer is larger than the layering number of the artificial structure, and if so, entering step S1010; if not, the step S106 is carried out;
step S106: calculating the material equivalent electromagnetic parameter search optimization space of the current layer based on the structural equivalent parameter theory and the distribution trend of the artificial structure equivalent electromagnetic parameters;
step S107: generating a material equivalent electromagnetic parameter gene of a current layer by utilizing a genetic algorithm, wherein the material equivalent electromagnetic parameter gene of the current layer is provided with a plurality of gene strings, and the number of the gene strings is the same as that of the material equivalent electromagnetic parameter of the current layer;
step S108: processing the material equivalent electromagnetic parameter gene by using a genetic algorithm to generate a new material equivalent electromagnetic parameter gene, simulating the generated new material equivalent electromagnetic parameter gene to generate curve data, calculating the score value of the performance of the non-uniform artificial structure equivalent electromagnetic parameter of the medium material, and determining the curve similarity distance based on the score value;
step S109: judging whether the curve similarity distance error is smaller than a set value, if so, recording the equivalent electromagnetic parameter gene of the optimal material of the current layer, adding 1 to the layer number of the current layer, namely, preparing to process the next layer of the layered structure, and entering step S105, otherwise, entering step S108;
step S1010: outputting the optimal equivalent electromagnetic parameter genes of each layer, inputting the optimal equivalent electromagnetic parameter genes of each layer into an FDTD model, and simulating to obtain the equivalent electromagnetic parameters of the artificial structure with the nonuniform medium material.
The step S101: according to the thickness of the artificial structure, the artificial structure is cut in layers from the input direction to the output direction and marked with layer numbers, and the thickness of each cut layer is equal, and the method comprises the following steps:
the artificial structure with the nonuniform medium material comprises a composite material layer and a medium material functional layer which are arranged in the direction from input to output, corresponding parameters are set for the composite material layer according to different application material attributes, and the high-precision inversion of electromagnetic parameters and performance is realized by the artificial medium material functional layer through S parameter hierarchical inversion, parameter distribution trend fitting, search space calculation and genetic algorithm iteration.
When the medium material functional layer of the artificial structure is layered, the layered thickness can be set according to requirements, the more the number of layers is, the more the number of iteration times of inversion optimization is, and correspondingly, the higher the inversion precision is.
The step S102: inverting the material equivalent electromagnetic parameters of each layer of artificial structure by using a layered inversion algorithm, namely inverting the material equivalent electromagnetic parameters of each layer of artificial structure by using a layered structure equivalent parameter theory or a Smith S electromagnetic parameter inversion method, and realizing the initial positioning of the electromagnetic parameters of each layer of artificial structure; the material equivalent electromagnetic parameters are equivalent to electromagnetic parameters, and the material equivalent electromagnetic parameters comprise:
the layered inversion algorithm is an inversion performed on the basis that the artificial structure of the dielectric material with non-uniformity in step S101 is uniformly divided into N layers in the height direction, and then each layer is approximately regarded as a uniform structure. In this embodiment, the gradient structure shown in fig. 2 is cut into layers to obtain a multilayered layered structure with uniform thickness, and a cuboid with a square cross section is subjected to multilayer approximation. The equivalent electromagnetic parameters of the inverted material of each layer of artificial structure are directly calculated by using the equivalent parameter theory of the layered structure or the Smith S electromagnetic parameter inversion method, namely, the equivalent electromagnetic parameters of the material are obtained by using the volume ratio of the single cell/each layer of the artificial structure with non-uniform medium material by adopting an empirical formula algorithm (such as a Motamedi formula) or the Smith S electromagnetic parameter inversion method. Therefore, an initial value of the material variation trend can be obtained, but certain errors exist in the two modes plus the layering equivalence, so that the matching optimization of the equivalent electromagnetic parameters of the material with better and smaller errors is carried out by adopting a subsequent mode based on a genetic algorithm on the basis of the initial value.
