The Research Of Fabrication Technique Of Paper Metamaterial Based On Drawing Method

Metamaterial is a composite material formed by the periodic arrangement of structural units designed by human.Its electromagnetic parameters can be controlled and it can show the electromagnetic characteristics that many materials in nature do not have.The Metasurface is an array of subwavelength electromagnetic elements arranged in two-dimensional period,which can be regarded as two-dimensional form of metamaterial.Compared with metamaterial,metasurface is small in volume,light in weight,more convenient and flexible.Metasurfaces have been widely used in military,communication and other fields.After decades of development,nowadays,the metamaterials are developing towards the direction of light,miniaturization and flexibility.Various kinds of metamaterial fabricated by new technology have emerged one after another.Paperbased metamaterial is one of the representatives.Paper-based metamaterial is a kind of metamaterial based on paper.The main preparation method of paper-based metamaterial is to print the metamaterial structure on paper by an ink-jet printer containing conductive ink.Compared with the metamaterial fabricated by PCB technology,paper-based metamaterials have the advantages of light weight,thin thickness,being foldable,easy conformal,low cost,no pollution in the process of processing,thus have broad application prospects.At present,ink-jet printing is the main preparation method of paper-based metamaterial.Because the ink-jet printing equipment is very expensive and the preparation of conductive ink is fairly complex,this paper explores a new method of using drawing method to fabricate paper-based metamaterials,which does not need expensive equipment and has a wider selection of drawing materials.We use the drawing robot as the drawing tool,use the ball point pen containing conductive ink to draw the conductors,use the mechanical pencil to draw the resistors,and explore how to improve the drawing quality.In order to verify the feasibility of the drawing method,we designed a paper-based absorber,a paper-based polarization-converter and a paperbased coding metamaterial,then we used the drawing method to fabricate them.The main content of this paper are as follows:1.The drawing robot is introduced as the drawing tool to realize the automation and high precision of the drawing process.This paper studies how to use ball point pen containing conductive ink to draw structure of conductors.This paper studies how to use mechanical pencil to draw resistors,including the graphite content of the pencil lead,the pressure applied on pencil during drawing and the number of times of repeated drawing.In order to build the model between the pressure and the resistance,we randomly select the pressure in a certain range to draw the resistors and measure their resistances,and then use linear regression model to fit the data to get the final model.In order to improve the durability and service life of the paper-based metamaterials,we introduced the plastic sealing to protect the paper-based metamaterials.2.In order to speed up the optimization of the absorber,we use the equivalent circuit to model the square loop absorber and optimize it according to the equivalent circuit model.In order to make the optimization process of metamaterial automatic and intelligent,we use Matlab to write the optimization program based on genetic algorithm.The optimization program can automatically call CST for simulation and optimize the parameters of metamaterial structure by genetic algorithm.The constraint relationship between parameters and the fitness function of genetic algorithm can be set freely,which is more flexible than the optimization module built in CST.3.Based on the equivalent circuit model,the paper-based square loop absorber is designed and fabricated by the drawing method.The test result shows the reflectivity below-10 d B in wide band under normal incidence.Based on the principle of filter,the paper-based polarization-converter is designed and fabricated by drawing method.The test result shows that the paper-based polarization-converter can realize polarization convertion with an efficiency of more than 90% in wide band.Combining the principle of random metasurface and absorber,a new type of paper-based coding metasurface is designed.The simulation results show that the paper-based coding metasurface can achieve RCS reduction of more than 10 d B in a wide band.