Electromagnetic propagation characteristic representation and reconstruction method of special-shaped heterostructure

Abstract

The invention relates to an electromagnetic propagation characteristic characterization and reconstruction method of a special-shaped heterostructure, and belongs to the technical field of wireless communication. The method adopts a single-layer to multi-layer thought, and comprises the following steps: firstly, researching the propagation characteristics of a single-layer material, determining the reflection and transmission capabilities of the single-layer material, and inverting electromagnetic parameters of the material in combination with actual measurement; secondly, reconstructing a special-shaped heterostructure model through full-wave simulation by utilizing the electromagnetic parameters of the single-layer material, and constructing a multilayer iterative propagation model based on the Fresnel theory; and finally, comparing the reconstructed propagation characteristic simulation value of the structure model and the theoretical value of the multi-layer iterative model with the measured value of the anechoic chamber, and verifying the accuracy and effectiveness of the structure model and the propagation model. The method can be expanded to be used for representing electromagnetic propagation characteristics of various flat plate type special-shaped heterogeneous complex structures in a full frequency band range, and a theoretical foundation is laid for structural material classification, target perception and environment twinborn.

Description

Technical Field

[0001] The present invention belongs to the technical field of wireless communications and relates to a method for characterizing and reconstructing electromagnetic propagation characteristics of a heterogeneous structure. Background Art

[0002] With the rapid development of wireless communication technology, the study of electromagnetic propagation characteristics of electromagnetic waves interacting with heterogeneous structures has become a focus of attention in the fields of wireless communication, perception, and material detection. These complex materials are widely present in nature and artificial manufacturing, such as multi-layer composite materials. These structures will cause complex multiple reflections, multiple transmissions, and scattering phenomena during the propagation of electromagnetic waves. Accurately characterizing and modeling electromagnetic propagation characteristics has important theoretical value and application prospects.

[0003] Traditional research methods for electromagnetic wave propagation characteristics are usually carried out for simple uniform media or regular structures. However, for heterogeneous multilayer structures, the propagation characteristics are difficult to accurately describe using traditional methods due to the complexity of materials, electromagnetic parameters and geometric shapes. In addition, in modern wireless communications, target recognition, environmental perception and other fields, the electromagnetic characteristics of complex materials have an increasingly significant impact on system performance. For example, in radar systems, the electromagnetic echo characteristics of multilayer targets are directly related to the accuracy of target recognition.

[0004] Aiming at the propagation characteristics of heterogeneous multilayer structures with special shapes, domestic scholars have simulated the reflection and scattering process of electromagnetic waves on the target surface by using a highly adjustable parameter target model combined with ray tracing technology. However, when dealing with high-frequency bands, wide-bandwidth and complex materials, simulation methods often face problems such as low computational efficiency, insufficient model applicability and lack of experimental data support. At the same time, the electromagnetic response law of multilayer structures still lacks a systematic analysis method, making it difficult to effectively associate the electromagnetic parameters of materials with propagation characteristics.

[0005] In response to the above challenges, an efficient and accurate method for characterizing and reconstructing electromagnetic propagation characteristics is urgently needed to make up for the shortcomings of existing methods. Summary of the invention

[0006] In view of this, an object of the present invention is to provide a method for characterizing and reconstructing the electromagnetic propagation characteristics of heterogeneous structures.

[0007] In order to achieve the above object, the present invention provides the following technical solutions:

[0008] A method for characterizing and reconstructing electromagnetic propagation characteristics of a heterogeneous structure, comprising the following steps:

[0009] Step 1: Study the propagation characteristics of flat single-layer materials: Use a vector network analyzer (VNA) to measure the reflection coefficient and transmission coefficient of the single-layer material, and based on Fresnel theory, explore the propagation characteristics of the material under different frequencies, different incident angles, and different radio wave polarizations;

[0010] Step 2: Invert the electromagnetic parameters of the single-layer material: Use the measured reflection coefficient and transmission coefficient values ​​of the single-layer material to extract the electromagnetic parameters of the single-layer material, including relative dielectric constant and loss tangent;

[0011] Step 3: Reconstruct the structural model: Using the electromagnetic parameters of the single-layer material, combined with the propagation characteristics and reflection capabilities in step 1, an equivalent material structure model is reconstructed through full-wave simulation. At the same time, based on the single-layer propagation model, a multi-layer iterative propagation model based on Fresnel theory is established;

[0012] Step 4: Verify the accuracy and effectiveness of the structural model and propagation model: Compare and analyze the simulated values ​​of the propagation characteristics of the reconstructed equivalent structural model, the theoretical values ​​of the multi-layer iterative model and the measured values ​​in the microwave darkroom to verify the performance of the structural model and propagation model;

[0013] Step 5: Complete the electromagnetic propagation characteristics of the flat-type special-shaped heterogeneous material structure: output the reflection and transmission characteristics of the reconstructed structure.

