Low RCS Antenna Technology Based On Electromagnetic Metamaterials

In the complex and changeable military war,military countries study and develop stealth technology to increase the survivability of weapons.Stealth technology,consisted of low observation technology and low probability interception technology,reduces the probability of our target being detected by the threatening radar,in the way of reducing the radar cross section(RCS)of targets.The excellent electromagnetic control ability of electromagnetic metamaterials can be used to reduce the radar cross section of targets,which shows broad application prospects in stealth technology and attracts extensive attention of scholars in the military field.In this thesis,an artificial magnetic conductor(AMC)and a polarization conversion metasurface(PCM)are designed,based on the antenna scattering theory and the basic theory of electromagnetic metamaterials.And the polarization conversion metasurface is applied to reduce the radar cross section of antennas.The main research work of this thesis can be summarized as follows:1.An artificial magnetic conductor metasurface is proposed to reduce RCS.Firstly,an artificial magnetic conductor unit with a quasi-cross structure is designed.The reflection phase difference between the perfect electrical conductor(PEC)and artificial magnetic conductor meets 180°±37°,whose band covers from 9GHz to 16.5 GHz.Then,the array of 6×6 AMC and the array of 6×6 PEC are arranged in checkerboard structure.Compared with the same size of the PEC,RCS has been reduced more than 10 d B by the designed checkerboard structure,whose band covers from 9.5GHz to 16GHz(relative bandwidth is about 51%).2.A single-layer polarization conversion metasurface for RCS reduction of antennas is proposed.Firstly,a PCM unit consisting of three rectangular resonators is designed.The polarization rotation bandwidth of the reflected wave covers from 7.6GHz to 13.4GHz.Then the array of 5×5 PCM and its mirror are arranged in checkerboard structure,which can reduce more than 5d B RCS,over the frequency band of 8.1GHz-13.4GHz(relative bandwidth is about 49.6%).The PCM is put on the microstrip antenna.While ensuring the radiation performance,the proposed antenna can achieve more than 5d B RCS reduction,over the frequency band of 8GHz-13.4GHz.Finally,the microstrip antenna put on the polarization conversion metasurface is fabricated and measured,and the measured results are consistent with the simulation results.3.A new type of double-layer polarization conversion metamaterial for RCS reduction of antennas is proposed.Firstly,a double-layer PCM unit is designed,which broadens the working bandwidth compared to the same size single-layer PCM unit.The polarization rotation bandwidth covers from 5.5GHz to 15.3GHz.Then two kinds PCM are designed.PCM I uses a cross structure,whose bandwidth of 5d B RCS reduction covers from 6.5GHz to 11.7GHz.PCM II uses a traditional chessboard structure,and its RCS reduced more than 5d B from 5.7GHz to 16 GHz.The PCM II is put on the microstrip antenna.While ensuring its radiation performance,the proposed antenna can reduce more than 5d B RCS from 6GHz to 16.5GHz.Finally,the microstrip antenna put on double-layer PCM is fabricated and measured,and the measured results are consistent with the simulation results.