A design method of wave-absorbing material based on fractal geometry

Abstract

The application provides a design method of a wave-absorbing material based on fractal geometry, the wave-absorbing material is composed of a periodic arrangement of a three-dimensional unit cell structure in a plane, and the unit cell structure is a layered structure; the method comprises the following steps: determining impedance gradient correction coefficients of each layer of the unit cell structure according to layer structure parameters and a fractal dimension of the unit cell structure of the wave-absorbing material; determining equivalent electromagnetic parameters of each layer of the unit cell structure according to intrinsic electromagnetic parameters and layer structure parameters of each layer; determining complex propagation constants and intrinsic impedances of each layer of the unit cell structure by using the equivalent electromagnetic parameters and a working frequency; determining an input impedance of a surface layer of the unit cell structure by using the impedance gradient correction coefficients, the complex propagation constants, the intrinsic impedances and the layer structure parameters of each layer of the unit cell structure, and then determining surface reflectivity and reflection loss; determining whether the wave-absorbing material meets working frequency band index requirements, and if not, continuously optimizing the unit cell structure until the unit cell structure meets the working frequency band index requirements, and completing the design of the wave-absorbing material.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of fractal geometry and electromagnetic wave absorbing materials, and particularly relates to a design method of an absorbing material based on fractal geometry. BACKGROUND

[0002] Absorbing materials are widely used in many fields. With the increasing requirements for the electromagnetic wave absorption capacity of absorbing materials, current single geometric shape absorbing materials gradually fail to meet the requirements. For example, RFID technology realizes non-contact information transmission through electromagnetic waves. However, when the tag is attached to a metal surface, the strong reflection of the metal to the electromagnetic wave will cause serious signal attenuation between the tag and the card reader, resulting in card reading failure or shortening of the identification distance. Traditional solutions mostly increase the tag antenna power or add a non-conductive isolation layer, but the former increases energy consumption and cost, and the latter leads to an increase in the thickness of the tag and limited isolation efficiency. The existing design of absorbing materials lacks a systematic theoretical modeling method, and it is difficult to achieve precise impedance matching and wideband absorption for specific frequency bands (such as 13.56 MHz, 915 MHz, etc.) of RFID.

[0003] For another example, a microwave darkroom realizes efficient absorption of incident electromagnetic waves through the combination of absorbing materials and metal shielding bodies, providing a reflection-free electromagnetic environment for wireless communication product testing. Traditional absorbing materials mostly use ferrite plates or pyramidal structures, but their absorbing performance is limited by single geometric shape, and there are problems such as low low-frequency absorption efficiency, wideband matching difficulty, large thickness and weight, etc. For example, the reflection loss of traditional pyramidal absorbing materials is often greater than -10 dB below 1 GHz, which cannot meet the high-precision testing requirements. Although multi-layer gradient materials can expand the frequency band, they rely on the experience and trial-and-error method for design, and lack a systematic theoretical modeling method.

[0004] The fractal geometry theory has been proved in lossy dielectric type structures that multiple scattering and loss of electromagnetic waves can be enhanced through self-similar multi-scale configuration, and the complex magnetic permeability dispersion characteristics of magnetic materials can synergize with fractal structures to form a wideband absorbing system. Therefore, it is urgent to establish a design method of absorbing materials based on fractal geometry, which realizes the wideband and thin design of absorbing materials for RFID electronic tag anti-metal absorbing materials and microwave darkroom absorbing materials through parameterized modeling of fractal structure and theoretical calculation of electromagnetic performance. SUMMARY

[0005] In order to overcome the deficiencies in the prior art, the inventors have made intensive research and provided a design method of wave-absorbing material based on fractal geometry, which combines fractal geometry with wave-absorbing material, quantitatively describes the geometric complexity of the wave-absorbing material through the fractal dimension, combines the resonance effect factor and the equivalent electromagnetic parameters, and then derives an interface wave impedance model considering the structural resonance effect based on the equivalent transmission line theory, so as to realize accurate prediction of electromagnetic wave reflectivity and reflection loss, serve as an optimization index of the wave-absorbing material, and complete iterative optimization design of the wave-absorbing material.

