Research On RCS Reduction Technology Based On Electromagnetic Matasurface

With the continuous development of modern electronic technology,stealth technology plays an important role in breaking through enemy radar detection.The improvement of various new radar technologies also has higher requirements for stealth technology.As a two-dimensional form of electromagnetic metamaterials,matasurface are currently the focus of research.Different amplitude,phase,and polarization patterns can be generated by adjusting the structure and arrangement of the matasurface.Using this feature,electromagnetic waves can be flexibly regulated,resulting in reduced radar scattering area in certain directions.This method of achieving electromagnetic stealth has extremely high military value,which can improve the survival probability of our equipment in the battlefield.Firstly,based on the phase modulation principle of matasurface for electromagnetic waves,this thesis has carried out a research on a polarization conversion structure for commonly used microwave frequency bands.On this basis,a frequency selective surface unit has been introduced to achieve dual band RCS reduction,and its structure has been designed,optimized,and verified.Secondly,an AMC cell structure was studied.Through optimization design,its RCS reduction function in broadband was verified,and its radiation performance was also improved to a certain extent.Finally,a liquid crystal material is introduced and a low RCS reflective reconfigurable digital coded matasurface based on liquid crystal material is proposed,which has the functions of RCS reduction,frequency band adjustment,and beam deflection.The main research content of this article is as follows:1.Firstly,a PCM unit with a similar "earth" shaped structure was simulated and designed.The PCM matasurface has a very high polarization conversion rate of incident electromagnetic waves.And pass the unit through 8×8 The checkerboard arrangement of the 8-array achieves RCS reduction of more than 10 d B in a wide band of 6.4-17.4GHz.Subsequently,based on the simplification of existing reduced frequencies,a low-pass response frequency selective surface was redesigned and introduced.By designing two structures that can achieve RCS reduction at different frequencies,and integrating the frequency selective surface with two PCM matasurface structures,RCS reduction of more than 10 d B in the two broad bands of 6.8-17.7 GHz and 23.5-37.5GHz was ultimately achieved,thereby achieving the function of achieving dual band broadband RCS reduction.2.Two types of AMC reflection units were designed by simulation,with a phase difference of 180° ± 37° in the frequency band range of 7.2GHz to 19.0GHz.Arranging them into a checkerboard to form an array,and simulating the impact of different n-value checkerboard arrangements on RCS reduction,we selected a better arrangement model,and verified the effect of AMC checkerboard RCS reduction based on 3D scattering diagrams.Subsequently,the antenna unit was integrated with the AMC checkerboard array.The radiation performance of the designed antenna was improved to a certain extent compared to the reference antenna,and the scattering performance was significantly improved compared to the reference antenna.In the frequency band range of 7.6-18.5GHz,the RCS was reduced by more than 10 d B.The entire design antenna loaded with the AMC checkerboard array has a good RCS reduction function.3.Firstly,the physical properties of nematic liquid crystal materials were studied,and a low RCS reflective reconfigurable digital coded matasurface based on liquid crystal materials was proposed.Different liquid crystal dielectric constants were generated by different bias voltages as the encoded "0" and "1" states.Through simulation and comparison between the non phase gradient unit and the digital coding unit in various arrangement modes,the RCS change image is obtained.By setting different pairs of liquid crystal dielectric constants,RCS reduction in different frequency bands within the X-band can be obtained,realizing the reconfigurable function of RCS reduction.Finally,according to the generalized Snell’s law,by adjusting the dielectric constant pair of liquid crystals,it is possible to output the reflected beam to a desired direction under different digital coding bases,obtaining a reflected wave at a specific angle,and achieving the beam deflection function of the transmitted wave.