Electromagnetic inverse scattering imaging-oriented electromagnetic camouflage metamaterial structure design method

Abstract

The invention relates to the technical field of electromagnetic shielding, in particular to an electromagnetic camouflage metamaterial structure design method for electromagnetic inverse scattering imaging, which comprises the following steps of: regulating and controlling the arrangement structure of a reflection unit by adjusting the arrangement mode of a supercell array; a one-dimensional vector is adopted to code grid states from a bottom layer unit cell to an upper layer unit cell, and different topological structures in the supercell are represented; copying and arranging the basic scattering units to form a periodic scattering array; setting target dielectric constant distribution according to the disguised imaging requirement; an error threshold is introduced to reduce the simulation calculation overhead; modeling and simulating metamaterial structures corresponding to different structure codes by utilizing a binary quantum particle swarm optimization algorithm, and realizing optimization design of the electromagnetic camouflage metamaterial structure by iteratively updating population individuals. According to the invention, a functional metamaterial structure for an interference imaging system is constructed by combining the regulation and control capability of the metamaterial on the wavefront of electromagnetic waves, and aims to realize misleading of radar imaging and detection systems.

Description

Technical Field

[0001] This invention relates to the field of electromagnetic shielding technology, and in particular to a method for designing electromagnetic camouflage metamaterial structures for electromagnetic backscattering imaging. Background Technology

[0002] With the development of multi-dimensional detection technologies such as radar, infrared, and acoustic waves, electromagnetic shielding chambers, in addition to requiring high shielding effectiveness, also need to integrate active stealth or camouflage functions to target enemy positional detection, thereby achieving systematic evasion, interference, and misdirection against specific detection methods. Electromagnetic scattering refers to the phenomenon where the propagation direction or wave characteristics of electromagnetic waves change when they encounter an object. It is mainly divided into forward scattering and inverse scattering problems. The forward scattering problem involves solving for the distribution and intensity characteristics of the scattered field after the interaction between the electromagnetic wave and the object, given the electromagnetic properties of the target object (such as dielectric constant, conductivity, and permeability) and the incident wave parameters (such as frequency, incident direction, and polarization). The inverse scattering problem, on the other hand, involves inferring the spatial distribution information, geometric shape, and position characteristics of the object based on the scattered field data measured around it.

[0003] Metamaterials, with their unique wavefront encoding capabilities, can precisely control the amplitude, phase, and direction of the scattered field without altering the physical structure of the target. Through meticulous design of the scattering characteristics, they can effectively "deceive" external imaging systems, causing them to misidentify the target object as having a different, predetermined shape or properties during perception. This introduces controllable biases into the object's image reconstruction, achieving electromagnetic camouflage. Therefore, a camouflage strategy based on metamaterials is needed to shield the target and actively create false information. Summary of the Invention

[0004] To address the aforementioned technical problems, this invention provides a method for designing electromagnetic camouflage metamaterial structures for electromagnetic backscattering imaging. This invention leverages the metamaterial's ability to manipulate electromagnetic wavefronts to construct a class of functionalized metamaterial structures for interfering with imaging systems, aiming to mislead radar imaging and detection systems.

[0005] The technical means employed in this invention are as follows: A method for designing electromagnetic camouflage metamaterial structures for electromagnetic backscattering imaging includes: adjusting the arrangement of reflective units by modifying the supercell array; encoding the grid state from the bottom unit cell to the top unit cell using a one-dimensional vector to characterize different topological structures in the supercell; replicating and arranging the basic scattering units along the horizontal and vertical axes in a two-dimensional plane to form a periodic scattering array; setting the target dielectric constant distribution according to the requirements of camouflage imaging during the imaging process; introducing an error threshold to reduce simulation computation overhead; and using the Binary Quantum Particle Swarm Optimization (BQPSO) algorithm as the optimization algorithm to model and simulate the metamaterial structures corresponding to different structure codes, and achieving optimized design of the electromagnetic camouflage metamaterial structure by iteratively updating the population individuals.

[0006] Furthermore, the method of adjusting the arrangement of the supercell array to control the layout of the reflective units specifically includes: dividing the supercell design region into two single-cell design regions of the same height, each with a size of a×b×h, corresponding to the bottom and upper layers of the supercell structure respectively; each single-cell design region is discretized into several grid units for arranging reflective units.

