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

Abstract

The present application relates to a kind of electromagnetic propagation characteristics characterization and reconstruction method of heterostructure, belong to wireless communication technical field.The method adopts the thought of single layer to multiple layers, first study single layer material propagation characteristics, clear single layer material reflection and transmission ability, in combination with measured inversion material electromagnetic parameter;Then, using single layer material electromagnetic parameter, reconstruct heterostructure model by full-wave simulation, simultaneously construct multiple layer iterative propagation model based on Fresnel theory;Finally, the simulation value of reconstructed structure model propagation characteristics, the theoretical value of multiple layer iterative model and the microwave anechoic chamber measured value are compared, verify the accuracy and effectiveness of structure model and propagation model.The present application can be extended to characterize the electromagnetic propagation characteristics of various flat plate-shaped heterostructure complex structures in full-band range, and lay a theoretical foundation for structure material classification, target perception and environment twin.

Description

Technical Field

[0001] This invention belongs to the field of wireless communication technology and relates to a method for characterizing and reconstructing the electromagnetic propagation characteristics of heterogeneous structures. Background Technology

[0002] With the rapid development of wireless communication technology, the study of electromagnetic propagation characteristics of the interaction between electromagnetic waves and heterogeneous structures has become a key focus in fields such as wireless communication, sensing, and material detection. These complex materials are widely found in nature and in artificial manufacturing, such as multilayer composite materials. These structures induce complex multiple reflections, transmissions, and scattering phenomena during electromagnetic wave propagation. Accurate characterization and modeling of electromagnetic propagation characteristics have significant theoretical value and application prospects.

[0003] Traditional methods for studying electromagnetic wave propagation characteristics typically focus on simple, homogeneous media or regular structures. However, for heterogeneous, multi-layered structures, the propagation characteristics are difficult to describe accurately using traditional methods due to the complexity of materials, electromagnetic parameters, and geometry. Furthermore, in modern wireless communication, target recognition, and environmental sensing, the electromagnetic properties of complex materials have an increasingly significant impact on system performance. For example, in radar systems, the electromagnetic echo characteristics of multi-layered targets directly affect the accuracy of target recognition.

[0004] To address the propagation characteristics of heterogeneous multilayer structures, domestic scholars have simulated the reflection and scattering processes of electromagnetic waves on target surfaces using highly adjustable parameter target models combined with ray tracing techniques. However, simulation methods often face challenges such as low computational efficiency, insufficient model applicability, and a lack of experimental data support when dealing with high-frequency, broadband, and complex materials. Furthermore, a systematic analytical method for the electromagnetic response of multilayer structures is still lacking, making it difficult to effectively correlate material electromagnetic parameters with propagation characteristics.

[0005] To address the aforementioned challenges, there is an urgent need for an efficient and accurate method for characterizing and reconstructing electromagnetic propagation characteristics to overcome the shortcomings of existing methods. Summary of the Invention

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

[0007] To achieve the above objectives, the present invention provides the following technical solution:

[0008] A method for characterizing and reconstructing the electromagnetic propagation characteristics of heterogeneous structures includes the following steps:

[0009] Step 1: Study the propagation characteristics of a single-layer material in a flat plate: Measure the reflection and transmission coefficients of the single-layer material using a Vector Network Analyzer (VNA), and explore the material propagation characteristics under different frequencies, incident angles, and electromagnetic polarizations based on Fresnel theory.

[0010] Step 2: Invert the electromagnetic parameters of the single-layer material: Using the measured reflection and transmission coefficients of the single-layer material, extract the electromagnetic parameters of the single-layer material, including the relative permittivity and loss tangent.

[0011] Step 3: Reconstruct the structural model: Using the electromagnetic parameters of a single-layer material, combined with the propagation characteristics and reflection capabilities from 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 anechoic chamber to verify the performance of the structural model and propagation model;

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

[0014] Furthermore, step one specifically includes:

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

[0016] M~Θ(d n ,ε r_n ,σ n (1)

[0017] Where, d n It is the thickness of a single layer of material, ε r_n It is the relative permittivity of a single-layer material, δ n It is the loss tangent of a single-layer material;

[0018] Steps 1-2: In a microwave anechoic chamber, a dual-measurement method is used to measure the frequency domain electromagnetic propagation characteristics of the material based on a vector network analyzer. The reflection and transmission coefficients of the single-layer material are measured, and the results are expressed using R... mea and T mea express.