[0006] The technical scheme provided by the present application is as follows:

[0007] In a first aspect, a design method of wave-absorbing material based on fractal geometry is provided, the wave-absorbing material is composed of periodic arrangement of a three-dimensional unit cell structure in a plane, and the unit cell structure is a layered structure; the design method comprises the following steps:

[0008] According to the application scenario of the wave-absorbing material, the thickness requirement of the wave-absorbing material and the index requirement under the working frequency band are determined, and an initial configuration of the unit cell structure of the wave-absorbing material is constructed;

[0009] The layer structure parameters and the fractal dimension of the unit cell structure of the wave-absorbing material are obtained, and the impedance gradient correction coefficient of each layer of the unit cell structure is determined by using the layer structure parameters and the fractal dimension of the unit cell structure;

[0010] The equivalent electromagnetic parameters of each layer of the unit cell structure are determined according to the intrinsic electromagnetic parameters and the layer structure parameters of each layer of the unit cell structure; and the complex propagation constant and the intrinsic impedance of each layer of the unit cell structure are determined by using the equivalent electromagnetic parameters and the working frequency;

[0011] The input impedance of the surface layer of the unit cell structure is determined by using the impedance gradient correction coefficient, the complex propagation constant, the intrinsic impedance and the layer structure parameters of each layer of the unit cell structure, and the surface reflectivity and the reflection loss are determined according to the input impedance of the surface layer;

[0012] Whether the wave-absorbing material meets the working frequency band index requirement is determined according to the surface reflectivity or the reflection loss of the unit cell structure, if not, the configuration and the layer structure parameters of the unit cell structure are continuously optimized until the unit cell structure meets the working frequency band index requirement, and the design of the wave-absorbing material is completed.

[0013] In a second aspect, a design device of wave-absorbing material based on fractal geometry is provided, comprising:

[0014] One or more processors;

[0015] A storage device for storing one or more programs,

[0016] When the one or more programs are executed by the one or more processors, the one or more processors implement the design method of wave-absorbing material based on fractal geometry of the first aspect.

[0017] In a third aspect, a readable storage medium has a computer program stored thereon, which, when executed by a processor, implements the method for designing a wave-absorbing material based on fractal geometry according to the first aspect.

[0018] In a fourth aspect, a computer program product comprises a computer program (also referred to as code or instructions) that, when executed, performs the method for designing a wave-absorbing material based on fractal geometry according to the first aspect.

[0019] The method for designing a wave-absorbing material based on fractal geometry according to the present application has the following beneficial effects:

[0020] The method for designing a wave-absorbing material based on fractal geometry according to the present application combines fractal geometry with wave-absorbing materials, quantitatively describes the geometric complexity of the wave-absorbing materials through a fractal dimension, combines a resonance effect factor and equivalent electromagnetic parameters, and derives an interface wave impedance model considering structural resonance effects based on an equivalent transmission line theory, to accurately predict electromagnetic wave reflectivity and reflection loss, as an optimization index for the wave-absorbing materials, to complete iterative optimization design of the wave-absorbing materials. BRIEF DESCRIPTION OF DRAWINGS

[0021] Figure 1 The flowchart of the method for designing a wave-absorbing material based on fractal geometry according to the present application. DETAILED DESCRIPTION

[0022] The features and advantages of the present application will become more apparent from the detailed description of the application.

[0023] The term "exemplary" is used herein to mean "serving as an example, instance, or illustration." Any implementation described herein as "exemplary" is not necessarily to be construed as preferred or advantageous over other implementations.

[0024] Reference Figure 1 The present application provides a method for designing a wave-absorbing material based on fractal geometry, the wave-absorbing material being composed of periodic arrangement of a three-dimensional unit cell structure in a plane, the unit cell structure being a layered structure; the method comprising the following steps:

[0025] Step 1: determining the thickness requirement of the wave-absorbing material and the reflection loss index under the working frequency band according to the application scenario of the wave-absorbing material, and constructing an initial configuration of the unit cell structure of the wave-absorbing material.

[0026] For example, when absorbing material is used as an anti-metal absorbing material for RFID electronic tags and is pasted on the back of the RFID electronic tag to absorb electromagnetic waves strongly reflected from the metal surface, for the 915MHz frequency band, the reflection loss of the absorbing material at this frequency point is required to be ≤-10dB and the thickness is ≤0.5mm.

[0027] When absorbing materials are used as broadband anti-interference absorbing materials for automotive electronics to eliminate electromagnetic interference, for the 77GHz millimeter-wave radar band, the absorbing layer is required to have a reflection loss ≤-15dB and a thickness ≤1.5mm in the 75GHz-79GHz frequency band.

[0028] When absorbing materials are used to construct microwave anechoic chambers, for X-band testing requirements, the absorbing layer must have a reflection loss of ≤-25dB and a thickness of ≤30mm in the 8-12GHz frequency band.