[0007] Furthermore, the different topological structures in the supercell are represented by a one-dimensional vector X to encode the grid state from the bottom unit cell to the top unit cell. Each element xi in the vector X is a binary variable used to indicate whether the corresponding sub-grid position is occupied by coded material.

[0008] Furthermore, the step of replicating and arranging the basic scattering units along the horizontal and vertical axes in a two-dimensional plane to form a periodic scattering array specifically includes: constructing a complete three-dimensional scattering structure by three-dimensional stitching of the array; obtaining the scattering field distribution corresponding to the three-dimensional structure using the forward electromagnetic scattering numerical calculation method; and inverting the two-dimensional dielectric constant distribution of the three-dimensional structure using the electromagnetic inverse scattering BIM imaging method.

[0009] Furthermore, the setting of the target dielectric constant distribution specifically includes: during the imaging process, the imaging area is discretized into n sub-imaging units, and it is assumed that the dielectric constant within each sub-unit is uniformly distributed. According to the requirements of camouflage imaging, the target dielectric constant distribution is set, that is, each sub-unit is assigned an expected dielectric constant value; an optimization objective function is defined to accumulate the difference between the expected dielectric constant value and the actual inverted dielectric constant value in each sub-imaging unit.

[0010] Furthermore, the error threshold T is used to reduce the computational overhead of simulation. When the optimization target is less than T, the current structure is considered to meet the design requirements, and the optimization iteration is terminated in advance.

[0011] Compared with the prior art, the present invention has the following advantages: This invention provides a method for designing electromagnetic camouflage metamaterial structures for electromagnetic backscattering imaging. Based on the application requirements of interfering with electromagnetic backscattering imaging, a functionalized camouflage metamaterial structure is proposed. This structure modulates the scattering characteristics of the target surface, causing deviations in the inverted imaging results, thereby misleading the target at the observation end. The structure is simulated and verified on an electromagnetic imaging platform constructed using the Born Iterative Method (BIM). The designed metamaterial-guided imaging algorithm misidentifies the target as a preset false shape, thus misleading the radar image. Attached Figure Description

[0012] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0013] Figure 1 This is a flowchart of the electromagnetic camouflage metamaterial structure design method for electromagnetic backscattering imaging in this invention.

[0014] Figure 2 This is a schematic diagram of different supercells and scattering units in this invention.

[0015] Figure 3 This is a schematic diagram of the topology-optimized scattering structure of the present invention.

[0016] Figure 4 This is a discretized dielectric constant distribution diagram of the target camouflage object in an embodiment of the present invention.

[0017] Figure 5 This is an example of a camouflaged metamaterial two-dimensional structure and its corresponding electromagnetic imaging in an embodiment of the present invention. Detailed Implementation It should be noted that, unless otherwise specified, the embodiments and features described in the present invention can be combined with each other. The present invention will now be described in detail with reference to the accompanying drawings and embodiments.

[0018] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. The following description of at least one exemplary embodiment is merely illustrative and is in no way intended to limit the present invention or its application or use. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0019] It should be noted that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the scope of exemplary embodiments according to the invention. As used herein, the singular form is intended to include the plural form as well, unless the context clearly indicates otherwise. Furthermore, it should be understood that when the terms "comprising" and / or "including" are used in this specification, they indicate the presence of features, steps, operations, devices, components, and / or combinations thereof.

[0020] Unless otherwise specifically stated, the relative arrangement, numerical expressions, and values ​​of the components and steps described in these embodiments do not limit the scope of the invention. It should also be understood that, for ease of description, the dimensions of the various parts shown in the drawings are not drawn to actual scale. Techniques, methods, and devices known to those skilled in the art may not be discussed in detail, but where appropriate, such techniques, methods, and devices should be considered part of the specification. In all examples shown and discussed herein, any specific values ​​should be interpreted as merely exemplary and not as limitations. Therefore, other examples of exemplary embodiments may have different values. It should be noted that similar reference numerals and letters in the following figures denote similar items; therefore, once an item is defined in one figure, it need not be further discussed in subsequent figures.