[0019] Furthermore, step two specifically involves:

[0020] Step Two-One: Based on the principle of the dual measurement method, S 21Defined as the ratio of the electric field intensity of the reflected signal to that of the incident signal, the reflection coefficient of a single-layer material is given by S. 21_single With ideal smooth surface material S 21_ideal The ratio represents the reflectance R of a single-layer material. single Represented as:

[0021]

[0022] Step 2-2: For single-layer materials, S 21_single Represented as:

[0023]

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

[0025] Steps two and three: When an electromagnetic wave is incident on an ideal smooth surface, total emission occurs, S 21_ideal Represented as:

[0026]

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

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

[0029]

[0030] Steps 2-5: Based on a nonlinear fitting method, the theoretical and measured values ​​of the reflection coefficient are jointly estimated under both horizontal and vertical polarization. The fitting error is defined as the cumulative mean square error between the theoretical and measured values ​​of the reflection coefficient under the two polarizations, i.e.:

[0031]

[0032] Where, N j R represents the number of angles measured, where i is the angle index and R is the number of angles measured. mea The value represents the measured reflection coefficient; in the error function (6), only ε exists. r_n A variable to be optimized is ε, which is traversed using an exhaustive search method. r_n The value of is determined, and the ε corresponding to the minimum MSE is calculated. r_nThe relative permittivity is considered the best estimate;

[0033] Steps 2-6: When an electromagnetic wave is incident perpendicularly onto a monolayer material, its propagation process includes Fresnel transmission at the air-medium interface and attenuation loss within the medium. Under perpendicular incidence (0° incident angle) conditions, the transmission coefficient of the monolayer material is approximately expressed as:

[0034]

[0035] Where, γ n The complex permittivity of a single-layer material;

[0036] Steps 2-7: To simplify the calculation, we introduce the complex refractive index k, whose real and imaginary parts satisfy the following relationship:

[0037]

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

[0039]

[0040] Furthermore, step three specifically includes:

[0041] Step 3-1: Using the electromagnetic parameters of a single-layer material, reconstruct the equivalent structural model of the planar, heterogeneous material through full-wave simulation; establish the reconstructed structural model in FEKO software, with the plane wave incident at an angle θ. i The simulation frequency range, the thickness of the reconstructed material, and the relative permittivity and loss tangent of the reconstructed structure are set by incident on the smooth surface of the reconstructed material.

[0042] Step 3-2: Using the electromagnetic parameters of a single-layer material, construct a multi-layer iterative propagation model based on Fresnel theory, and 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 γ represents the propagation direction of the nth layer. n This represents the complex permittivity of a single-layer material.

[0045] Furthermore, step four specifically includes:

[0046] Step 4-1: Verify the accuracy and effectiveness of the structural model: Compare and analyze the full-wave simulation values ​​of the reconstructed model with the measured values ​​in the microwave anechoic chamber 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 this invention are as follows: The method disclosed herein, following a single-layer to multi-layer approach, first studies the propagation characteristics of a single-layer material, clarifies its reflection and transmission capabilities, and inverts the material's electromagnetic parameters using measured data. Then, using these single-layer material electromagnetic parameters, it reconstructs a model of a heterogeneous structure through full-wave simulation, while simultaneously constructing 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 across the entire frequency range, avoiding the computational complexity and accuracy issues of traditional methods. It possesses 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 invention will be set forth in part in the description which follows, and in part will be apparent to those skilled in the art from the following examination, or may be learned from practice of the invention. The objectives and other advantages of the invention can be realized and obtained through the following description. Attached Figure Description

[0050] To make the objectives, technical solutions, and advantages of the present invention clearer, the preferred embodiments of the present invention will be described in detail below with reference to the accompanying drawings, wherein:

[0051] Figure 1 This is a schematic diagram of radio wave propagation in a multi-layered structure.

