Design And Research Of Reconfigurable Rasorber Loaded By Active Devices

The radar antenna system of aircraft and other weapon platforms provides most of the overall radar cross section(RCS).How to reduce the RCS of this part is the research emphasis in the field of electromagnetic stealth.Passive rasorber radomes based on frequency selective surface can realize out-of-band absorption and reduce the RCS of two stations while ensuring the normal operation of the antenna.With the development of information technology,the limitation of single function of passive rasorber is exposed gradually,and active rasorber is proposed to adapt to the requirements of complex electromagnetic environment.This thesis focuses on the reconfigurable rasorber and to realize the adjustable position of the passband to meet the working requirements and electromagnetic compatibility of radar in various frequency bands for the same antenna system.Firstly,this thesis introduces the rasorber equivalent circuit analysis method,analyzes the carrier transport mechanism of active devices,and classifies and compares the performance of the loading mode of bias network.Based on the transmission line theory and wave transmission mechanism of the first order frequency selective surface,a double sided frequency selective surface with variable capacitance diode loading is designed.Then,aiming at the first-order defects and the requirement of simplification of bias network,the wave-transmission layer is designed,and based on the theory of second-order band-pass spatial filte,the scheme of second-order passband tunable frequency selective surface loaded by variable capacitance diode is proposed,the passband window is adjustable from S to X band.According to the different conditions of positive and negative bias of PIN diode,a frequency selective surface is designed to switch back and forth between S and X bands.Narrowband consistency and high selectivity are obtained by sacrificing the number of tunings.The experimental results are in good agreement with the simulation in which the influence of internal resistance is included.Finally,the loading mode of PIN diode in LC resonanter is discussed,the performance of the new loading mode are compared with the traditional mode,and applied to the design of lossy layer.The compromise absorbing scheme of two modes is obtained by using python procedure for data processing.The designed lossy layer is combined with the aforesaid transmission layer to realize the reconfigurable rasorber with the passband switching between S and X band and absorption band in the C band.