[0021] like Figure 1 As shown, this invention provides a method for designing electromagnetic camouflage metamaterial structures for electromagnetic backscattering imaging. To achieve scattering characteristics different from conventional objects, the metamaterial structure requires meticulous design, particularly in controlling the arrangement of the reflective cells. By adjusting the arrangement of the supercell array, the overall scattering response characteristics can be effectively altered.

[0022] By adjusting the arrangement of the supercell array, the layout structure of the reflective units is controlled. In a preferred embodiment of the present invention, the supercell design region is divided into two single-cell design regions of the same height, each with a size of a×b×h, corresponding to the bottom and upper layers of the supercell structure, respectively. Each single-cell design region is discretized into several grid units for arranging the reflective units.

[0023] A one-dimensional vector is used to encode the grid state from the bottom unit cell to the top unit cell to represent different topological structures in the supercell. In a preferred embodiment of the present invention, the different topological structures in the supercell are represented by encoding the grid state from the bottom unit cell to the top unit cell using a one-dimensional vector X. Each element xi in the vector X is a binary variable used to indicate whether the corresponding sub-grid position is occupied by coded material.

[0024] The basic scattering units are copied and arranged along the horizontal and vertical axes in a two-dimensional plane to form a periodic scattering array. In a preferred embodiment of the present invention, a complete three-dimensional scattering structure is constructed by three-dimensional stitching of the array. The scattering field distribution corresponding to the three-dimensional structure is obtained by using the forward numerical calculation method of electromagnetic scattering. The two-dimensional dielectric constant distribution of the three-dimensional structure is obtained by inversion using the electromagnetic inverse scattering BIM imaging method.

[0025] During the imaging process, a target dielectric constant distribution is set according to the requirements of camouflage imaging. In a preferred embodiment of the present invention, the imaging area is discretized into n sub-imaging units during the imaging process, and it is assumed that the dielectric constant within each sub-unit is uniformly distributed. According to the requirements of camouflage imaging, a target dielectric constant distribution is set, that is, a expected dielectric constant value is assigned to each sub-unit. Based on this, an optimization objective function is defined, and the difference between the expected dielectric constant value and the actual inverted dielectric constant value in each sub-imaging unit is accumulated.

[0026] An error threshold is introduced to reduce simulation computation overhead. In a preferred embodiment of the present invention, the error threshold T is used to reduce simulation computation overhead. When the optimization target is less than T, the current structure is considered to meet the design requirements, and the optimization iteration is terminated in advance.

[0027] In practice, the sum-of-squares form is more sensitive to amplifying the effects of larger local errors, thus prompting the optimization process to reduce the overall deviation more uniformly. Therefore, the difference is specifically the sum of squares of the differences between the corresponding sub-units, aiming to quantify the overall imaging error. By minimizing this objective function, the design of the scattering structure can be optimized, making the dielectric constant distribution obtained by inversion as close as possible to the expected distribution, thereby achieving the desired camouflage imaging effect.

[0028] Using the Binary Quantum Particle Swarm Optimization (BQPSO) algorithm, metamaterial structures corresponding to different structural codes are modeled and simulated to calculate their scattering field characteristics. The relative permittivity distribution of each structure is obtained through BIM inverse scattering inversion. The obtained permittivity distribution is compared with a preset camouflage imaging target, and the difference between the two is calculated and used as an optimization evaluation index. By iteratively updating the population, the difference between the actual imaging effect and the expected camouflage target is continuously reduced, thereby achieving the optimized design of the electromagnetic camouflage metamaterial structure.

[0029] Example Metamaterial structures were designed for electromagnetic camouflage applications at specific frequencies, with the goal of interfering with BIM imaging algorithms at 10 GHz to achieve electromagnetic camouflage. Figure 2As shown, by combining several supercells with different coding sequences to form a basic scattering unit, precise control of electromagnetic wave scattering characteristics can be achieved. The scattering unit contains three supercell structures with different coding sequences. Each supercell is further subdivided into two single-cell design regions, with a single-cell size of 60mm × 32mm × 5mm. The design domain of each single cell is discretized into 15 × 8 subgrids to determine whether to place reflective units. In the simulation, the relative permittivity of the scattering unit structure is set to 2. Basic scattering units are replicated and arranged along the x and y axes in a two-dimensional plane to form a periodic scattering array. Subsequently, three-dimensional stitching is performed, as shown... Figure 3 As shown, a complete three-dimensional rectangular sleeve scattering structure was constructed, with overall structural dimensions of 108.6mm × 96.6mm × 180.6mm.