Fig. 2 is a schematic diagram of the dimensions of a periodic pattern corresponding to 3 layers of an artificial structure with nonuniform dielectric material according to an embodiment of the present invention, as shown in fig. 2:
the artificial structure is an artificial synthetic gradient periodic structure material, the height of the whole artificial structure is h-6 mm, the upper radius is 5mm, the lower radius is 8mm, the dielectric constant epsilon of the material is 3.75, and the loss tangent is tan D of 0.008. In this embodiment, each gradient unit structure is layered into 3 layers, each layer has a thickness di of 2mm, the radius pair is (5mm,6mm), (6mm,7mm), and (7mm,8mm) in sequence from top to bottom, electromagnetic parameters and loss tangent coarse positioning of each layer are (1.69, 0.007), (2.01, 0.012), (2.46, 0.019) respectively by Smith S parameter inversion, and electromagnetic parameter optimization calculation is further performed on the layered structure by using the precise optimization inversion method provided by the present invention.
The initially positioned parameters reflect the variation trend of the initially positioned parameters, the distribution trend can be generated, and the distribution trend is used as one of the bases for parameter generation in the genetic algorithm, so that the optimization efficiency is improved.
The step S103: obtaining the initially positioned electromagnetic parameters of each layer, and combining a numerical analysis method and theoretical calculation of material structure parameters, calculating and correlating the obtained initially positioned electromagnetic parameters of each layer to obtain a distribution trend of the fitted artificial structure equivalent electromagnetic parameters, wherein the distribution trend is curve data and comprises the following steps:
calculating and correlating the obtained electromagnetic parameters of each layer after initial positioning by combining a numerical analysis method and a material structure parameter theory, and simulating by using a general FDTD simulation model to obtain simulation S21 parameter curve data; the simulation S21 parametric curve represents the distribution trend of the equivalent electromagnetic parameters of the layered artificial structure.
The numerical analysis method and the theoretical calculation of the material structure parameters in this embodiment adopt methods common in the art, and the FDTD simulation method is also a method common in the art. The known curve fitting method is adopted for fitting the distribution parameters of equivalent electromagnetic parameters of the layered artificial structure. The method available in the field is applied to the layered equivalent structure to fit each layered structure.
Step S106: the method comprises the steps of calculating material equivalent electromagnetic parameters of a current layer to search an optimization space based on a structural equivalent parameter theory and a distribution trend of the artificial structure equivalent electromagnetic parameters, wherein in the embodiment, the breadth of the search space is calculated numerically and approximately based on the size and duty ratio of the artificial structure and the limit condition of the artificial structure material. The material equivalent electromagnetic parameters of the current layer can be determined to search the optimization space based on the calculation of use requirements.
The structure equivalent parameter theory of the embodiment is the Mota-Medi theory. That is to say, the material equivalent electromagnetic parameter searching space is determined on the basis of the distribution trend, so that the material equivalent electromagnetic parameters corresponding to each layer can float up and down in a limited small space, and the optimization efficiency is accelerated on the basis of ensuring the change trend.
The step S107: generating a material equivalent electromagnetic parameter gene of a current layer by utilizing a genetic algorithm, wherein the material equivalent electromagnetic parameter gene of the current layer is provided with a plurality of gene strings, and the number of the gene strings is the same as that of the material equivalent electromagnetic parameter of the current layer, and the method comprises the following steps:
generating trend parameter genes for the layered equivalent medium;
in this example, the gene length was 20 bits, the population size was 100, and the distribution probability density was gaussian.
Step S108: processing the material equivalent electromagnetic parameter gene by using a genetic algorithm to generate a new material equivalent electromagnetic parameter gene, simulating the generated new material equivalent electromagnetic parameter gene to generate curve data, calculating the performance score value of the non-uniform artificial structure equivalent electromagnetic parameter of the medium material, and determining a curve similarity distance based on the score value, wherein the process comprises the following steps:
step S1081: generating gene crossing and mutation rules based on the influence characteristics of the dielectric constant and the loss tangent on the overall wave transmission performance; and carrying out crossover and mutation operations on the genes to generate new genes;
step S1082: carrying out simulation by using an FDTD simulation structure to obtain parameter simulation S21 curve data of the new gene;
step S1083: calculating the performance score value of the non-uniform artificial structure equivalent electromagnetic parameters of the medium material, and determining the curve similarity distance based on the performance score value of the equivalent electromagnetic parameters, namely calculating
Where dis (S)1,S2) Representing the degree of similarity of the two curves in a comprehensive quantification, the first term in the formula
Is the Euclidean distance of two vectors, the second term | | | S1|·|S2|-<S1,S2>The absolute value of the difference between the inner product of the two vectors and the product of the two vector modes is |, and the larger the value is, the worse the vector form similarity is; the first item represents the space distance of the two vectors and is used for searching the parameter with the closest space distance in the parameter optimization process; the second term embodies the morphological similarity of the two vectors.