[0029] Step 2: Obtain the layer structure parameters of the unit cell structure of the absorbing material, and determine the fractal dimension of the unit cell structure using the box-counting dimension method; use the layer structure parameters and fractal dimension of the unit cell structure to determine the resonance effect factor and impedance gradient correction coefficient of each layer of the unit cell structure.

[0030] Unit cell configurations include honeycomb configuration, stepped cone configuration, woodpile configuration, square frame configuration, and composite configuration; honeycomb configuration is a multi-layered honeycomb gradient arrangement, stacked from largest to smallest; stepped cone configuration is a multi-layered cubic gradient arrangement, stacked from largest to smallest; woodpile configuration is a multi-layered staggered arrangement of cuboids; square frame configuration is a multi-layered cubic gradient arrangement, stacked from largest to smallest; composite configuration is a multi-layered arrangement of cuboids and squares.

[0031] The unit cell structure is a layered structure, and the layer structure parameters include the number of layers. l Duty cycle of each floor p and the thickness of each layer d Utilizing the number of layers l Duty cycle of each floor p and the thickness of each layer d The fractal dimension can uniquely determine a single-cell structure.

[0032] Resonance effect factors of each layer of the unit cell structure g ( k The formula for calculating ) is:

[0033] g ( k )= p ( k )·( D - D 1) D

[0034] p (k ) is the first k Layer duty cycle; D The fractal dimension of a unit cell structure; D 1 is the baseline fractal dimension, ranging from 2.5 to 3.

[0035] Impedance gradient correction factor G ( k The formula for calculating ) is:

[0036] G ( k )=1+ g ( k ) .

[0037] Step 3: Determine the equivalent electromagnetic parameters of each layer of the unit cell structure based on the intrinsic electromagnetic parameters and layer structure parameters of each layer; use the equivalent electromagnetic parameters and operating frequency to determine the complex propagation constant and intrinsic impedance of each layer of the unit cell structure.

[0038] The unit cell structure is a layered structure, and the materials used in different layers can be the same or different, and the corresponding intrinsic electromagnetic parameters can be the same or different.

[0039] Intrinsic electromagnetic parameters include the intrinsic permeability and intrinsic permittivity of the absorbing material.

[0040] Based on the intrinsic permeability and duty cycle of each layer in the unit cell structure, the equivalent permeability of each layer is determined using the following formula:

[0041]

[0042] in, μ eff ( k ) is the first k Layer equivalent permeability, p ( k ) is the first k Layer duty cycle, μ r ( k ) is the first k intrinsic permeability of the layer μ 0 represents the permeability of the air in the gap. μ 0 takes the value 1.

[0043] Based on the intrinsic dielectric constant and duty cycle of each layer in the unit cell structure, the equivalent dielectric constant of each layer is determined using the following formula:

[0044]

[0045] in, ε eff ( k ) is the first kEquivalent dielectric constant of the layer, p ( k ) is the first k Layer duty cycle, ε r ( k ) is the first k intrinsic dielectric constant of the layer, ε 0 represents the dielectric constant of the air gap. ε 0 takes the value 1.

[0046] Using equivalent electromagnetic parameters and operating frequency, the complex propagation constants of each layer of the unit cell structure are determined using the following formula:

[0047]

[0048] in, γ ( k ) is the first k Layered propagation constant, j It is a complex number. f For operating frequency, μ eff ( k ) is the first k Layer equivalent permeability, ε eff ( k ) is the first k Equivalent dielectric constant of the layer, c It is the speed of light.

[0049] The intrinsic impedance of each layer of the unit cell structure is determined using equivalent electromagnetic parameters, and the calculation formula is as follows:

[0050]

[0051] in, η 0( k ) is the first k Layer intrinsic impedance, μ eff ( k ) is the first k Layer equivalent permeability, ε eff ( k ) is the first k Equivalent dielectric constant of the layer.

[0052] Step 4: Using the impedance gradient correction coefficient, complex propagation constant, intrinsic impedance, and layer structure parameters of each layer of the unit cell structure, determine the input impedance of the surface layer of the unit cell structure, and determine the surface reflectivity and reflection loss based on the surface layer input impedance.

[0053] The input impedance of each layer in the unit cell structure is calculated using the following formula:

[0054]

[0055] in, η in ( k ) is the first k Layer input impedance, G ( k ) represents the impedance gradient correction factor; η 0( k ) is the first k Layer intrinsic impedance; γ ( k ) is the first k Layered propagation constant; d ( k ) is the first k Layer upon layer; η in ( k -1) is the first k -1 layer input impedance; η in (0) takes the value 1.

