Metasurface Structure Design Based On Multi-layer Composite Structure

As a new artificially designed material,metasurface provides more design directions for electromagnetic stealth technology.And metasurface has the characteristics of easy design and flexible control.Starting from actual use,the design of a metasurface based on Al₂O₃ plays the role of RCS reduction.At the same time,the multilayer composite structure,which composed of absorbing materials and metasurface,can effectively optimize the bandwidth of a single metasurface and the RCS reduction effect.Based on the generalized Snell principle and the design principle of the phase difference angle,metasurface based on circular and petal-like metal patterns is designed to work in practice.The simulation and sample tests prove that the design can work well from 8GHz to 12GHz.The checkerboard structure can meet actual use（the reduction value of single station RCS can reach more than 10dB）.Then using the designed unit and starting from the principle of random coding,we can get different random coding metasurfaces.And it is explored that when the ratio of random coding is the same,the single station RCS are similar.Compared with the checkerboard structure,the designed random code metasurfaces have better effect in RCS reduction in the 8GHz-12GHz.And also the designed random coding metasurface expands the continuous 10dB bandwidth,optimizes the RCS reduction effect of the metasurface.The random coding metasurface provides another idea for the design of RCS reduction metasurface.Based on the principle of loss-scattering,different absorbing materials and their checkerboard metasurfaces are formed into different multilayer composite structures.And the electromagnetic loss function of the absorbing materials and the scattering function of the metasurface are superimposed.Compared with single metasurface,the multi-layer composite structure optimizes the reduction effect of a single checkerboard,which not only broadens the continuous reduction bandwidth of RCS by more than10dB,but also increases the minimum RCS reduction.At the same time,through the use of three different absorbing materials,including Ba-W ferrite,ZnFe₂O₄ and CrAlC,the multi-layer composite structure shows different results in single station RCS reduction.And the stimulation results show the three kinds of absorbing materials have different effect in multi-layer composite metasuface and different working mechanism.The anaylsis shows the requirement of the microwave absorbing material forming a multilayer composite structure on the surface and also provides guidance for the design of the multilayer composite structure.