The genetic algorithm of this embodiment is to perform gene crossing, mutation and optimization in the material equivalent electromagnetic parameter search optimization space calculated in step S106.
Fig. 3 is a full flow chart of the present invention for implementing electromagnetic parametric inversion, and as shown in fig. 3, the parametric inversion, model simulation, and genetic algorithm are combined.
Further, in this embodiment, an actual structure numerical value/simulation modeling is directly performed on the whole artificial structure with the non-uniform dielectric material by an FDTD-based method, so as to obtain a first S21 curve; and obtaining equivalent electromagnetic parameters after inversion by a Mota-medi method and a Smith method, namely the two methods, then taking the equivalent electromagnetic parameters obtained by inversion as N-layer material electromagnetic parameters, further performing modeling and numerical analysis by an FDTD method to obtain a second S21 curve, wherein the second S21 curve is an S21 curve of an equivalent structure, and the simulation curve and the inverted material electromagnetic parameters can be corrected by comparing the first S21 curve with the second S21 curve.
The method comprises the steps of adopting an artificial structure shown in figure 2, controlling periodic full-structure parameters by using a genetic algorithm to carry out FDTD simulation modeling, calculating S electromagnetic parameters of the FDTD simulation modeling, comparing the S21 coefficients with the S21 coefficient errors of the whole trapezoidal structure in a reverse mode, preferentially selecting electromagnetic parameter genes, and achieving reduction of the S21 coefficient errors through multiple times of iterative optimization. In the frequency band range of 8-12GHz, the maximum difference of the frequency points of the coefficient of S21 of the gradient structure is less than 0.4%.
On the basis of obtaining layer parameters through inversion, the electromagnetic performance of artificial structures made of different medium materials can be analyzed through simulation design by combining medium layers.
The effect comparison between the embodiment of the invention and other inversion modes is described below with reference to fig. 4-6, fig. 4 is a comparison graph of S21 curves of the parameter optimization method, the meta-Medi theoretical inversion method and the Smith S parameter inversion method according to the embodiment of the invention; fig. 5 is a comparison graph of the difference distance value curve of the S21 curve and the S21 curve of the example gradient structure material in the parameter optimization method, the meta-Medi theoretical inversion method and the Smith S parameter inversion method according to the embodiment of the invention; FIG. 6 is a schematic diagram showing comparison between electromagnetic parameters obtained by parameter optimization and parameters obtained by Meta-Medi theoretical inversion and Smith S parameter inversion according to one embodiment of the invention.
As shown in FIG. 4, the four curves respectively correspond to different electromagnetic parameter inversion methods to obtain S21 coefficient curves through simulation, and the distribution trend of the curves shows that the overall performance parameters of the method are superior to the distribution of the transmission S21 curves of the Mota-Medi theoretical method and the Smith S parameter inversion method, the coefficient difference of S21 at a high-frequency position is large, but the maximum deviation is less than 0.4 percent and far less than 2.8 percent of the Smith S parameter inversion method and superior to 0.52 percent of the Mota-Medi inversion method, and the optimization of multilayer inversion parameters is realized.
As shown in fig. 5, the comparison of the overall performance of the theoretical method, the Smith S-parameter inversion method and the method of the present invention is shown, and the difference between the S21 curve obtained by the theoretical algorithm of Mota-Medi, the Smith S-parameter inversion method and the inversion method of the present invention and the S21 curve of the overall structure is shown in three curves. The S21 curve of the invention shows that the numerical value is basically converged after 10 times of iterative optimization, the difference distance between the curves calculated based on the formula (1) is less than 0.053, and the difference distance can be reduced to 0.049 after 30 times of iteration, which is far less than 0.65 of the Smith S parameter inversion method and is superior to 0.14 of the theoretical method Mota-Medi inversion. The comparison of fig. 5 is numerically quantified to demonstrate the effectiveness and performance superiority of the equivalent parameter optimization of the present invention.