[0056] The formula for calculating the surface reflectance of a unit cell structure is as follows:

[0057]

[0058] in, r For surface reflectivity, η in ( l ) represents the surface layer input impedance.

[0059] Single-cell structure reflection loss R The calculation formula is as follows:

[0060]

[0061] Step 5: Determine whether the absorbing material meets the operating frequency band requirements based on the surface reflectivity or reflection loss of the unit cell structure. If not, continue to optimize the configuration and layer structure parameters of the unit cell structure until the unit cell structure meets the operating frequency band requirements, thus completing the design of the absorbing material.

[0062] When absorbing materials are used as anti-metal absorbing materials for RFID electronic tags, the fractal dimension is employed. D =2.5-3.0, duty cycle p =0.2-0.8 and layer thickness d The unit cell structure was optimized using parameter combinations of 0.3-0.5 mm to determine the surface reflectivity and reflection loss in the 915MHz and 13.56MHz frequency bands, in order to match the electromagnetic wave absorption requirements of the RFID operating frequency band.

[0063] When absorbing materials are used as broadband anti-interference absorbing materials for automotive electronics, fractal dimension is employed. D =2.5-3.0, duty cycle of each floor p =0.2-0.8 and layer thickness d The unit cell structure was optimized using parameter combinations ranging from 0.5 to 1.5 mm to determine the surface reflectivity and reflection loss in the 1 GHz to 80 GHz frequency band (covering 24 GHz and 77 GHz for automotive radar, and 5G / 6G and 3 GHz to 60 GHz for vehicle networking communication) in order to match the electromagnetic wave absorption requirements of the automotive electronic operating frequency band.

[0064] When using microwave absorbing materials to construct microwave anechoic chambers, fractal dimension is employed. D =2.5-3.0, duty cycle of each floor p =0.2-0.8 and layer thickness d The unit cell structure was optimized using parameter combinations ranging from 10 to 30 mm to determine the surface reflectivity and reflection loss in the 1 GHz to 40 GHz frequency band, in order to match the broadband absorption requirements of the microwave anechoic chamber operating frequency band.

[0065] When absorbing materials are used as high-frequency anti-interference absorbing materials for 5G base stations, fractal dimension is employed. D =2.5-3.0, duty cycle of each floor p =0.2-0.8 and layer thickness d The unit cell structure was optimized by combining parameters of 1-5mm to determine the surface reflectivity and reflection loss in the 24GHz-40GHz frequency band, in order to match the electromagnetic wave absorption requirements of the 5G operating frequency band.

[0066] When absorbing materials are used as high-frequency anti-interference absorbing materials for computers, fractal dimension is employed. D =2.5-3.0, duty cycle of each floor p =0.2-0.8 and layer thickness d The unit cell structure was optimized by combining parameters from 1 to 10 mm to determine the surface reflectivity and reflection loss in the 1 GHz to 20 GHz frequency band, in order to match the electromagnetic wave absorption requirements of the computer's operating frequency band.

[0067] When absorbing materials are used as diamagnetic broadband absorbing materials in nuclear magnetic resonance (NMR) equipment, fractal dimension is employed. D =2.5-3.0, duty cycle of each floor p =0.2-0.8 and layer thickness d The unit cell structure was optimized by combining parameters of 5-10 mm to determine the surface reflectivity and reflection loss in the 10MHz-1GHz frequency band, in order to match the electromagnetic wave absorption requirements of the nuclear magnetic resonance equipment.

[0068] When absorbing materials are used as broadband weather-resistant and anti-interference absorbing materials for ground command posts, fractal dimension is employed. D=2.5-3.0, duty cycle of each floor p =0.2-0.8 and layer thickness d The unit cell structure was optimized by combining parameters of 2-5mm to determine the surface reflectivity and reflection loss in the 100MHz-20GHz frequency band, in order to match the electromagnetic wave absorption requirements of the ground command post's operating frequency band.

[0069] When using microwave absorbing materials as broadband anti-interference absorbing materials inside the towers of offshore wind turbines, fractal dimension is employed. D =2.5-3.0, duty cycle of each floor p =0.2-0.8 and layer thickness d The unit cell structure was optimized by combining parameters of 2-5mm to determine the surface reflectivity and reflection loss in the 100MHz-10GHz frequency band, in order to match the electromagnetic wave absorption requirements of offshore wind power equipment.

[0070] When using microwave absorbing materials as broadband, temperature-resistant, and interference-resistant microwave absorbing materials in the confined space of tank equipment, fractal dimension is employed. D =2.5-3.0, duty cycle of each floor p =0.2-0.8 and layer thickness d The unit cell structure was optimized by combining parameters of 2-5mm to determine the surface reflectivity and reflection loss in the 1GHz-40GHz frequency band, in order to match the electromagnetic wave absorption requirements of the tank's operating frequency band.

