Optimization method of broadband multilayer wave-absorbing material
By applying the Levenberg-Marquardt algorithm to optimize the thickness of each layer of the multi-layer absorbing material, the problem of complex design process and slow speed in the existing technology is solved, and the rapid optimization design of wide-band multi-layer absorbing material is achieved to achieve good absorption Wave performance.
Patent Information
- Application Number
- CN202411467709.2
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2024-10-21
- Publication Date
- 2025-02-11
AI Technical Summary
When designing multi-layer absorbing materials, the use of global optimization algorithms in the prior art leads to complex design process, slow speed, low search efficiency, long design time, and difficult to achieve rapid optimization of broadband multi-layer absorbing materials.
The Levenberg–Marquardt(LM) algorithm is used to optimize the thickness of each layer of the broadband multi-layer absorbing material. By setting the objective function, calculating the residual and Jacobian matrix, and iteratively updating the parameters until the optimal thickness value is reached.
The rapid optimization design of wide-band multi-layer electromagnetic wave absorbing material is realized, so that the reflection loss of the designed multi-layer film in the broadband frequency range reaches the target value, and the design efficiency and accuracy are improved.
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Abstract
Description
Technical Field
[0001] The present application relates to the field of absorbing material design, and in particular to an optimization method for a broadband multilayer absorbing material. Background Art
[0002] The rapid development of radar detection technology has expanded the electromagnetic wave frequency band used by radar from the X band to multiple bands such as L, S, C, X, and Ku. This expansion poses an increasingly serious threat to one's own military targets. At present, since traditional absorbing materials often only show excellent absorption performance in a narrow frequency band, it is difficult to meet the requirements of modern military and communication technology for broadband and thin absorbing materials. In addition, with the widespread application of communication technology, the use of spectrum resources is increasingly inclined to the microwave band, which may have adverse effects on human health. Therefore, the development of new absorbing materials that can achieve broadband absorption has become a key technical problem that needs to be solved in the field of electromagnetic wave absorbing technology.
[0003] In order to increase the frequency band width covered by the absorbing material, the traditional strategy is usually to improve the magnetic permeability of the absorbing material in each frequency band to enhance its absorption efficiency of electromagnetic waves. However, the latest research shows that it is difficult to obtain the ideal broadband absorbing effect by simply improving the absorbing properties of the material itself. Although magnetic materials, such as carbonyl iron, iron silicon aluminum, etc., are considered suitable for designing broadband absorbing materials, after selecting a certain proportion of a certain material, its resonant absorption frequency is often limited to a specific frequency band of 2 to 18 GHz, and it is difficult to achieve full-band broadband absorption. Therefore, designing multilayer absorbing materials based on a variety of different materials has become an important research direction to solve this problem.
[0004] Directly analyzing the absorbing characteristics of different combinations of multilayer absorbing materials through experiments is not only time-consuming and labor-intensive, but may also lead to a large amount of waste of experimental materials. In the design of absorbing materials, global optimization algorithms are usually used to design the parameters of each layer of absorbing materials (such as the thickness of absorbing films), such as genetic algorithms, simulated annealing algorithms, particle swarm optimization, differential evolution, and ant colony algorithms. However, the design of multilayer absorbing materials based on global optimization algorithms usually requires processing multiple individuals in the group rather than a single solution, making the design process relatively complex and slow, resulting in problems such as low search efficiency and long design time.
[0005] To address the above-mentioned problems, no effective solution has been proposed yet. Summary of the invention
[0006] The embodiment of the present application provides an optimization method for broadband multilayer absorbing materials, so as to at least solve the technical problem that the related art adopts a global optimization algorithm to design multilayer absorbing materials, which makes the design process relatively complex and slow, resulting in low search efficiency and long design time.