[0014] Further, the step 1 is specifically as follows:

[0015] Step 1-1: Define M as a flat composite structure composed of multiple layers of material; for n layers of material, M is expressed as:

[0016] M~Θ(d n ,ε r_n ,σ n )(1)

[0017] Among them, d n is the thickness of a single layer of material, ε r_n is the relative dielectric constant of the single layer material, δ n is the loss tangent of a single layer of material;

[0018] Step 1-2: In a microwave darkroom, the dual measurement method is used to carry out the frequency domain material electromagnetic propagation characteristic measurement based on the vector network analyzer to obtain the reflection coefficient and transmission coefficient measurement values ​​of the single-layer material. The measurement results are respectively expressed as R mea and T mea express.

[0019] Further, the step 2 is specifically as follows:

[0020] Step 2-1: Based on the principle of double measurement, S 21Defined as the ratio of the electric field strength of the reflected signal to the incident signal, the reflection coefficient of a single layer of material is given by S 21_single With ideal smooth surface material S 21_ideal The reflection coefficient R of a single layer of material is expressed as single It is expressed as:

[0021]

[0022] Step 2-2: For a single layer material, S 21_single It is expressed as:

[0023]

[0024] Among them, G T and G R Represent the gains of the transmitting antenna and the receiving antenna respectively, |R| and |T| are the Fresnel reflection coefficient and transmission coefficient respectively, d i is the distance from the transmitting antenna to the surface of the material, ψ is the additional phase shift, and β represents the attenuation loss inside the single-layer material;

[0025] Step 2-3: When electromagnetic waves are incident on an ideal smooth surface, total reflection occurs, S 21_ideal It is expressed as:

[0026]

[0027] Among them, |R ideal | represents the Fresnel reflection coefficient of an ideal smooth surface material, which is approximately 1;

[0028] Step 2-4: Substituting formula (3) and (4) into formula (2), the reflection coefficient of a single layer of material is expressed as:

[0029]

[0030] Steps 2-5: Based on the nonlinear fitting method, the theoretical and measured values ​​of the reflection coefficient are jointly estimated under horizontal and vertical polarizations; the fitting error is defined as the cumulative value of the mean square error between the theoretical and measured values ​​of the reflection coefficient under the two polarizations, that is:

[0031]

[0032] Among them, N j is the number of measured angles, i is the measured angle serial number, R mea represents the measured value of the reflection coefficient; in the error function (6), only ε r_n A variable to be optimized, traversing ε by exhaustive method r_n The value of ε corresponding to the minimum MSE r_nThe relative permittivity is considered as the best estimate;

[0033] Step 2-6: When the electromagnetic wave is incident vertically on a single-layer material, its propagation process includes Fresnel transmission at the interface between air and medium and attenuation loss inside the medium; under vertical incidence (0° incidence angle), the transmission coefficient of the single-layer material is approximately expressed as:

[0034]

[0035] Among them, γ n Represents the complex dielectric constant of a single layer of material;

[0036] Step 2-7: In order to simplify the calculation, the complex refractive index k is introduced, and the real part and the imaginary part satisfy the following relationship:

[0037]

[0038] Step 2-8: Calculate the loss tangent of a single layer of material using formulas (7) and (8):

[0039]

[0040] Further, the step three is specifically as follows:

[0041] Step 3-1: Using the electromagnetic parameters of the single-layer material, reconstruct the equivalent structural model of the flat-type heterogeneous material through full-wave simulation; establish the reconstructed structural model in the FEKO software, and the plane wave is incident at an angle of θ i The incident light is directed onto the smooth surface of the reconstructed material, and the simulation frequency range, thickness of the reconstructed material, and relative dielectric constant and loss tangent of the reconstructed structure are set;

[0042] Step 3-2: Using the electromagnetic parameters of a single-layer material, a multi-layer iterative propagation model based on Fresnel theory is constructed to evaluate the reflection characteristics of the reconstructed structure model at different frequencies and incident angles, expressed as:

[0043]

[0044] Among them, Q n+1 =1,E n+1 =0, F n+1 =1, G n+1 =1,θ n Represents the propagation direction of the nth layer, γ n Represents the complex dielectric constant of a single layer of material.