[0071] When absorbing materials are used as broadband anti-interference absorbing materials within the metal cavities of marine vessels, fractal dimension is employed. D =2.5-3.0, duty cycle of each floor p =0.2-0.8 and layer thickness d The unit cell structure was optimized by combining parameters of 1-3 mm to determine the surface reflectivity and reflection loss in the 10MHz-40GHz frequency band, in order to match the electromagnetic wave absorption requirements of ship communication frequency bands.

[0072] When using radar-absorbing materials as broadband lightweight radar-stealing radar-absorbing materials for civilian drones, fractal dimension is employed. D =2.5-3.0, duty cycle of each floor p =0.2-0.8 and layer thickness d The unit cell structure was optimized using parameter combinations ranging from 0.5 to 2 mm to determine the surface reflectivity and reflection loss in the 2 GHz to 18 GHz frequency band, in order to match the electromagnetic wave absorption requirements of the radar operating frequency band.

[0073] When absorbing materials are used as high-frequency anti-interference absorbing materials for smartphones, fractal dimension is employed. D =2.5-3.0, duty cycle of each floor p =0.2-0.8 and layer thickness dThe unit cell structure was optimized using parameter combinations ranging from 0.5 to 1.5 mm to determine the surface reflectivity and reflection loss in the 3 GHz to 60 GHz frequency band, in order to match the electromagnetic wave absorption requirements of smartphone operating frequency bands.

[0074] When absorbing materials are used as broadband weather-resistant and anti-interference absorbing materials for satellite antennas, fractal dimension is employed. D =2.5-3.0, duty cycle of each floor p =0.2-0.8 and layer thickness d The unit cell structure was optimized by combining parameters of 1-3 mm to determine the surface reflectivity and reflection loss in the 4GHz-40GHz frequency band, in order to match the electromagnetic wave absorption requirements of the satellite communication frequency band.

[0075] The following example illustrates the design process of broadband multimodal vibration suppression damping materials based on fractal geometry.

[0076] Taking the design of microwave absorbing materials for X-band (8-12GHz) microwave anechoic chambers as an example, the specific implementation process is explained as follows:

[0077] 1. Determine the operating frequency band and performance requirements: For X-band testing requirements, the absorbing material is required to have a reflection loss of ≤-10dB in the 8-12GHz frequency band, a thickness of ≤30mm, and be compatible with the reflection boundary conditions of the metal shield.

[0078] 2. Unit cell structure geometric modeling: A five-layer honeycomb fractal structure was adopted. The box-counting method was used, and cubic meshes with side lengths of 0.5mm, 0.1mm, and 0.02mm were used to cover the three-dimensional space of the structure. After counting the number of meshes, regression analysis was performed on lnNr and ln(1 / r) to obtain the target fractal dimension. D =2.87.

[0079] Unit cell duty cycle p (1) = 87.72, p (2) = 49.4, p (3) = 26.78, p (4) = 26.78, p (5) = 21.76; d (1) = 2.4 mm, d (2) = 0.9 mm, d (3) = 3mm, d (4) = 3.6 mm, d (5) = 0.4 mm.

[0080] 3. Selection of magnetic material parameters: Graphene composite material was selected, with an equivalent magnetic permeability of... μ eff =1 -j 0 (10GHz), equivalent dielectric constantε eff =11.9- j 5.0 (10GHz).

[0081] 4. Interface wave impedance calculation: η in (1) = 1.25, η in (2) = 0.66, η in (3) = 0.34, η in (4) = 0.71, η in (5) = 0.78.

[0082] 5. Calculation of reflection loss: R =-18.3dB. Calculations for reflection loss in the 8-12GHz range show that the results meet the performance requirements for microwave anechoic chamber absorbing materials in the operating frequency band.

[0083] Fractal dimension was determined through simulation using HFSS software. D When the value is 2.87, the reflection loss in the 8-12GHz band is ≤-10dB, which is consistent with the theoretical calculation. When a microwave anechoic chamber is built by combining the absorbing material with the metal shield, the sidelobe level is reduced from -12dB to -28dB when testing the antenna pattern of a certain X-band. The sidelobe level is reduced from -12dB to -28dB, a reduction of 16dB. The main lobe gain test error is reduced from ±1.5dB to ±0.3dB, which verifies the effect of the solution on improving the test accuracy.