[0030] like Figure 4 As shown, the expected dielectric constant distribution of the camouflaged target is defined within a 200mm × 200mm imaging region. This region is divided into individual 10mm × 10mm sub-grids, forming a total of 400 sub-grids to describe the detailed features of the camouflaged target. In the target dielectric constant distribution setting, if a sub-grid area is filled in yellow, the corresponding expected dielectric constant is set to 2; if a sub-grid area is filled in white, the corresponding expected dielectric constant is set to 1. In this way, the spatial characteristics of the camouflaged target are accurately expressed using a discretized dielectric constant distribution.

[0031] like Figure 5 As shown, the topology-optimized metamaterial 3D structure has an overall rectangular sleeve shape, but it exhibits a ring-shaped feature in electromagnetic backscattering imaging, which is highly similar to the shape of the pre-set target camouflage object. This result demonstrates that the metamaterial structure designed using the proposed topology optimization method can effectively control scattering characteristics, achieving precise control over electromagnetic imaging results and thus achieving the desired camouflage effect.

[0032] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for designing electromagnetic camouflage metamaterial structures for electromagnetic backscattering imaging, characterized in that, include: The arrangement of the reflective units can be controlled by adjusting the arrangement of the supercell array; One-dimensional vectors are used to encode the grid state from the bottom unit cell to the top unit cell to represent different topological structures in the supercell; The basic scattering units are copied and arranged along the horizontal and vertical axes in a two-dimensional plane to form a periodic scattering array; During the imaging process, the target dielectric constant distribution is set according to the requirements of camouflage imaging; Introducing an error threshold reduces simulation computation overhead; Using the binary quantum particle swarm optimization algorithm (BQPSO) as the optimization algorithm, we model and simulate metamaterial structures corresponding to different structural codes. By iteratively updating the population individuals, we achieve the optimized design of electromagnetic camouflage metamaterial structures.

2. The method for designing electromagnetic camouflage metamaterial structures for electromagnetic backscattering imaging according to claim 1, characterized in that, The method of adjusting the arrangement of the supercell array to regulate the layout of the reflective units specifically includes: The supercell design region is divided into two single-cell design regions of the same height, each with a size of a×b×h, corresponding to the bottom and upper layers of the supercell structure, respectively; each single-cell design region is discretized into several grid elements for arranging reflection elements.

3. The method for designing electromagnetic camouflage metamaterial structures for electromagnetic backscattering imaging according to claim 1, characterized in that, The different topological structures in the supercell are represented by a one-dimensional vector X, which encodes the grid state from the bottom unit cell to the top unit cell. Each element xi in the vector X is a binary variable used to indicate whether the corresponding sub-grid position is occupied by coded material.

4. The method for designing electromagnetic camouflage metamaterial structures for electromagnetic backscattering imaging according to claim 1, characterized in that, The step of replicating and arranging the basic scattering units along the horizontal and vertical axes of a two-dimensional plane to form a periodic scattering array specifically includes: A complete three-dimensional scattering structure is constructed by stitching together the arrays in three dimensions. The scattering field distribution corresponding to the three-dimensional structure is obtained by using the forward electromagnetic scattering numerical calculation method. The two-dimensional dielectric constant distribution of the three-dimensional structure is obtained by using the electromagnetic inverse scattering BIM imaging method.

5. The method for designing electromagnetic camouflage metamaterial structures for electromagnetic backscattering imaging according to claim 1, characterized in that, The specified target dielectric constant distribution specifically includes: During the imaging process, the imaging area is discretized into n sub-imaging units, and it is assumed that the dielectric constant within each sub-unit is uniformly distributed. According to the requirements of camouflage imaging, the target dielectric constant distribution is set, that is, the expected dielectric constant value is assigned to each sub-unit. An optimization objective function is defined to accumulate the difference between the expected dielectric constant value and the actual inverted dielectric constant value in each sub-imaging unit.

6. The method for designing electromagnetic camouflage metamaterial structures for electromagnetic backscattering imaging according to claim 1, characterized in that, The error threshold T is used to reduce the computational overhead of simulation. When the optimization target is less than T, the current structure is considered to meet the design requirements, and the optimization iteration is terminated in advance.

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