[0045] Further, the step 4 is specifically as follows:

[0046] Step 4-1: Verify the accuracy and effectiveness of the structural model: Compare and analyze the full-wave simulation value of the reconstructed model with the actual measured value in the microwave darkroom to verify the rationality and applicability of the reconstructed structural model;

[0047] Step 4-2: Verify the accuracy and effectiveness of the propagation model: Compare the theoretical values ​​of the multi-layer iterative model with the measured values ​​in the microwave anechoic chamber, and evaluate the accuracy and reliability of the propagation model based on the relative error.

[0048] The beneficial effects of the present invention are as follows: the method disclosed in the present invention, with the idea of ​​single-layer to multi-layer, first studies the propagation characteristics of single-layer materials, clarifies the reflection and transmission capabilities of single-layer materials, and combines the measured inversion of material electromagnetic parameters; then, using the electromagnetic parameters of single-layer materials, reconstructs the heterogeneous structure model through full-wave simulation, and constructs a multi-layer iterative propagation model based on Fresnel theory. This method can be extended to characterize the electromagnetic propagation characteristics of various heterogeneous and complex materials in the full frequency band, avoiding the computational complexity and accuracy problems in traditional methods, and has strong adaptability and scalability, laying a theoretical foundation for structural material classification, target perception and environmental twinning.

[0049] Other advantages, objectives and features of the present invention will be described in the following description to some extent, and to some extent, will be obvious to those skilled in the art based on the following examination and study, or can be taught from the practice of the present invention. The objectives and other advantages of the present invention can be realized and obtained through the following description. BRIEF DESCRIPTION OF THE DRAWINGS

[0050] In order to make the purpose, technical solutions and advantages of the present invention more clear, the present invention will be described in detail below in conjunction with the accompanying drawings, wherein:

[0051] Figure 1 It is a schematic diagram of radio wave propagation in a multi-layer structure;

[0052] Figure 2 This is a schematic diagram of microwave darkroom measurement;

[0053] Figure 3 A flow chart of the method for characterizing and reconstructing the propagation characteristics of electromagnetic waves interacting with complex materials;

[0054] Figure 4 This is the flow chart of the full-wave simulation verification solution;

[0055] Figure 5 It is a schematic diagram of a multi-layer iterative propagation model based on Fresnel theory;

[0056] Figure 6 These are the simulation values ​​of the multi-layer iterative propagation model based on Fresnel theory and the actual measurement values ​​in the microwave darkroom. DETAILED DESCRIPTION

[0057] The following describes the embodiments of the present invention by specific examples, and those skilled in the art can easily understand other advantages and effects of the present invention from the contents disclosed in this specification. The present invention can also be implemented or applied through other different specific embodiments, and the details in this specification can also be modified or changed in various ways based on different viewpoints and applications without departing from the spirit of the present invention. It should be noted that the illustrations provided in the following embodiments only illustrate the basic concept of the present invention in a schematic manner, and the following embodiments and features in the embodiments can be combined with each other without conflict.

[0058] Among them, the drawings are only used for illustrative explanations, and they only represent schematic diagrams rather than actual pictures, and should not be understood as limitations on the present invention. In order to better illustrate the embodiments of the present invention, some parts of the drawings may be omitted, enlarged or reduced, and do not represent the size of actual products. For those skilled in the art, it is understandable that some well-known structures and their descriptions in the drawings may be omitted.

[0059] The same or similar numbers in the drawings of the embodiments of the present invention correspond to the same or similar parts; in the description of the present invention, it should be understood that if the terms "upper", "lower", "left", "right", "front", "rear", etc. indicate the orientation or position relationship, they are based on the orientation or position relationship shown in the drawings, which is only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operate in a specific orientation. Therefore, the terms describing the position relationship in the drawings are only used for illustrative purposes and cannot be understood as limiting the present invention. For ordinary technicians in this field, the specific meanings of the above terms can be understood according to specific circumstances.