[0084] The present invention also provides a design device for wave-absorbing materials based on fractal geometry, comprising:

[0085] One or more processors;

[0086] Storage device for storing one or more programs.

[0087] When the one or more programs are executed by the one or more processors, the one or more processors implement the design method for wave-absorbing materials based on fractal geometry as described in the first aspect.

[0088] The present invention also provides a readable storage medium having a computer program stored thereon, which, when executed by a processor, implements the design method of the wave-absorbing material based on fractal geometry described in the first aspect.

[0089] The readable storage media include, but are not limited to, USB flash drives, portable hard drives, read-only memory (ROM), random access memory (RAM), magnetic disks, optical disks, and other media capable of storing program code.

[0090] This invention also provides a computer program product, comprising: a computer program (also referred to as code or instructions), which, when run, executes the design method for damping materials based on fractal geometry described in the first aspect. In the computer program product, various typical unit cell structures can be pre-stored; by selecting a pre-stored unit cell structure, the initial geometric configuration of the damping material can be quickly constructed.

[0091] In the above embodiments, implementation can be achieved, in whole or in part, through software, hardware, firmware, or any combination thereof. When implemented using software, it can be implemented, in whole or in part, as a computer program product. The computer program product includes one or more computer instructions. When the computer instructions are loaded and executed on a computer, all or part of the processes or functions described in the embodiments of this application are generated. The computer can be a general-purpose computer, a special-purpose computer, a computer network, or other programmable device. The computer instructions can be stored in a computer-readable storage medium or transmitted from one computer-readable storage medium to another. For example, the computer instructions can be transmitted from one website, computer, server, or data center to another via wired (e.g., coaxial cable, fiber optic, digital subscriber line (DSL)) or wireless (e.g., infrared, microwave, etc.) means.

[0092] Those skilled in the art will recognize that the units and algorithm steps of the various examples described in conjunction with the embodiments disclosed herein can be implemented in electronic hardware, or a combination of computer software and electronic hardware. Whether these functions are implemented in hardware or software depends on the specific application and design constraints of the technical solution. Those skilled in the art can use different methods to implement the described functions for each specific application, but such implementation should not be considered beyond the scope of this application.

[0093] Those skilled in the art will clearly understand that, for the sake of convenience and brevity, the specific working processes of the devices, apparatuses, and modules described above can be referred to the corresponding processes in the foregoing method embodiments, and will not be repeated here.

[0094] The present invention has been described in detail above with reference to specific embodiments and exemplary examples; however, these descriptions should not be construed as limiting the present invention. Those skilled in the art will understand that various equivalent substitutions, modifications, or improvements can be made to the technical solutions and embodiments of the present invention without departing from the spirit and scope of the invention, and all such modifications and improvements fall within the scope of the present invention. The scope of protection of the present invention is defined by the appended claims.

[0095] The contents not described in detail in this specification are common knowledge to those skilled in the art.

Claims

1. A design method for wave-absorbing materials based on fractal geometry, characterized in that, The absorbing material is composed of a periodic arrangement of three-dimensional unit cell structures in a plane, and the unit cell structure is a layered structure; the design method includes: Based on the application scenario of the absorbing material, the thickness requirements and index requirements of the absorbing material under the working frequency band are determined, and the initial configuration of the unit cell structure of the absorbing material is constructed. Obtain the layer structure parameters and fractal dimension of the unit cell structure of the absorbing material, and use the layer structure parameters and fractal dimension of the unit cell structure to determine the impedance gradient correction coefficient of each layer of the unit cell structure. Based on the intrinsic electromagnetic parameters and layer structure parameters of each layer of the unit cell structure, the equivalent electromagnetic parameters of each layer of the unit cell structure are determined; using the equivalent electromagnetic parameters and the operating frequency, the complex propagation constant and intrinsic impedance of each layer of the unit cell structure are determined. Using the impedance gradient correction coefficient, complex propagation constant, intrinsic impedance, and layer structure parameters of each layer of the unit cell structure, the input impedance of the surface layer of the unit cell structure is determined, and the surface reflectivity and reflection loss are determined based on the surface layer input impedance. The surface reflectivity or reflection loss of the unit cell structure is used to determine whether the absorbing material meets the requirements of the working frequency band. If it does not meet the requirements, the configuration and layer structure parameters of the unit cell structure are optimized until the unit cell structure meets the requirements of the working frequency band, and the design of the absorbing material is completed. The impedance gradient correction coefficient of each layer of the unit cell structure G ( k )for: G ( k )=1+ g ( k ) g ( k )= p ( k )·( D - D 1) D in, G ( k ) is the first k Layer impedance gradient correction factor; g ( k ) is the first k Layer resonance effect factor; p ( k ) is the first k Layer duty cycle; D The fractal dimension of a unit cell structure; D 1 is the baseline fractal dimension, ranging from 2.5 to 3.