[0052] Figure 2 This is a schematic diagram of a microwave anechoic chamber measurement.

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

[0054] Figure 4 Here is a flowchart of the full-wave simulation verification scheme;

[0055] Figure 5 This is a schematic diagram of a multi-level iterative propagation model based on Fresnel theory.

[0056] Figure 6 These are simulation values ​​from a multi-layer iterative propagation model based on Fresnel theory and actual measured values ​​from a microwave anechoic chamber. Detailed Implementation

[0057] The following specific examples illustrate the implementation of the present invention. Those skilled in the art can easily understand other advantages and effects of the present invention from the content disclosed in this specification. The present invention can also be implemented or applied through other different specific embodiments, and various details in this specification can be modified or changed 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 are only schematic representations of the basic concept of the present invention. Unless otherwise specified, the following embodiments and features can be combined with each other.

[0058] The accompanying drawings are for illustrative purposes only and are schematic diagrams, not actual pictures. They should not be construed as limiting the invention. To better illustrate the embodiments of the invention, some parts in the drawings may be omitted, enlarged, or reduced, and do not represent the actual product dimensions. It is understandable to those skilled in the art that some well-known structures and their descriptions may be omitted in the drawings.

[0059] In the accompanying drawings of the embodiments of the present invention, the same or similar reference numerals correspond to the same or similar components. In the description of the present invention, it should be understood that if terms such as "upper," "lower," "left," "right," "front," and "rear" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings, they are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, the terms used to describe positional relationships in the drawings are only for illustrative purposes and should not be construed as limiting the present invention. For those skilled in the art, the specific meaning of the above terms can be understood according to the specific circumstances.

[0060] Figure 1 This is a schematic diagram of electromagnetic wave propagation in a multi-layer structure, Example 1. This example adopts a single-layer to multi-layer approach. First, the propagation characteristics of a single-layer material are studied to clarify its reflection and transmission capabilities, and the electromagnetic parameters of the material are inverted based on measured data. Then, using the electromagnetic parameters of the single-layer material, a heterogeneous structure model is reconstructed through full-wave simulation, while simultaneously constructing a multi-layer iterative propagation model based on Fresnel theory. Finally, the simulated values ​​of the propagation characteristics of the reconstructed structural model, the theoretical values ​​of the multi-layer iterative model, and the measured values ​​in a microwave anechoic chamber 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 a single-layer material in a flat plate: Measure the reflection and transmission coefficients of the single-layer material using a Vector Network Analyzer (VNA). Based on Fresnel theory, explore the material propagation characteristics under different frequencies, incident angles, and electromagnetic polarizations.

[0062] Step 2: Invert the electromagnetic parameters of the single-layer material: Using the measured reflection and transmission coefficients of the single-layer material, extract the electromagnetic parameters of the single-layer material, including the relative permittivity 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 from 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 anechoic chamber to verify the performance of the structural model and propagation model.

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

[0066] The first step is as follows:

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

[0068] M~Θ(d n ,ε r_n ,σ n (29)

[0069] Where, d n It is the thickness of a single layer of material, ε r_n It is the relative permittivity of a single-layer material, δ n It is the loss tangent of a single-layer material.

[0070] Steps 1-2: In a microwave anechoic chamber, a dual-measurement method is used to measure the frequency domain electromagnetic propagation characteristics of the material based on a vector network analyzer. The reflection and transmission coefficients of the single-layer material are measured, and the results are expressed using R... mea and T mea express.

[0071] Figure 2 This is a schematic diagram of a microwave anechoic chamber measurement. Figure 3 A flowchart illustrating the method for characterizing and reconstructing the propagation characteristics of electromagnetic waves interacting with complex materials.