[0060] Figure 1 The schematic diagram of radio wave propagation in a multi-layer structure is shown in Example 1. This example adopts the idea of ​​single-layer to multi-layer. First, the propagation characteristics of a single-layer material are studied, the reflection and transmission capabilities of a single-layer material are clarified, and the electromagnetic parameters of the material are inverted in combination with the measured values. Then, the electromagnetic parameters of the single-layer material are used to reconstruct the model of the heterogeneous structure through full-wave simulation, and a multi-layer iterative propagation model based on Fresnel theory is constructed at the same time. Finally, the propagation characteristics simulation value of the reconstructed structural model, the theoretical value of the multi-layer iterative model, and the measured value in the microwave darkroom are compared to verify the accuracy and effectiveness of the structural model and the propagation model. The specific steps are as follows:

[0061] Step 1: Study the propagation characteristics of flat single-layer materials: Measure the reflection coefficient and transmission coefficient of the single-layer material based on the Vector Network Analyzer (VNA), and based on the Fresnel theory, explore the propagation characteristics of the material under different frequencies, different incident angles and different radio wave polarizations.

[0062] Step 2: Invert the electromagnetic parameters of the single-layer material: Use the measured reflection coefficient and transmission coefficient values ​​of the single-layer material to extract the electromagnetic parameters of the single-layer material, including relative dielectric constant and loss tangent.

[0063] Step 3: Reconstruct the structural model: Using the electromagnetic parameters of a single-layer material, combined with the propagation characteristics and reflection capabilities in step 1, an equivalent material structure model is reconstructed through full-wave simulation. At the same time, based on the single-layer propagation model, a multi-layer iterative propagation model based on Fresnel theory is established.

[0064] Step 4: Verify the accuracy and effectiveness of the structural model and propagation model: Compare and analyze the simulated values ​​of the propagation characteristics of the reconstructed equivalent structural model, the theoretical values ​​of the multi-layer iterative model and the measured values ​​in the microwave darkroom to verify the performance of the structural model and propagation model.

[0065] Step 5: Complete the electromagnetic propagation characteristics of the flat-type special-shaped heterogeneous material structure: output the reflection and transmission characteristics of the reconstructed structure.

[0066] The step 1 is specifically as follows:

[0067] Step 1-1: Define M as a flat composite structure composed of multiple layers of material. Taking n layers of material as an example, M can be expressed as:

[0068] M~Θ(d n ,ε r_n ,σ n )(29)

[0069] Among them, d n is the thickness of a single layer of material, ε r_n is the relative dielectric constant of the single layer material, δ n is the loss tangent of a single layer of material.

[0070] Step 1-2: In a microwave darkroom, the dual measurement method is used to carry out the frequency domain material electromagnetic propagation characteristic measurement based on the vector network analyzer to obtain the reflection coefficient and transmission coefficient measurement values ​​of the single-layer material. The measurement results are respectively expressed as R mea and T mea express.

[0071] Figure 2 This is a schematic diagram of microwave darkroom measurement; Figure 3 Flowchart of the method for characterizing and reconstructing the propagation characteristics of electromagnetic waves interacting with complex materials.

[0072] The step 2 is specifically as follows:

[0073] Step 2-1: Based on the principle of double measurement, S 21 Defined as the ratio of the electric field strength of the reflected signal to the incident signal, the reflection coefficient of a single layer of material is given by S 21_singleWith ideal smooth surface material S 21_ideal The reflection coefficient R of a single layer of material is expressed as single It is expressed as:

[0074]

[0075] Step 2-2: For a single layer material, S 21_single It is expressed as:

[0076]

[0077] Among them, G T and G R Represent the gains of the transmitting antenna and the receiving antenna respectively, |R| and |T| are the Fresnel reflection coefficient and transmission coefficient respectively, d i is the distance from the transmitting antenna to the surface of the material, ψ is the additional phase shift, and β represents the attenuation loss inside the single-layer material;

[0078] Step 2-3: When electromagnetic waves are incident on an ideal smooth surface, total reflection occurs, S 21_ideal It can be expressed as:

[0079]

[0080] Among them, |R ideal | represents the Fresnel reflection coefficient of an ideal smooth surface material, which can be approximated to 1 in theory;

[0081] Step 2-4: Substituting formula (31) and (32) into formula (30), the reflection coefficient of the single-layer material is expressed as:

[0082]

[0083] Steps 2-5: Based on the nonlinear fitting method, the theoretical and measured values ​​of the reflection coefficient are jointly estimated under horizontal and vertical polarizations; the fitting error is defined as the cumulative value of the mean square error between the theoretical and measured values ​​of the reflection coefficient under the two polarizations, that is:

[0084]

[0085] Among them, N j is the number of measured angles, i is the measured angle serial number, R mea represents the measured value of the reflection coefficient; in the error function (6), only ε r_n A variable to be optimized, traversing ε by exhaustive method r_n The value of ε corresponding to the minimum MSE r_n The relative permittivity is considered as the best estimate.