As shown in fig. 6, the method is a meta-Medi theoretical method, a Smith S parameter inversion method and the method of the invention for inversion to obtain electromagnetic parameter comparison, the inversion parameters of the invention follow the dielectric constant distribution characteristics of a gradient structure, and the loss tangent value more conforming to the actual structure in performance is obtained by derivation based on the inversion S21 coefficient.
The embodiment of the present invention further provides an equivalent electromagnetic parameter inversion apparatus for an artificial structure with non-uniform dielectric material, as shown in fig. 7, the apparatus includes:
cutting the module: cutting the artificial structure layer by layer according to the thickness of the artificial structure from the input direction to the output direction, and marking layer numbers, wherein the thickness of each cut layer is equal;
the primary positioning module: inverting the material equivalent electromagnetic parameters of each layer of artificial structure by using a layered inversion algorithm, namely inverting the material equivalent electromagnetic parameters of each layer of artificial structure by using a layered structure equivalent parameter theory or a Smith S electromagnetic parameter inversion method, and realizing the initial positioning of the electromagnetic parameters of each layer of artificial structure; the equivalent electromagnetic parameters of the material are equivalent to the electromagnetic parameters;
a distribution trend generation module: obtaining the initially positioned electromagnetic parameters of each layer, and calculating and correlating the obtained initially positioned electromagnetic parameters of each layer by combining a numerical analysis method and theoretical calculation of material structure parameters to obtain the distribution trend of the fitted artificial structure equivalent electromagnetic parameters, wherein the distribution trend is curve data;
an initialization module: initializing the current layer as the 1 st layer;
a first judgment module: the system is used for acquiring a current layer and judging whether the current layer is larger than the layering number of the artificial structure;
determining an optimization space module: calculating the material equivalent electromagnetic parameter search optimization space of the current layer based on the structural equivalent parameter theory and the distribution trend of the artificial structure equivalent electromagnetic parameters;
a gene generation module: generating a material equivalent electromagnetic parameter gene of a current layer by utilizing a genetic algorithm, wherein the material equivalent electromagnetic parameter gene of the current layer is provided with a plurality of gene strings, and the number of the gene strings is the same as that of the material equivalent electromagnetic parameter of the current layer;
a genetic algorithm optimizing module: processing the material equivalent electromagnetic parameter gene by using a genetic algorithm to generate a new material equivalent electromagnetic parameter gene, simulating the generated new material equivalent electromagnetic parameter gene to generate curve data, calculating the score value of the performance of the non-uniform artificial structure equivalent electromagnetic parameter of the medium material, and determining the curve similarity distance based on the score value;
a second judging module: judging whether the curve similarity distance error is smaller than a set value or not;
an output module: outputting the optimal equivalent electromagnetic parameter genes of each layer, inputting the optimal equivalent electromagnetic parameter genes of each layer into an FDTD model, and simulating to obtain the equivalent electromagnetic parameters of the artificial structure with the nonuniform medium material.
The embodiment of the invention further provides an equivalent electromagnetic parameter inversion system of an artificial structure with non-uniform dielectric materials, which comprises the following steps:
a processor for executing a plurality of instructions;
a memory to store a plurality of instructions;
wherein the instructions are configured to be stored in the memory and loaded by the processor to perform the artificial structure equivalent electromagnetic parameter inversion method for the inhomogeneous dielectric material.
The embodiment of the invention further provides a computer readable storage medium, wherein a plurality of instructions are stored in the storage medium; the instructions are used for loading and executing the artificial structure equivalent electromagnetic parameter inversion method of the non-uniform medium material by a processor.
It should be noted that the embodiments and features of the embodiments may be combined with each other without conflict.
In the several embodiments provided in the present invention, it should be understood that the disclosed system, apparatus and method may be implemented in other ways. For example, the above-described apparatus embodiments are merely illustrative, and for example, the division of the units is only one logical division, and there may be other divisions in actual implementation, for example, a plurality of units or components may be combined or integrated into another system, or some features may be omitted, or not executed. In addition, the shown or discussed mutual coupling or direct coupling or communication connection may be an indirect coupling or communication connection through some interfaces, devices or units, and may be in an electrical, mechanical or other form.