[0072] The second step is specifically as follows:

[0073] Step Two-One: Based on the principle of the dual measurement method, S 21 Defined as the ratio of the electric field intensity of the reflected signal to that of the incident signal, the reflection coefficient of a single-layer material is given by S. 21_singleWith ideal smooth surface material S 21_ideal The ratio represents the reflectance R of a single-layer material. single Represented as:

[0074]

[0075] Step 2-2: For single-layer materials, S 21_single Represented as:

[0076]

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

[0078] Steps two and three: When an electromagnetic wave is incident on an ideal smooth surface, total emission occurs, S 21_ideal It can be represented as:

[0079]

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

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

[0082]

[0083] Steps 2-5: Based on a nonlinear fitting method, the theoretical and measured values ​​of the reflection coefficient are jointly estimated under both horizontal and vertical polarization. The fitting error is defined as the cumulative mean square error between the theoretical and measured values ​​of the reflection coefficient under the two polarizations, i.e.:

[0084]

[0085] Where, N j R represents the number of angles measured, where i is the angle index and R is the number of angles measured. mea The value represents the measured reflection coefficient; in the error function (6), only ε exists. r_n A variable to be optimized is ε, which is traversed using an exhaustive search method. r_n The value of is determined, and the ε corresponding to the minimum MSE is calculated. r_n The relative permittivity is considered the best estimate.

[0086] Steps 2-6: When an electromagnetic wave is incident perpendicularly onto a monolayer material, its propagation process includes Fresnel transmission at the air-medium interface and attenuation loss within the medium. Under perpendicular incidence (0° incident angle) conditions, the transmission coefficient of the monolayer material can be approximately expressed as:

[0087]

[0088] Where, γ n This represents the complex permittivity of a single-layer material.

[0089] Steps 2-7: To simplify the calculation, we introduce the complex refractive index k, whose real and imaginary parts satisfy the following relationship:

[0090]

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

[0092]

[0093] Step three specifically refers to:

[0094] Step 3-1: Using the electromagnetic parameters of a single-layer material, reconstruct the equivalent structural model of the planar, heterogeneous material through full-wave simulation. Establish the reconstructed structural model in FEKO software, with the plane wave incident at an angle θ. i The simulation frequency range, the thickness of the reconstructed material, and the relative permittivity and loss tangent of the reconstructed structure are set by incident on the smooth surface of the reconstructed material. Figure 4 This is a flowchart of the full-wave simulation scheme.

[0095] Step 3-2: Using the electromagnetic parameters of a single-layer material, construct a multi-layer iterative propagation model based on Fresnel theory, and 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 γ represents the propagation direction of the nth layer. n This represents the complex permittivity of a single-layer material. Figure 5 This is a schematic diagram of a multi-level iterative propagation model based on Fresnel theory.

[0098] The fourth step is specifically as follows:

[0099] Step 4-1: Verify the accuracy and effectiveness of the structural model: Compare and analyze the full-wave simulation values ​​of the reconstructed model with the measured values ​​in the microwave anechoic chamber 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 simulation values ​​from a multi-layer iterative propagation model based on Fresnel theory and actual measured values ​​from a microwave anechoic chamber.

[0101] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit it. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the spirit and scope of the present invention, and all such modifications or substitutions should be covered within the scope of the claims of the present invention.

