Studies On The Frequency Selective Rasorber And Its Miniaturization

With the continuous development of radar detection technology,the radar stealth performance of military units will largely determine their survival and combat capabilities in the future battlefield.Among them,the antenna system is a window for transmitting and receiving the electromagnetic signal,and the electromagnetic characteristics are more complex.How to guarantee the proper functioning of the antenna and the stealth against the enemy synchronously will become the focus of future research.The frequency selective rasorber,due to its in-band transmission with low insertion loss and out-of-band absorption,has begun to emerge in the stealth design of the antenna system.Compared with the FSS-loaded radome,it has more advantages in bistatic and wide-angle RCS reduction.Based on the working principle of FSS and radar absorber,this paper designs different FSRs with different structures and frequency response,and through its miniaturization design,the broadband absorption and grating lobe suppression have been achieved.The main work can be summarized as follows:(1)The basic configurations of FSS and structured radar absorbing material(RAM)are introduced.Based on the equivalent circuit model and transmission line theory,the electromagnetic characteristics and working mechanism of the FSS with low-pass,high-pass,band-pass,band-stop characteristics and Salisbury absorber,Jaumann absorber,circuit analog absorber were studied.The effects of different parameters on the frequency response of FSS and RAM have been analyzed.(2)Based on the working principle of FSS and circuit analog absorber.Two kinds of miniaturized FSRs,two-dimensional and three-dimensional,are designed.The main factors that affect the performance of transmission and absorption are analyzed,and the monostatic and bistatic RCS reduction capability and grating lobe suppression effect are verified.The designed two-dimensional FSR structure transmits electromagnetic waves in 2.6-3.6GHz,and absorbs electromagnetic waves in 6-19GHz.In the range of 6-19GHz,The reduction effect of the bistatic RCS achieved by FSR reaches more than 10d B,and no grating lobes are generated.Compared with the two-dimensional structure,the three-dimensional structure has a similar frequency response,but its response stability of various angles under TM polarization is improved.The three-dimensional structure can maintain the stability of the frequency response under TE and TM polarized waves with incident angles ranging from0°-30°.(3)In order to ensure the stability of the FSR frequency response stability and the further miniaturization of the unit structure,the idea of transferring the pressure of miniaturization design to multiple layers is proposed,and the FSR with multilayer composite structure is designed.The unit size is 0.041?₀×0.041?₀×0.106?₀.The transmission passband is from 2.08 to 2.82 GHz,and the relative bandwidth is 30.2%.The absorption band is 7.68-21.7GHz,and the relative bandwidth is 95.2%.Its frequency response has good stability to polarization and maintains the required stability when the oblique incidence angle is in the range of 0°-45°.The test results are basically consistent with the simulation results.(4)Two kinds of design ideas of FSRs with the property of transmission at high frequency and absorption at low frequency have been analyzed,and a new kind of FSR with1/4?short-circuit branches has been proposed.The absorption frequency band is from1.5GHz to 4.6GHz,and the transmission frequency band is in the range of 8-12GHz.While ensuring the absorption of electromagnetic waves at low frequency and broadband transmission at high frequency,the size of the FSR unit is compressed within 12mm by using the miniaturization design with pin structure,avoiding the generation of gate lobes and other problems.