Research On Optically Controlled Active Frequency Selective Surface

With the continuous development of the modern warfare,the demand for military stealth becomes more and more intense,Frequency Selective Surface(FSS)has been widely concerned by researchers with its unique electromagnetic properties.The Active Frequency Selective Surface(AFSS)further develops the research of FSS by loading active devices,enabling it to actively control its own electromagnetic performance and integrate multiple functions.It has a strong application potential in stealth absorbing,wireless communication,electromagnetic shielding and other aspects.In this thesis,the Optically Controlled Active Frequency Selective Surface(OCAFSS)is studied,and the electronic control method of the common AFSS is replaced by the illumination control method,so as to avoid the adverse effects brought by the feed network.The main work and innovation in this thesis are as follows:1)Research on Optically Controlled Microwave Switch(OCMS)The Equivalent Circuit Model(ECM)and the layered plasma model are used to analyze the OCMS,and the simulation electromagnetic model has been constructed.Some OCMS’s were made,which were tested by LED and laser respectively,and the influence of relevant factors on the performance of OCMS was analyzed.2)Research on band-pass/shielded OCAFSSBased on the research results of OCMS,a C-band OCAFSS with slit Jerusalem cross was designed.The function of OCAFSS is transmission in dark state,while shielding in bright state,with very stable polarization characteristics.The ECM is further analyzed and more accurate results are obtained.In order to test the OCAFSS,a Parallel-Plate Waveguide(PPW)was designed.The measurement results verify the design function of OCAFSS.3)Research on OCAFSS with continuous adjustment of absorbing rateBased on the idea of real-time control of RCS of our aircraft to pretend other aircraft so as to mislead enemy radar to make misidentification and formulate wrong strategy,an OCAFSS with continuous adjustment of absorbing rate /RCS is proposed.The OCAFSS works in the X-band and is reflective in dark state.With the enhancement of light,the wave absorption rate gradually increases and the RCS gradually decreases.After reaching the peak,the reflection characteristic will gradually appear again.In addition,this OCAFSS has low requirements for laser power and can still be optimized to obtain OCAFSS with lower requirements for photoconductivity.