Research On Application Of Flexible Checkerboard Conformal Metasurface Structures In RCS Reducation

With the continuous progress of radar detection technology,the survival capability of ships is seriously threatened,therefore,enhancing the stealth of ships,improving their protection and countermeasures as well as enhancing their survivability has become a major focus of research topics.Radar cross section(RCS)is a key indicator of radar stealth capability,and metasurface technology has a broad research prospect as an RCS reduction technology with wide operating band and excellent stealth performance.In the past few years,most of the studied metasurface design performance has limited application scenarios and previous researched works have limitations in terms of RCS reduction values,fractional bandwidth and different geometries of conformal metasurface.To address these issues,this paper designs a metasurface with large scaling amplitude,wide scaling bandwidth,light weight,single-layer structure,good polarization stability,and flexible and easy conformal shape with 20 d B RCS scaling in the 6 GHz-12 GHz.In addition,the RCS reduction capability of conformal metasurface with different geometries is verified considering in practical applications,and the possibility of achieving ship stealth is verified in ship surface cladding.The main research elements are as follows:First,a method combining both absorption and phase cancelation principles is used to design two basic cells of single-layer absorbing metasurface,which satisfy broadband RCS reduction of 10 d B with phase difference of 180±37°.Based on the array theory,the radar stealth principle of the checkerboard metasurface is analyzed;theoretically,the mathematical model of surface impedance and reflection phase/amplitude is established by analyzing the surface impedance conditions of the 20 d B RCS reduction of the two basic cells considering both absorption and phase cancellation;through electromagnetic simulation software,the parameters in the cells are simulated and analyzed on the reflection amplitude,reflection phase and surface impedance.Finally,based on the simulation results,two kinds of basic metasurface units with different reflection phase and reflection amplitude are designed.Secondly,different checkerboard metasurface array layouts are designed using the basic metasurface unit to achieve RCS reduction of 20 d B in the band range of 6.1 GHz-12.5 GHz,and the performance of the designed checkerboard metasurface under different conformal surfaces is analyzed.For different scenario application requirements,different arrays are designed to meet the maximum performance of the checkerboard metasurface,and the basic number of array elements,array element shapes,and application scenarios are analyzed to compare the RCS reduction performance of three scenarios.For planar and column surface RCS reduction,considering the traditional square array metasurface can reach the target requirements;for dihedral angle shape,the incident wave will produce superposition after dihedral angle,staggered triangle array has good main and side flap reduction performance,it is adapted to the dihedral angle RCS reduction requirements.Third,the ship electromagnetic scattering characteristics are simulated to analyze the effects of different polarization methods,incident wave frequencies and different pitch angles on the ship RCS.For the sphere-like and saddle-surface deformation surfaces that appear in practical applications,the metasurface are conformal to the deformation surfaces,and the RCS reduction under multiple sets of curvature is studied for the deformation surfaces respectively.Finally,for shipboard strong scattering sources,the feasibility of RCS reduction on the metasurface is verified by comparing the RCS before and after the metasurface on the ship’s cladding.In conclusion,a wideband flexible checkerboard metasurface with excellent performance is designed in this paper,which has been successfully applied to RCS reduction of conformal metasurfaces with different geometric shapes,and it has shown the potential of improving ship stealth performance in the application of ship surface covering.This study provides useful reference and guidance for the development of ship stealth technology.