The units described as separate parts may or may not be physically separate, and parts displayed as units may or may not be physical units, may be located in one place, or may be distributed on a plurality of network units. Some or all of the units can be selected according to actual needs to achieve the purpose of the solution of the embodiment.
In addition, functional units in the embodiments of the present invention may be integrated into one processing unit, or each unit may exist alone physically, or two or more units are integrated into one unit. The integrated unit can be realized in a form of hardware, or in a form of hardware plus a software functional unit.
The integrated unit implemented in the form of a software functional unit may be stored in a computer-readable storage medium. The software functional unit is stored in a storage medium and includes several instructions to enable a computer device (which may be a personal computer, a physical machine Server, or a network cloud Server, etc., and needs to install a Windows or Windows Server operating system) to perform some steps of the method according to various embodiments of the present invention. And the aforementioned storage medium includes: various media capable of storing program codes, such as a usb disk, a removable hard disk, a Read-Only Memory (ROM), a Random Access Memory (RAM), a magnetic disk, or an optical disk.
The above description is only a preferred embodiment of the present invention, and is not intended to limit the present invention in any way, and any simple modification, equivalent change and modification made to the above embodiment according to the technical spirit of the present invention are still within the scope of the technical solution of the present invention.
Claims (9)
1. An artificial structure equivalent electromagnetic parameter inversion method for non-uniform dielectric materials is characterized by comprising the following steps:
step S101: cutting the artificial structure layer by layer according to the thickness of the artificial structure from the input direction to the output direction, and marking layer numbers, wherein the thickness of each cut layer is equal;
step S102: inverting the material equivalent electromagnetic parameters of each layer of artificial structure by using a layered inversion algorithm, namely inverting the material equivalent electromagnetic parameters of each layer of artificial structure by using a layered structure equivalent parameter theory or a Smith S electromagnetic parameter inversion method, and realizing the initial positioning of the electromagnetic parameters of each layer of artificial structure; the equivalent electromagnetic parameters of the material are equivalent to the electromagnetic parameters;
step S103: obtaining the initially positioned electromagnetic parameters of each layer, and calculating and correlating the obtained initially positioned electromagnetic parameters of each layer by combining a numerical analysis method and theoretical calculation of equivalent parameters of a material structure to obtain the distribution trend of the fitted equivalent electromagnetic parameters of the artificial structure;
step S104: initializing the current layer as the 1 st layer;
step S105: acquiring a current layer, judging whether the current layer is larger than the layering number of the artificial structure, and if so, entering step S1010; if not, the step S106 is carried out;
step S106: calculating the material equivalent electromagnetic parameter search optimization space of the current layer based on the structural equivalent parameter theory and the distribution trend of the artificial structure equivalent electromagnetic parameters;
step S107: generating a material equivalent electromagnetic parameter gene of a current layer by utilizing a genetic algorithm, wherein the material equivalent electromagnetic parameter gene of the current layer is provided with a plurality of gene strings, and the number of the gene strings is the same as that of the material equivalent electromagnetic parameter of the current layer;
step S108: processing the material equivalent electromagnetic parameter gene by using a genetic algorithm to generate a new material equivalent electromagnetic parameter gene, simulating the generated new material equivalent electromagnetic parameter gene to generate curve data, calculating the score value of the performance of the non-uniform artificial structure equivalent electromagnetic parameter of the medium material, and determining the curve similarity distance based on the score value;
step S109: judging whether the curve similarity distance error is smaller than a set value, if so, recording the equivalent electromagnetic parameter gene of the optimal material of the current layer, adding 1 to the layer number of the current layer, namely, preparing to process the next layer of the layered structure, and entering step S105, otherwise, entering step S108;
step S1010: outputting the optimal material equivalent electromagnetic parameter genes of each layer, inputting the optimal material equivalent electromagnetic parameter genes of each layer into an FDTD model, and simulating to obtain the equivalent electromagnetic parameters of the artificial structure with the nonuniform medium material.
2. The equivalent electromagnetic parameter inversion method of the artificial structure with the nonuniform dielectric material as claimed in claim 1, wherein the artificial structure with the nonuniform dielectric material comprises a composite material layer and a dielectric material functional layer which are arranged from input to output directions, the composite material layer sets corresponding parameters for different application material attributes, and the dielectric material functional layer realizes the inversion of electromagnetic parameters and performance through S parameter hierarchical inversion, parameter distribution trend fitting, search optimization space calculation and genetic algorithm iteration.
