Low RCS Antenna Based On Electromagnetic Metasurface

In the complex modern electronic warfare,the stealth capability of aircraft and other weapon platforms has become a key factor to improve their own strike capability and ensure survival rate.In practice,the radar cross section(RCS)of weapon platform is usually reduced by modifying the shape of aircraft or coating radar absorbing materials.As the main scattering source of the weapon platform,how to effectively reduce RCS of the antenna under the premise of ensuring the radiation performance has been the focus of attention all over the world.Electromagnetic metasurface has the advantages of low loss,small size and easy integration,which can effectively regulate the electromagnetic wave,and provides a new research idea for the design of low RCS antenna.In this thesis,the application of electromagnetic metasurface in RCS reduction of the antenna is studied.The main contents are as follows:First,a low RCS microstrip antenna based on artificial magnet(AMC)is designed.Firstly,a polarization-sensitive AMC structure is designed,which can realize the phase difference ??(?)(143,217)between the two polarization directions in the 7.2-19.7 GHz range.Secondly,the 5×5 AMC cells are arranged in an orthogonal array to form a checkerboard shaped matesurface,and the RCS is reduced by at least 8d B in the frequency range from 7.2 to 19.7GHz.Finally,when the chessboard type metasurface is loaded around the microstrip antenna,the radiation gain of the microstrip antenna is significantly improved,and the antenna RCS is reduced by more than 5d B in the relative bandwidth range of 98%(7-20.5GHz).Second,a circularly polarized antenna array which reduce RCS in the operation band can based on Polarization Conversion Metasurface(PCM)is designed.Firstly,a PCM is designed to effectively reflect electromagnetic waves into cross-polarized waves in the4.8-6.7GHz band.By combining the checkerboard PCM metasurface with the antenna,the 10-d B impedance bandwidth of the 4×4 circularly polarized antenna array is 4-6.5GHz,the 3-d B axial ratio bandwidth is 4-6.3GHz,and the maximum radiation gain of the antenna is 16.2d Bi in the simulation.Moreover,antenna array can reduce the antenna RCS at 4-7GHz,and the maximum in-band RCS reduction is 15 d B.Finally,the circularly polarized antenna array is processed and measured,and the measured results are consistent with the simulation results.Third,a circularly polarized antenna array based on the checkerboard Absorptive Frequency Selective Surface(AFSS)with RCS reduction in and out of the operation band is designed.Firstly,an Absorptive Frequency Selective Surface(AFSS)is designed based on the method of scattering cancellation and absorption,which exhibits absorption-crosspolarized reflection-absorption frequency response.Secondly,the 2?2 AFSS unit and the slot antenna are jointly designed to radiate the circular polarization wave.Thirdly,the radiation and scattering performance of the periodic antenna array and the checkerboard antenna array are compared.The results show that the checkerboard antenna array can effectively reduce RCS in the frequency range from 2 to 9GHz while ensuring the radiation performance.Finally,the checkerboard antenna array is processed and measured,and the measured results are consistent with the simulation results.