[0007] According to one aspect of an embodiment of the present application, a method for optimizing a broadband multilayer absorbing material is provided, comprising: optimizing the thickness of each layer of the broadband multilayer absorbing material using a Levenberg–Marquardt (LM) algorithm to obtain an optimal thickness value of the broadband multilayer absorbing material; wherein the steps of the optimization process are: S1: setting an objective function F, an initial parameter value X0, and a maximum number of iterations; wherein the initial parameter value is an initial thickness value; S2: calculating a residual r(X) and a Jacobian matrix J(X) under the current parameters; S3: using an iterative formula d K+1 =d K -(J T J+λI) -1 J T r calculates the update direction; where I is the unit matrix and λ is the damping factor; S4: Update parameter X new =X old +d; S5: Calculate the new residual r(X new ), and optimize the objective function F so that the objective function F is minimized; S6: determine whether the number of iterations reaches the maximum number of iterations or whether the accuracy of the optimization result reaches the set accuracy; if so, output the optimal parameter; wherein the optimal parameter is the optimal thickness value; if not, execute S7; S7: determine r(X new ) is less than r(X old ); if so, accept the update X new , reduce the damping factor λ and execute S2; if not, increase the damping factor λ and keep X old , and execute S3.
[0008] Optionally, the objective function F is expressed as: Among them, RL is the reflection loss within the target frequency band; R0 is the target reflection loss; r is the residual.
[0009] Optionally, when the structure of the broadband multi-layer absorbing material is a three-layer structure, the target frequency band of the three-layer structure is 4 to 8 GHz, and the target reflection loss is -5 dB.
[0010] Optionally, when the structure of the broadband multilayer absorbing material is a four-layer structure, the target frequency band of the four-layer structure is 8 to 18 GHz, and the target reflection loss is -10 dB.
[0011] Optionally, when the structure of the broadband multi-layer absorbing material is a five-layer structure, the target frequency band of the five-layer structure is 2 to 18 GHz, and the target reflection loss is -12 dB.
[0012] Optionally, when the structure of the broadband multilayer absorbing material is a three-layer structure, the optimized thickness range of the three-layer structure is 0 to 4 mm; when the structure of the broadband multilayer absorbing material is a four-layer structure or a five-layer structure, the optimized thickness range of the four-layer structure or the five-layer structure is both 0 to 5 mm.
[0013] Optionally, the thickness of the three-layer structure is 3.40mm, 3.15mm and 0.90mm respectively. Within the target frequency band, the average reflection loss is -4.95dB, and the minimum value reaches -5.40dB; the thickness of the four-layer structure is 3.29mm, 1.36mm, 1.72mm and 4.46mm respectively. Within the target frequency band, the average reflection loss is -9.91dB, and the minimum value reaches -10.82dB; the thickness of the five-layer structure is 3.67mm, 3.50mm, 2.34mm, 1.26mm and 4.88mm respectively. Within the target frequency band, the average reflection loss is -11.03dB, and the minimum value reaches -25.84dB.
[0014] Optionally, the method further comprises: collecting electromagnetic parameters of different types of absorbing materials, numbering the different types of absorbing materials respectively, and establishing an absorbing material database; wherein the electromagnetic parameters comprise at least one of the following: relative dielectric constant, relative magnetic permeability.
[0015] In the embodiment of the present application, the local optimization algorithm Levenberg-Marquardt algorithm is applied to the design of the multilayer absorbing material. Combined with the proposed objective function, the rapid optimization design of the broadband multilayer electromagnetic wave absorbing material is realized, so that the reflection loss of the designed multilayer film in the broadband frequency range reaches the target value, thereby solving the technical problem that the design process of the multilayer absorbing material based on the global optimization algorithm in the related art is relatively complicated and slow, resulting in low search efficiency and long design time, and the technical effect of quickly realizing the optimization of the thickness of the broadband multilayer absorbing material and achieving good absorbing performance under thin thickness is achieved. BRIEF DESCRIPTION OF THE DRAWINGS
[0016] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the following briefly introduces the drawings required for use in the embodiments or the prior art descriptions. Obviously, the drawings described below are only some embodiments of the present application, and for ordinary technicians in this field, other embodiments can be obtained based on these drawings without creative work.