Claims

1. A method for characterizing and reconstructing the electromagnetic propagation characteristics of heterogeneous structures, characterized in that: Includes the following steps: Step 1: Study the propagation characteristics of a single-layer material in a flat plate: The reflection and transmission coefficients of the single-layer material are measured using a vector network analyzer (VNA). Based on Fresnel theory, the propagation characteristics of the material under different frequencies, different incident angles, and different electromagnetic polarizations are investigated. Step 2: Invert the electromagnetic parameters of the single-layer material: Using the measured reflection and transmission coefficients of the single-layer material, extract the electromagnetic parameters of the single-layer material, including the relative permittivity and loss tangent. Step 3: Reconstruct the structural model: Using the electromagnetic parameters of a single-layer material, combined with the propagation characteristics and reflection capabilities from 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 anechoic chamber to verify the performance of the structural model and propagation model; Step 5: Complete the electromagnetic propagation characteristics of the flat, irregularly shaped, heterogeneous material structure: output the reflection and transmission characteristics of the reconstructed structure; Step two specifically involves: Step Two-One: Based on the principle of the dual measurement method, S 21 Defined as the ratio of the electric field intensity of the reflected signal to that of the incident signal, the reflection coefficient of a single-layer material is given by S. 21_single With ideal smooth surface material S 21_ideal The ratio represents the reflectance R of a single-layer material. single Represented as: Step 2-2: For single-layer materials, S 21_single Represented as: Among them, G T and G R Representing the gains of the transmitting and receiving antennas respectively, |R| and |T| are the Fresnel reflection and transmission coefficients respectively, and d i ψ is the distance from the electromagnetic wave incident from the transmitting antenna to the surface of the material, β is the additional phase shift, and β represents the attenuation loss inside the single-layer material. Steps two and three: When an electromagnetic wave is incident on an ideal smooth surface, total emission occurs, S 21ideal Represented as: Among them, |R ideal | represents the Fresnel reflection coefficient of an ideal smooth surface material, which is approximately 1; Steps 2-4: Substituting formulas (3) and (4) into formula (2), the reflection coefficient of a single-layer material is expressed as: Steps 2-5: Based on a nonlinear fitting method, the theoretical and measured values ​​of the reflection coefficient are jointly estimated under both horizontal and vertical polarization. The fitting error is defined as the cumulative mean square error between the theoretical and measured values ​​of the reflection coefficient under the two polarizations, i.e.: Where, N j R represents the number of angles measured, where i is the angle index and R is the number of angles measured. mea The value represents the measured reflection coefficient; in the error function (6), only ε exists. r_n A variable to be optimized is ε, which is traversed using an exhaustive search method. r_n The value of is determined, and the ε corresponding to the minimum MSE is calculated. r_n The relative permittivity is considered the best estimate; Steps 2-6: When an electromagnetic wave is incident perpendicularly onto a monolayer material, its propagation process includes Fresnel transmission at the air-medium interface and attenuation loss within the medium. Under perpendicular incidence (0° incident angle) conditions, the transmission coefficient of the monolayer material is approximately expressed as: Where, γ n The complex permittivity of a single-layer material; Steps 2-7: To simplify the calculation, we introduce the complex refractive index k, whose real and imaginary parts satisfy the following relationship: Steps 2-8: Calculate the loss tangent of a single-layer material according to formulas (7) and (8): Step three specifically involves: Step 3-1: Using the electromagnetic parameters of a single-layer material, reconstruct the equivalent structural model of the planar, heterogeneous material through full-wave simulation; establish the reconstructed structural model in FEKO software, with the plane wave incident at an angle θ. i The simulation frequency range, the thickness of the reconstructed material, and the relative permittivity and loss tangent of the reconstructed structure are set by incident on the smooth surface of the reconstructed material. Step 3-2: Using the electromagnetic parameters of a single-layer material, construct a multi-layer iterative propagation model based on Fresnel theory, and evaluate the reflection characteristics of the reconstructed structure model at different frequencies and incident angles, expressed as: Among them, Q n+1 =1,E n+1 =0,F n+1 =1,G n+1 =1,θ n γ represents the propagation direction of the nth layer. n This represents the complex permittivity of a single-layer material.

2. The method for characterizing and reconstructing the electromagnetic propagation characteristics of heterogeneous structures according to claim 1, characterized in that: step one specifically comprises: Step 1-1: Define M as a flat composite structure composed of multiple layers of materials; for n layers of materials, M is represented as: M~Θ(d n ,he r_n ,s n (1) in, d n It is the thickness of a single layer of material, ε r_n It is the relative permittivity of a single-layer material, δ n It is the loss tangent of a single-layer material; Steps 1-2: In a microwave anechoic chamber, a dual-measurement method is used to measure the frequency domain electromagnetic propagation characteristics of the material based on a vector network analyzer. The reflection and transmission coefficients of the single-layer material are measured, and the results are expressed using R... mea and T mea express.

3. The method for characterizing and reconstructing the electromagnetic propagation characteristics of a heterogeneous structure according to claim 1, characterized in that: step four specifically comprises: Step 4-1: Verify the accuracy and effectiveness of the structural model: Compare and analyze the full-wave simulation values ​​of the reconstructed model with the measured values ​​in the microwave anechoic chamber 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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