CN-122026123-A - Random grid structure-based diffuse reflection surface design method

CN122026123ACN 122026123 ACN122026123 ACN 122026123ACN-122026123-A

Abstract

The invention discloses a diffuse reflection surface design method based on a random grid structure. Through the combined design of the conductive random grid and the dielectric plate, the diffuse reflection of the incident electromagnetic wave in a wider frequency band can be realized. Compared with the traditional coding diffuse reflection surface, the method has the advantages of no dependence on strict phase relation among array units and no tangential size limitation, and can be conveniently applied to curved surfaces.

Inventors

HUANG MINJIE
WANG XINGYU
DU HUAFEI

Assignees

北京航空航天大学

Dates

Publication Date: 20260512
Application Date: 20260226

Claims (5)

1. A diffuse reflection surface design method based on a random grid structure is characterized in that: the method comprises the following steps: Step 1, determining a required frequency band and an available medium, and determining structural parameters and medium thickness of a random grid; And 2, generating and modeling a random grid, namely calculating grid generation parameters according to design requirements by adopting a random grid structure generation method for simulating a cell growth process or a random grid generation method based on natural random pattern feature extraction, further generating a random grid pattern and establishing an electronic model. And 3, determining a preparation process of the random grid/medium mixed structure, namely selecting to prepare a conductive layer on the surface of a medium which is tightly attached to the conductive grid layer and has good strength, the surface of which is easy to metalize and etch according to the section structure of the random grid, preparing the conductive layer by adopting methods such as prepreg lamination, chemical plating, vapor deposition or vacuum sputtering, and the like, wherein the thickness of the conductive layer is not less than 1.5 times of the skin depth, and preparing the conductive layer grid by adopting chemical etching or laser etching according to the precision requirement. And 4, metallizing the surface of the medium, namely processing the selected conductive attached medium plate to a set thickness according to a design scheme, and preparing the conductive layer by adopting the method determined in the step 3. And 5, preparing a medium surface grid, namely generating a film (or an input file required by laser etching) required by chemical etching according to the random grid pattern electronic model in the step 2, and etching the random grid pattern on the conductive layer through a chemical etching (or laser etching) process. And 6, compounding a random grid structure and a dielectric layer, namely adopting a mode of alternately superposing a dielectric layer and a grid layer aiming at the composite structure of more than 2 layers of random grids, firstly preparing a first layer of grid on the surface of a substrate dielectric plate, covering the dielectric layer, then preparing a second layer of grid by adopting the etching method determined in the step 3, covering the dielectric layer and preparing a third layer of grid, and realizing interlayer close fit through a hot pressing process in the compounding process so as to ensure the structural integrity. And 7, testing and verifying.
2. A method for designing a diffuse reflection surface based on a random grating structure according to claim 1, wherein the random grating is used as a source of diffuse reflection characteristics.
3. The method for designing a diffuse reflection surface based on a random grating structure according to claim 1, wherein the step 1 is characterized in that different parameters of grating nesting or stacking can be adopted to widen the diffuse reflection frequency band.
4. The method for designing the diffuse reflection surface based on the random grating structure according to claim 1, wherein the random grating generation method simulating the growth process of the unit cells is adopted in the step 2, so that the random grating structure can be controllably generated, and the designability of the random diffuse reflection surface is ensured.
5. The method for designing the diffuse reflection surface based on the random grating structure according to claim 1, wherein the random grating generation method based on natural random pattern feature extraction is adopted in the step 2, so that accurate reconstruction of random features of the bionic pattern can be realized, and the random diffuse reflection surface has statistical randomness and structural stability of the natural pattern and good electromagnetic and optical performance synergism.

Description

Random grid structure-based diffuse reflection surface design method Technical Field The invention relates to the field of communication and electromagnetic filtering, in particular to a diffuse reflection surface design method based on a random grid structure. Background Random grid structures are a type of surface metallization or conductivity, but are structures that are covered with a number of irregularly shaped, randomly distributed voids. The structure is electromagnetically transparent in a high frequency band, the ideal conductor is similar in appearance and is mirror image total reflection in a low frequency band, and certain reflection/transmission behavior abnormality is shown in a middle frequency band, wherein the reflection/transmission rate fluctuates along with the change of frequency, the phase changes and grating lobes with random directions exist. By utilizing the characteristics, a thin layer structure with diffuse reflection characteristic can be designed based on a random grid, the radar scattering characteristic attenuation of the target is realized through diffuse reflection electromagnetic waves, and the probability of the target being captured by radar detection is reduced. The diffuse reflection surface of the traditional radar wave band mostly adopts a coding type structure. In order to ensure the phase relationship, the tangential dimension of the array element is large and is difficult to make into a curved surface. The diffuse reflection surface based on the random grid structure has strong random shape and no strict phase requirement, so that the tangential dimension is easy to miniaturize and can be conveniently applied to curved surfaces without complex design for the curved surfaces, and the application flexibility of the diffuse reflection surface is obviously higher than that of the coded diffuse reflection surface. Disclosure of Invention The invention aims to provide a diffuse reflection surface design method based on a random grid structure, which realizes the efficient diffuse reflection of normal incidence electromagnetic waves in a broadband through the cooperative design of a random grid and a dielectric plate. In order to achieve the above purpose, the technical scheme of the invention is as follows. A diffuse reflection surface design method based on a random grid structure comprises the following steps: Step 1, determining a required frequency band and available media, determining structural parameters of a random grid and media thickness, wherein the random grid can generate a normal incidence single-station RCS reduction effect of 3-9dB approximately every 1 layer of random grid, the media thickness is about 0.7pi of phase thickness or 0.17λ 0(λ0 of electrical thickness is the wavelength in the media), and the aperture perimeter is about 0.8-1.2λ 0. And 2, generating and modeling a random grid, and adopting a random grid structure generating method for simulating a unit cell growth process. The method comprises the steps of establishing a coordinate system in a plane area of a random grid to be generated, dividing the area into regular square grids, randomly throwing seed crystals on the grids, establishing a growth rule of the seed crystals, enabling all the seed crystals to grow into unit cells freely according to the growth rule until the whole area is paved, extracting grid coordinates of the unit cell boundary, fitting the grid coordinates into a curve boundary, obtaining a grid boundary on the random grid structure, and finally obtaining the grid structure with good randomness by utilizing grid boundary information. And 3, determining a preparation process of the random grid/medium mixed structure, namely selecting to prepare a conductive layer on the surface of a medium which is tightly attached to the conductive grid layer and has good strength and easy surface metallization and etching according to the section structure of the random grid, preparing the conductive layer by adopting methods such as chemical plating, prepreg lamination, vapor deposition or vacuum sputtering, wherein the thickness of the conductive layer is not less than 1.5 times of the skin depth, and preparing the conductive layer grid by adopting chemical etching or laser etching according to the precision requirement. Step 4, medium surface metallization, namely processing the selected conductive attached medium plate to a preset thickness according to a design scheme, and then carrying out metallization or film coating treatment on the surface of the medium plate to form a uniform conductive substrate, wherein the process flow of an available chemical plating method is shown as a figure 1, the process flow of an available prepreg lamination method is shown as a figure 2, and other vapor deposition or vacuum sputtering methods can refer to the preparation process flow of a mature copper film, a gold film or a silver film; And 5, preparing a grid on the surface of the medium, namel