[0017] Figure 1 A flowchart of the Levenberg–Marquardt algorithm provided in an embodiment of the present application;
[0018] Figure 2 A schematic diagram of the structure of a multi-layer absorbing material designed for an embodiment of the present application;
[0019] Figure 3 A schematic diagram of the wave absorbing effect of the three-layer wave absorbing material provided in the embodiment of the present application;
[0020] Figure 4 A schematic diagram of the wave absorbing effect of the four-layer wave absorbing material provided in the embodiment of the present application;
[0021] Figure 5 Schematic diagram of the wave absorbing effect of the five-layer wave absorbing material provided in the embodiment of the present application. DETAILED DESCRIPTION
[0022] The embodiments of the present application will be described in more detail below with reference to the accompanying drawings. Although certain embodiments of the present application are shown in the accompanying drawings, it should be understood that the embodiments of the present application can be implemented in various forms and should not be interpreted as being limited to the embodiments described herein. Instead, these embodiments are provided to provide a more thorough and complete understanding of the embodiments of the present application. It should be understood that the drawings and embodiments of the present application are only for exemplary purposes and are not intended to limit the scope of protection of the present application.
[0023] According to one aspect of the embodiment of the present application, a method for optimizing a broadband multilayer absorbing material is provided, comprising: optimizing the thickness of each layer of the broadband multilayer absorbing material using the Levenberg-Marquardt algorithm to obtain an optimal thickness value of the broadband multilayer absorbing material. That is, the Levenberg-Marquardt algorithm is applied to the performance optimization of multiple absorbing materials, and the thickness of each layer of different multilayer absorbing materials is optimized using the Levenberg-Marquardt algorithm to find the optimal thickness value of the multilayer absorbing material, thereby achieving the purpose of designing the broadband multilayer absorbing material.
[0024] It should be noted that the Levenberg-Marquardt algorithm is one of the most commonly used nonlinear least squares algorithms, which is between the Newton method and the gradient descent method. It uses the gradient derivative method to find the maximum or minimum value of the objective function. It has the advantages of high stability, short iteration step, low computational complexity, high efficiency, and high precision.
[0025] Figure 1 The flowchart of the Levenberg–Marquardt algorithm provided in the embodiment of the present application is as follows: Figure 1 As shown, the Levenberg–Marquardt algorithm includes the following optimization steps:
[0026] S1: Set the objective function F, the initial value of the parameter X0 and the maximum number of iterations; the initial value of the parameter is the initial value of the thickness;
[0027] S2: Calculate the residual r(X) and Jacobian matrix J(X) under the current parameters;
[0028] S3: Using the iterative formula d K+1 =d K -(J T J+λI) -1 J T r calculates the update direction; where I is the unit matrix and λ is the damping factor;
[0029] S4: Update parameter X new =X old +d; S5: Calculate the new residual r(X new ), and optimize the objective function F so that the objective function F is minimized;
[0030] S6: Determine whether the number of iterations reaches the maximum number of iterations or whether the accuracy of the optimization result reaches the set accuracy; if so, output the optimal parameter; wherein the optimal parameter is the optimal thickness value; if not, execute S7;
[0031] S7: Determine r(X new ) is less than r(X old ); if so, accept the update X new , reduce the damping factor λ and execute S2; if not, increase the damping factor λ and keep X old , and execute S3.
[0032] Among them, broadband multilayer absorbing materials have good loss characteristics in the radar band.
[0033] In the embodiment of the present application, the local optimization algorithm Levenberg-Marquardt algorithm is applied to the design of the multilayer absorbing material. Combined with the proposed objective function, the rapid optimization design of the broadband multilayer electromagnetic wave absorbing material is realized, so that the reflection loss of the designed multilayer film in the broadband frequency range reaches the target value, thereby solving the technical problem that the design process of the multilayer absorbing material based on the global optimization algorithm in the related art is relatively complicated and slow, resulting in low search efficiency and long design time, and the technical effect of quickly realizing the optimization of the thickness of the broadband multilayer absorbing material and achieving good absorbing performance under thin thickness is achieved.
[0034] Compared with the prior art, the embodiment of the present application applies the Levenberg-Marquardt algorithm to the design optimization of broadband multilayer absorbing materials, improves the stability during iteration, and due to the use of second-order derivatives, its convergence speed is greatly improved compared with other algorithms. On a computer with a CPU main frequency of 2.40GHz, the speed of designing a multilayer absorbing material with no more than 5 layers using a single-core CPU is 1 to 4 seconds, realizing the rapid design of multilayer absorbing materials. Under high-precision sampling conditions, the Levenberg-Marquardt algorithm avoids the problem of significant decrease in optimization efficiency with the increase of sampling points caused by the optimization of the group by the global optimization algorithm because it only optimizes individuals, and can meet the requirements of high-precision design.