2. The design method for wave-absorbing materials based on fractal geometry according to claim 1, characterized in that, The intrinsic electromagnetic parameters of each layer of the unit cell structure include intrinsic permeability and intrinsic permittivity. The equivalent permeability of each layer is determined based on the intrinsic permeability and duty cycle of each layer in the unit cell structure, using the following formula: in, μ eff ( k ) is the first k Layer equivalent permeability, p ( k ) is the first k Layer duty cycle, μ r ( k ) is the first k intrinsic permeability of the layer μ 0 represents the permeability at the void. μ 0 takes the value 1; The equivalent dielectric constant of each layer is determined based on its intrinsic dielectric constant and duty cycle, using the following formula: in, ε eff ( k ) is the first k Equivalent dielectric constant of the layer, p ( k ) is the first k Layer duty cycle, ε r ( k ) is the first k intrinsic dielectric constant of the layer, ε 0 represents the dielectric constant at the gap. ε 0 takes the value 1.

3. The design method for wave-absorbing materials based on fractal geometry according to claim 2, characterized in that, The complex propagation constant γ ( k It is determined by the following formula: in, γ ( k ) is the first k Layered propagation constant, j It is a complex number. f For operating frequency, μ eff ( k ) is the first k Layer equivalent permeability, ε eff ( k ) is the first k Equivalent dielectric constant of the layer, c It is the speed of light.

4. The design method for wave-absorbing materials based on fractal geometry according to claim 2, characterized in that, The intrinsic impedance η 0( k It is determined by the following formula: in, η 0( k ) is the first k Layer intrinsic impedance, μ eff ( k ) is the first k Layer equivalent permeability, ε eff ( k ) is the first k Equivalent dielectric constant of the layer.

5. The design method for wave-absorbing materials based on fractal geometry according to claim 1, characterized in that, The input impedance of each layer of the unit cell structure is determined by the following formula: in, η in ( k ) is the first k Layer input impedance; G ( k ) represents the impedance gradient correction factor; η 0( k ) is the first k Layer intrinsic impedance; γ ( k ) is the first k Layered propagation constant; d ( k ) is the first k Layer upon layer, thick; η in ( k -1) is the first k -1 layer input impedance; η in (0) takes the value 1.

6. The design method for wave-absorbing materials based on fractal geometry according to claim 1, characterized in that, The surface reflectivity of the unit cell structure r Determined by the following formula: The single-cell structure reflection loss R Determined by the following formula: in, r For surface reflectivity, R For reflection loss, η in ( l ) represents the surface layer input impedance.