[0086] Step 2-6: When the electromagnetic wave is incident vertically on a single-layer material, its propagation process includes Fresnel transmission at the interface between air and medium and attenuation loss inside the medium. Under vertical incidence (0° incidence angle), the transmission coefficient of the single-layer material can be approximately expressed as:

[0087]

[0088] Among them, γ n Represents the complex dielectric constant of a single layer of material.

[0089] Step 2-7: In order to simplify the calculation, the complex refractive index k is introduced, and the real part and the imaginary part satisfy the following relationship:

[0090]

[0091] Step 2-8: Calculate the loss tangent of a single layer of material according to formulas (21) and (22):

[0092]

[0093] The step three is specifically as follows:

[0094] Step 3-1: Use the electromagnetic parameters of the single-layer material to reconstruct the equivalent structural model of the flat-type heterogeneous material through full-wave simulation. Establish the reconstructed structural model in FEKO software, and the plane wave is incident at an angle of θ i The signal is incident on the smooth surface of the reconstructed material, and the simulation frequency range, thickness of the reconstructed material, and relative permittivity and loss tangent of the reconstructed structure are set. Figure 4 This is the flow chart of the full-wave simulation solution.

[0095] Step 3-2: Using the electromagnetic parameters of a single-layer material, a multi-layer iterative propagation model based on Fresnel theory is constructed to evaluate the reflection characteristics of the reconstructed structure model at different frequencies and incident angles, expressed as:

[0096]

[0097] Among them, Q n+1 =1,E n+1 =0, F n+1 =1, G n+1 =1,θ n Represents the propagation direction of the nth layer, γ n Represents the complex dielectric constant of a single layer of material. Figure 5 It is a schematic diagram of a multi-layer iterative propagation model based on Fresnel theory;

[0098] The step 4 is specifically as follows:

[0099] Step 4-1: Verify the accuracy and effectiveness of the structural model: Compare and analyze the full-wave simulation value of the reconstructed model with the actual measured value in the microwave darkroom to verify the rationality and applicability of the reconstructed structural model.

[0100] Step 4-2: Verify the accuracy and effectiveness of the propagation model: Compare the theoretical values ​​of the multi-layer iterative model with the measured values ​​in the microwave anechoic chamber, and evaluate the accuracy and reliability of the propagation model based on the relative error. Figure 6 These are the simulation values ​​of the multi-layer iterative propagation model based on Fresnel theory and the actual measurement values ​​in the microwave darkroom.

[0101] Finally, it should be noted that the above embodiments are only used to illustrate the technical solution of the present invention rather than to limit it. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical solution of the present invention can be modified or replaced by equivalents without departing from the purpose and scope of the technical solution, which should be included in the scope of the claims of the present invention.

Claims

1. A method for characterizing and reconstructing electromagnetic propagation characteristics of heterogeneous structures, characterized by: The following steps are involved: Step 1: Study the propagation characteristics of flat single-layer materials: Use a vector network analyzer (VNA) to measure the reflection coefficient and transmission coefficient of the single-layer material, and based on Fresnel theory, explore the propagation characteristics of the material under different frequencies, different incident angles, and different radio wave polarizations; Step 2: Invert the electromagnetic parameters of the single-layer material: Use the measured reflection coefficient and transmission coefficient values ​​of the single-layer material to extract the electromagnetic parameters of the single-layer material, including relative dielectric constant and loss tangent; Step 3: Reconstruct the structural model: Using the electromagnetic parameters of the single-layer material, combined with the propagation characteristics and reflection capabilities in step 1, an equivalent material structure model is reconstructed through full-wave simulation. At the same time, based on the single-layer propagation model, a multi-layer iterative propagation model based on Fresnel theory is established; Step 4: Verify the accuracy and effectiveness of the structural model and propagation model: Compare and analyze the simulated values ​​of the propagation characteristics of the reconstructed equivalent structural model, the theoretical values ​​of the multi-layer iterative model and the measured values ​​in the microwave darkroom to verify the performance of the structural model and propagation model; Step 5: Complete the electromagnetic propagation characteristics of the flat-type special-shaped heterogeneous material structure: output the reflection and transmission characteristics of the reconstructed structure.