[0035] As an optional embodiment, the expression of the objective function F is: Among them, RL is the reflection loss within the target frequency band; R0 is the target reflection loss; r is the residual.
[0036] As an optional embodiment, when the structure of the broadband multilayer absorbing material is a three-layer structure, the target frequency band of the three-layer structure is 4 to 8 GHz, and the target reflection loss is -5 dB. When the structure of the broadband multilayer absorbing material is a four-layer structure, the target frequency band of the four-layer structure is 8 to 18 GHz, and the target reflection loss is -10 dB. When the structure of the broadband multilayer absorbing material is a five-layer structure, the target frequency band of the five-layer structure is 2 to 18 GHz, and the target reflection loss is -12 dB.
[0037] Optionally, the broadband multilayer absorbing material has three-layer, four-layer and five-layer structures respectively; the target frequency band of the three-layer structure is 4 to 8 GHz, and the target reflection loss is -5dB; the target frequency band of the four-layer structure is 8 to 18 GHz, and the target reflection loss is -10dB; the target frequency band of the five-layer structure is 2 to 18 GHz, and the target reflection loss is -12dB.
[0038] As an optional embodiment, when the structure of the broadband multilayer absorbing material is a three-layer structure, the optimized thickness range of the three-layer structure is 0 to 4 mm; when the structure of the broadband multilayer absorbing material is a four-layer structure or a five-layer structure, the optimized thickness range of the four-layer structure or the five-layer structure is both 0 to 5 mm.
[0039] Optionally, the broadband multilayer absorbing material has three-layer, four-layer and five-layer structures respectively; the optimized thickness range of the three-layer structure is 0-4 mm, and the optimized thickness ranges of the four-layer structure and the five-layer structure are both 0-5 mm.
[0040] As an optional embodiment, the thickness of the three-layer structure is 3.40mm, 3.15mm and 0.90mm respectively. Within the target frequency band, the average reflection loss is -4.95dB, and the minimum value reaches -5.40dB; the thickness of the four-layer structure is 3.29mm, 1.36mm, 1.72mm and 4.46mm respectively. Within the target frequency band, the average reflection loss is -9.91dB, and the minimum value reaches -10.82dB; the thickness of the five-layer structure is 3.67mm, 3.50mm, 2.34mm, 1.26mm and 4.88mm respectively. Within the target frequency band, the average reflection loss is -11.03dB, and the minimum value reaches -25.84dB.
[0041] Optionally, the broadband multilayer absorbing material has three, four and five layers of structures respectively; the three-layer absorbing material structure has thicknesses of d1=3.40mm, d2=3.15mm and d3=0.90mm respectively, and within the target frequency band, the average reflection loss is -4.95dB, and the minimum value can reach -5.40dB; the four-layer absorbing material structure has thicknesses of d1=3.29mm, d2=1.36mm, d3=1.72mm and d4=4.46mm. Within the target frequency band, the average reflection loss is -9.91dB, and the minimum value can reach -10.82dB. The five-layer absorbing material structure has thicknesses of d1=3.67mm, d2=3.50mm, d3=2.34mm, d4=1.26mm and d5=4.88mm. Within the target frequency band, the average reflection loss is -11.03dB, and the minimum value can reach -25.84dB.
[0042] As an optional embodiment, the method further includes: collecting electromagnetic parameters of different types of absorbing materials, numbering different types of absorbing materials respectively, and establishing an absorbing material database; wherein the electromagnetic parameters include at least one of the following: relative dielectric constant, relative magnetic permeability.
[0043] Optionally, by collecting electromagnetic parameters of different types of absorbing materials, a database of absorbing materials is established. For example, 7 types of absorbing materials are collected to establish a database of absorbing materials, and they are numbered respectively, as shown in Table 1:
[0044] Material No. Relative dielectric constant Relative magnetic permeability #1 (39.197-32.130i,38.420-31.699i,...) (0.970-0.165i,0.964-0.163i,...) #2 (2.822-0.147i,2.822-0.147i,...) 1 #3 (5.316-0.321i,5.284-0.251i,...) 1 #4 (9.569-2.305i,9.540-2.218i,...) 1 #5 (3.512-0.071i,3.500-0.088i,...) 1 #6 (18.128-0.761i,18.114-0.783i,...) 1 #7 (49.391-58.174i,49.241-57.037i,...) 1
[0045] According to the combination of the 7 materials in Table 1, the structures formed by the broadband multilayer absorbing material are three-layer, four-layer and five-layer structures respectively.