7. The design method for wave-absorbing materials based on fractal geometry according to claim 1, characterized in that, When optimizing the configuration and layer structure parameters of a unit cell structure, the selection criteria for the fractal dimension and layer structure parameters of the unit cell structure are as follows: When absorbing materials are used as anti-metal absorbing materials for RFID electronic tags, the fractal dimension is employed. D =2.5-3.0, duty cycle of each floor p =0.2-0.8 and layer thickness d The unit cell structure was optimized using parameter combinations of 0.3-0.5mm to determine the surface reflectivity and reflection loss in the 915MHz and 13.56MHz frequency bands, in order to match the electromagnetic wave absorption requirements of the RFID operating frequency band. When absorbing materials are used as broadband anti-interference absorbing materials for automotive electronics, fractal dimension is employed. D =2.5-3.0, duty cycle of each floor p =0.2-0.8 and layer thickness d The unit cell structure was optimized using parameter combinations of 0.5-1.5mm to determine the surface reflectivity and reflection loss in the 1GHz-80GHz frequency band, in order to match the electromagnetic wave absorption requirements of automotive electronic operating frequency bands. When using microwave absorbing materials to construct microwave anechoic chambers, fractal dimension is employed. D =2.5-3.0, duty cycle of each floor p =0.2-0.8 and layer thickness d =10-30mm parameter combination to optimize unit cell structure, determine surface reflectivity and reflection loss in 1GHz-40GHz frequency band, in order to match the broadband absorption requirements of microwave anechoic chamber operating frequency band; When absorbing materials are used as high-frequency anti-interference absorbing materials for 5G base stations, fractal dimension is employed. D =2.5-3.0, duty cycle of each floor p =0.2-0.8 and layer thickness d =1-5mm parameter combination to optimize unit cell structure, determine surface reflectivity and reflection loss in 24GHz-40GHz frequency band to match electromagnetic wave absorption requirements of 5G operating frequency band; When absorbing materials are used as high-frequency anti-interference absorbing materials for computers, fractal dimension is employed. D =2.5-3.0, duty cycle of each floor p =0.2-0.8 and layer thickness d =1-10mm parameter combination to optimize unit cell structure, determine surface reflectivity and reflection loss in 1GHz-20GHz frequency band, so as to match the electromagnetic wave absorption requirements of computer operating frequency band; When absorbing materials are used as diamagnetic broadband absorbing materials in nuclear magnetic resonance (NMR) equipment, fractal dimension is employed. D =2.5-3.0, duty cycle of each floor p =0.2-0.8 and layer thickness d The parameter combination of 5-10mm was optimized to improve the unit cell structure and determine the surface reflectivity and reflection loss in the 10MHz-1GHz frequency band to match the electromagnetic wave absorption requirements of the nuclear magnetic resonance equipment. When absorbing materials are used as broadband weather-resistant and anti-interference absorbing materials for ground command posts, fractal dimension is employed. D =2.5-3.0, duty cycle of each floor p =0.2-0.8 and layer thickness d =2-5mm parameter combination optimization unit cell structure, determine surface reflectivity and reflection loss in 100MHz-20GHz frequency band, so as to match the electromagnetic wave absorption requirements of the ground command post operating frequency band. When using microwave absorbing materials as broadband anti-interference absorbing materials inside the towers of offshore wind turbines, fractal dimension is employed. D =2.5-3.0, duty cycle of each floor p =0.2-0.8 and layer thickness d =2-5mm parameter combination optimization unit cell structure, determine surface reflectivity and reflection loss in 100MHz-10GHz frequency band, in order to match the electromagnetic wave absorption requirements of offshore wind power equipment; When using microwave absorbing materials as broadband, temperature-resistant, and interference-resistant microwave absorbing materials in the confined space of tank equipment, fractal dimension is employed. D =2.5-3.0, duty cycle of each floor p =0.2-0.8 and layer thickness d =2-5mm parameter combination optimization unit cell structure, determine surface reflectivity and reflection loss in the 1GHz-40GHz frequency band, in order to match the electromagnetic wave absorption requirements of the tank's operating frequency band; When absorbing materials are used as broadband anti-interference absorbing materials within the metal cavities of marine vessels, fractal dimension is employed. D =2.5-3.0, duty cycle of each floor p =0.2-0.8 and layer thickness d =1-3mm parameter combination to optimize unit cell structure, determine surface reflectivity and reflection loss in 10MHz-40GHz frequency band to match electromagnetic wave absorption requirements of ship communication frequency band; When using radar-absorbing materials as broadband lightweight radar-stealing radar-absorbing materials for civilian drones, fractal dimension is employed. D =2.5-3.0, duty cycle of each floor p =0.2-0.8 and layer thickness d The unit cell structure was optimized using parameter combinations ranging from 0.5 to 2 mm to determine the surface reflectivity and reflection loss in the 2 GHz to 18 GHz frequency band, in order to match the electromagnetic wave absorption requirements of the radar operating frequency band. When absorbing materials are used as high-frequency anti-interference absorbing materials for smartphones, fractal dimension is employed. D =2.5-3.0, duty cycle of each floor p =0.2-0.8 and layer thickness d The unit cell structure was optimized using parameter combinations of 0.5-1.5mm to determine the surface reflectivity and reflection loss in the 3GHz-60GHz frequency band, in order to match the electromagnetic wave absorption requirements of smartphone operating frequency bands. When absorbing materials are used as broadband weather-resistant and anti-interference absorbing materials for satellite antennas, fractal dimension is employed. D =2.5-3.0, duty cycle of each floor p =0.2-0.8 and layer thickness d The unit cell structure was optimized by combining parameters of 1-3 mm to determine the surface reflectivity and reflection loss in the 4GHz-40GHz frequency band, in order to match the electromagnetic wave absorption requirements of the satellite communication frequency band.

8. A design device for wave-absorbing materials based on fractal geometry, characterized in that, include: One or more processors; Storage device for storing one or more programs. When the one or more programs are executed by the one or more processors, the one or more processors implement the design method of the wave-absorbing material based on fractal geometry as described in any one of claims 1 to 7.

9. A computer program product, characterized in that, The computer program product includes: a computer program that, when run, executes the design method for wave-absorbing materials based on fractal geometry as described in any one of claims 1 to 7.

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