3. The method for inverting equivalent electromagnetic parameters of artificial structures with inhomogeneous dielectric materials according to claim 1, wherein the inversion of equivalent electromagnetic parameters of artificial structures with inhomogeneous dielectric materials is performed by performing an initial positioning of equivalent electromagnetic parameters by a theoretical algorithm, Motamedi or Smith S parametric inversion.
4. The method of claim 1, wherein the search for the extent of the optimization space is numerically approximated based on the dimensions and duty cycle of the artificial structure and material limitations of the artificial structure.
5. The method for inverting equivalent electromagnetic parameters of an artificial structure with nonuniform dielectric materials according to claim 2, wherein when the functional layer of the artificial structure dielectric materials is layered, the thickness of the layering is set according to requirements.
6. The method of claim 1, wherein the gene length is 20 bits, the population size is 100, and the distribution probability density is gaussian.
7. An artificial structure equivalent electromagnetic parameter inversion device with inhomogeneous dielectric material, which is characterized by comprising:
cutting the module: cutting the artificial structure layer by layer according to the thickness of the artificial structure from the input direction to the output direction, and marking layer numbers, wherein the thickness of each cut layer is equal;
the primary positioning module: inverting the material equivalent electromagnetic parameters of each layer of artificial structure by using a layered inversion algorithm, namely inverting the material equivalent electromagnetic parameters of each layer of artificial structure by using a layered structure equivalent parameter theory or a Smith S electromagnetic parameter inversion method, and realizing the initial positioning of the electromagnetic parameters of each layer of artificial structure; the equivalent electromagnetic parameters of the material are equivalent to the electromagnetic parameters;
a distribution trend generation module: obtaining the initially positioned electromagnetic parameters of each layer, and calculating and correlating the obtained initially positioned electromagnetic parameters of each layer by combining a numerical analysis method and theoretical calculation of equivalent parameters of a material structure to obtain the distribution trend of the fitted equivalent electromagnetic parameters of the artificial structure;
an initialization module: initializing the current layer as the 1 st layer;
a first judgment module: the system is used for acquiring a current layer and judging whether the current layer is larger than the layering number of the artificial structure;
determining an optimization space module: calculating the material equivalent electromagnetic parameter search optimization space of the current layer based on the structural equivalent parameter theory and the distribution trend of the artificial structure equivalent electromagnetic parameters;
a gene generation module: generating a material equivalent electromagnetic parameter gene of a current layer by utilizing a genetic algorithm, wherein the material equivalent electromagnetic parameter gene of the current layer is provided with a plurality of gene strings, and the number of the gene strings is the same as that of the material equivalent electromagnetic parameter of the current layer;
a genetic algorithm optimizing module: processing the material equivalent electromagnetic parameter gene by using a genetic algorithm to generate a new material equivalent electromagnetic parameter gene, simulating the generated new material equivalent electromagnetic parameter gene to generate curve data, calculating the score value of the performance of the non-uniform artificial structure equivalent electromagnetic parameter of the medium material, and determining the curve similarity distance based on the score value;
a second judging module: judging whether the curve similarity distance error is smaller than a set value or not;
an output module: outputting the optimal material equivalent electromagnetic parameter genes of each layer, inputting the optimal material equivalent electromagnetic parameter genes of each layer into an FDTD model, and simulating to obtain the equivalent electromagnetic parameters of the artificial structure with the nonuniform medium material.
8. An artificial structure equivalent electromagnetic parameter inversion system with inhomogeneous dielectric material is characterized by comprising:
a processor for executing a plurality of instructions;
a memory to store a plurality of instructions;
wherein the instructions are for storage by the memory and for loading and executing by the processor the method of artificial structure equivalent electromagnetic parameter inversion of non-uniformities in media materials according to any of claims 1-6.
9. A computer-readable storage medium having stored therein a plurality of instructions; the instructions for loading and executing by a processor the method for artificial structure equivalent electromagnetic parameter inversion of inhomogeneities in a dielectric material according to any of claims 1 to 6.
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