[0046] Example 1
[0047] Figure 2A schematic diagram of the structure of the multilayer absorbing material designed for the embodiment of the present application is shown in FIG. Figure 2 As shown, this embodiment 1 provides a three-layer structure composed of three absorbing materials, and the thicknesses thereof are d1 = 3.40 mm, d2 = 3.15 mm, and d3 = 0.90 mm respectively.
[0048] Figure 3 A schematic diagram of the wave absorbing effect of the three-layer wave absorbing material provided in the embodiment of the present application is shown in FIG. Figure 3 As shown in the figure, for the three-layer structure, the target frequency band for optimization is set to 4-8 GHz, and the target reflection loss is -5 dB. Within the target frequency band, the average reflection loss is -4.95 dB, and the minimum value can reach -5.40 dB.
[0049] Therefore, the three-layer structure absorbing material optimized by Example 1 of the present application has a better absorbing bandwidth effect.
[0050] Example 2
[0051] Figure 2 A schematic diagram of the structure of the multilayer absorbing material designed for the embodiment of the present application is shown in FIG. Figure 2 As shown, this embodiment 2 provides a four-layer structure composed of four absorbing materials, and the thicknesses thereof are d1 = 3.29 mm, d2 = 1.36 mm, d3 = 1.72 mm and d4 = 4.46 mm respectively.
[0052] Figure 4 A schematic diagram of the wave absorbing effect of the four-layer wave absorbing material provided in the embodiment of the present application is shown in FIG. Figure 4 As shown in the figure, for the four-layer structure, the target frequency band for optimization is set to 8-18 GHz, and the target reflection loss is -10 dB. Within the target frequency band, the average reflection loss is -9.91 dB, and the minimum value can reach -10.82 dB.
[0053] Therefore, the four-layer structure absorbing material optimized by Example 2 of the present application also has a good absorbing bandwidth effect.
[0054] Example 3
[0055] Figure 2 A schematic diagram of the structure of the multilayer absorbing material designed for the embodiment of the present application is shown in FIG. Figure 2 As shown, this embodiment 3 provides a five-layer structure composed of five kinds of absorbing materials, and the thicknesses thereof are d1=3.67mm, d2=3.50mm, d3=2.34mm, d4=1.26mm and d5=4.88mm respectively.
[0056] Figure 5 A schematic diagram of the absorbing effect of the five-layer absorbing material provided in the embodiment of the present application is shown in FIG. Figure 5As shown in the figure, for the five-layer structure, the target frequency band for optimization is set to 2-18 GHz, and the target reflection loss is -12 dB. Within the target frequency band, the average reflection loss is -11.03 dB, and the minimum value can reach -25.84 dB.
[0057] Therefore, the five-layer structure absorbing material optimized by Example 3 of the present application also has a good absorbing bandwidth effect.
[0058] It should be noted that the term "including" and its variations used in the embodiments of the present application are open inclusions, that is, "including but not limited to". The term "based on" means "based at least in part on". The term "one embodiment" means "at least one embodiment"; the term "another embodiment" means "at least one other embodiment"; the term "some embodiments" means "at least some embodiments". The modifications of "one" and "multiple" mentioned in the embodiments of the present application are illustrative and not restrictive. Those skilled in the art should understand that unless otherwise clearly indicated in the context, it should be understood as "one or more".
[0059] The various steps described in the method implementation methods provided in the embodiments of the present application can be performed in different orders and / or in parallel. In addition, the method implementation methods may include additional steps and / or omit the steps shown. The scope of protection of the present application is not limited in this respect.
[0060] The term "embodiment" in this specification refers to specific features, structures or characteristics described in conjunction with the embodiment that can be included in at least one embodiment of the present application. The appearance of this phrase in various places in the specification does not necessarily mean the same embodiment, nor does it mean that it is mutually exclusive with other embodiments and is independent or optional. The various embodiments in this specification are described in a related manner, and the same or similar parts between the various embodiments refer to each other. In particular, for the device, equipment, and system embodiments, since they are basically similar to the method embodiments, the description is relatively simple, and the relevant parts refer to the partial description of the method embodiment.