2. The method for characterizing and reconstructing electromagnetic propagation characteristics of a heterogeneous structure according to claim 1, characterized in that: the step 1 is specifically: Step 1-1: Define M as a flat composite structure composed of multiple layers of material; for n layers of material, M is expressed as: M~Θ(d n ,he r_n ,s n (1) in, d n is the thickness of a single layer of material, ε r_n is the relative dielectric constant of the single layer material, δ n is the loss tangent of a single layer of material; Step 1-2: In a microwave darkroom, the dual measurement method is used to carry out the frequency domain material electromagnetic propagation characteristic measurement based on the vector network analyzer to obtain the reflection coefficient and transmission coefficient measurement values ​​of the single-layer material. The measurement results are respectively expressed as R mea and T mea express.

3. The method for characterizing and reconstructing electromagnetic propagation characteristics of a heterogeneous structure according to claim 1, characterized in that: the step 2 is specifically: Step 2-1: Based on the principle of double measurement, S 21 Defined as the ratio of the electric field strength of the reflected signal to the incident signal, the reflection coefficient of a single layer of material is given by S 21_single With ideal smooth surface material S 21_ideal The reflection coefficient R of a single layer of material is expressed as single It is expressed as: Step 2-2: For a single layer material, S 21_single It is expressed as: in, G T and G R Represent the gains of the transmitting antenna and the receiving antenna respectively, |R| and |T| are the Fresnel reflection coefficient and transmission coefficient respectively, d i is the distance from the transmitting antenna to the surface of the material, ψ is the additional phase shift, and β represents the attenuation loss inside the single-layer material; Step 2-3: When electromagnetic waves are incident on an ideal smooth surface, total reflection occurs, S 21_ideal It is expressed as: Among them, |R ideal | represents the Fresnel reflection coefficient of an ideal smooth surface material, which is approximately 1; Step 2-4: Substituting formula (3) and (4) into formula (2), the reflection coefficient of a single layer of material is expressed as: Steps 2-5: Based on the nonlinear fitting method, the theoretical and measured values ​​of the reflection coefficient are jointly estimated under horizontal and vertical polarizations; the fitting error is defined as the cumulative value of the mean square error between the theoretical and measured values ​​of the reflection coefficient under the two polarizations, that is: Among them, N j is the number of measured angles, i is the measured angle serial number, R mea represents the measured value of the reflection coefficient; in the error function (6), only ε r_n A variable to be optimized, traversing ε by exhaustive method r_n The value of ε corresponding to the minimum MSE r_n The relative permittivity is considered as the best estimate; Step 2-6: When the electromagnetic wave is incident vertically on a single-layer material, its propagation process includes Fresnel transmission at the interface between air and medium and attenuation loss inside the medium; under vertical incidence (0° incidence angle), the transmission coefficient of the single-layer material is approximately expressed as: Among them, γ n Represents the complex dielectric constant of a single layer of material; Step 2-7: In order to simplify the calculation, the complex refractive index k is introduced, and the real part and the imaginary part satisfy the following relationship: Step 2-8: Calculate the loss tangent of a single layer of material using formulas (7) and (8):

4. The method for characterizing and reconstructing electromagnetic propagation characteristics of a heterogeneous structure according to claim 1, characterized in that: the step three is specifically: Step 3-1: Using the electromagnetic parameters of the single-layer material, reconstruct the equivalent structural model of the flat-type heterogeneous material through full-wave simulation; establish the reconstructed structural model in the FEKO software, and the plane wave is incident at an angle of θ i The incident light is directed onto the smooth surface of the reconstructed material, and the simulation frequency range, thickness of the reconstructed material, and relative dielectric constant and loss tangent of the reconstructed structure are set; Step 3-2: Using the electromagnetic parameters of a single-layer material, a multi-layer iterative propagation model based on Fresnel theory is constructed to evaluate the reflection characteristics of the reconstructed structure model at different frequencies and incident angles, expressed as: in, Q n+1 =1,E n+1 =0, F n+1 =1, G n+1 =1,θ n Represents the propagation direction of the nth layer, γ n Represents the complex dielectric constant of a single layer of material.

5. The method for characterizing and reconstructing electromagnetic propagation characteristics of a heterogeneous structure according to claim 1, characterized in that: the step 4 is specifically: Step 4-1: Verify the accuracy and effectiveness of the structural model: Compare and analyze the full-wave simulation value of the reconstructed model with the actual measured value in the microwave darkroom to verify the rationality and applicability of the reconstructed structural model; Step 4-2: Verify the accuracy and effectiveness of the propagation model: Compare the theoretical values ​​of the multi-layer iterative model with the measured values ​​in the microwave anechoic chamber, and evaluate the accuracy and reliability of the propagation model based on the relative error.

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