[0061] The above-mentioned embodiments only express several implementation methods of the present application, and the descriptions thereof are relatively specific and detailed, but they cannot be understood as limiting the scope of patent protection. It should be pointed out that, for a person of ordinary skill in the art, several variations and improvements can be made without departing from the concept of the present application, and these all belong to the scope of protection of the present application. Therefore, the scope of protection of the present application shall be subject to the attached claims.
Claims
1. A method for optimizing a broadband multilayer absorbing material, characterized in that: include: The thickness of each layer of the broadband multilayer absorbing material is optimized by using the Levenberg–Marquardt algorithm to obtain the optimal thickness value of the broadband multilayer absorbing material; wherein the steps of the optimization process are: S1: Setting the objective function F, the parameter initial value X0 and the maximum number of iterations; wherein the parameter initial value is the thickness initial value; S2: Calculate the residual r(X) and Jacobian matrix J(X) under the current parameters; S3: Using the iterative formula d K+1 =d K -(J T J+λI) -1 J T r calculates the update direction; where I is the unit matrix and λ is the damping factor; S4: Update parameter X new =X old +d; S5: Calculate the new residual r(X new ), and optimize the objective function F so that the objective function F is minimized; S6: Determine whether the number of iterations reaches the maximum number of iterations or whether the accuracy of the optimization result reaches the set accuracy; if so, output the optimal parameter; wherein the optimal parameter is the optimal thickness value; if not, execute S7; S7: Determine r(X new ) is less than r(X old ); if so, accept the update X new , reduce the damping factor λ and execute S2; if not, increase the damping factor λ and keep X old , and execute S3.
2. The optimization method of broadband multilayer absorbing material according to claim 1, characterized in that: The expression of the objective function F is: Among them, RL is the reflection loss within the target frequency band; R0 is the target reflection loss; r is the residual.
3. The optimization method of broadband multilayer absorbing material according to claim 2, characterized in that: When the structure of the broadband multi-layer absorbing material is a three-layer structure, the target frequency band of the three-layer structure is 4 to 8 GHz, and the target reflection loss is -5 dB.
4. The optimization method of broadband multilayer absorbing material according to claim 2, characterized in that: When the structure of the broadband multi-layer absorbing material is a four-layer structure, the target frequency band of the four-layer structure is 8 to 18 GHz, and the target reflection loss is -10 dB.
5. The optimization method of broadband multilayer absorbing material according to claim 2, characterized in that: When the structure of the broadband multi-layer absorbing material is a five-layer structure, the target frequency band of the five-layer structure is 2 to 18 GHz, and the target reflection loss is -12 dB.
6. The optimization method of broadband multilayer absorbing material according to claim 1, characterized in that: When the structure of the broadband multilayer absorbing material is a three-layer structure, the optimized thickness range of the three-layer structure is 0 to 4 mm; when the structure of the broadband multilayer absorbing material is a four-layer structure or a five-layer structure, the optimized thickness range of the four-layer structure or the five-layer structure is 0 to 5 mm.
7. The optimization method of broadband multilayer absorbing material according to claim 6, characterized in that: The thicknesses of the three-layer structure are 3.40mm, 3.15mm and 0.90mm respectively. Within the target frequency band, the average reflection loss is -4.95dB, and the minimum value reaches -5.40dB; the thicknesses of the four-layer structure are 3.29mm, 1.36mm, 1.72mm and 4.46mm respectively. Within the target frequency band, the average reflection loss is -9.91dB, and the minimum value reaches -10.82dB; the thicknesses of the five-layer structure are 3.67mm, 3.50mm, 2.34mm, 1.26mm and 4.88mm respectively. Within the target frequency band, the average reflection loss is -11.03dB, and the minimum value reaches -25.84dB.
8. The optimization method of a broadband multilayer absorbing material according to any one of claims 1 to 7, characterized in that: The method further comprises: Collect electromagnetic parameters of different types of absorbing materials, number the different types of absorbing materials respectively, and establish an absorbing material database; wherein the electromagnetic parameters include at least one of the following: relative dielectric constant and relative magnetic permeability.