Research On Reconfigurable Active Frequency Selective Surface

With the increasingly complex electromagnetic(EM)environment,the demand for electromagnetic control in all fields is more and more strong.However,Frequency Selective Surface(FSS),as one useful type of meta-material,has got much deep research.Active Frequency Selective Surface(AFSS)has manual active control or reconfigurable characteristic,which shows much application potential in realizing “smart” stealth radome(“smart-skin”),intelligence EMC,tunable absorber and others.Based on theoretical analysis and equivalent circuit model(ECM)method,this thesis will study and analyze the realization methods of AFSS,and manufactured samples and conducting the measurement,and finally quantitatively study the performance of AFSS stealth radome.The main work and several points of innovation are as following:1)Research on single-polarized and dual-polarized switchable AFSSTwo types of AFSS have been designed using full-wave simulation software to work for LTE-2.1GHz and LTE-2.6GHz separately,which the S21 parameter can be switched between transmission state and shielding state at working frequency point.The AFSS testing process for transmission coefficient is carried out in microwave anechoic chamber and the measurement results are compared with simulation results for verification.2)Research on programmable AFSS with multi-functionOne 2-bit AFSS has been constructed based on double-layer-coupled structure with four different characteristics: band-pass filter function(code-00),vertical polarization selection(code-01),horizontal polarization selection(code-10)and band-stop shield function(code-11).Moreover,this AFSS modified by loading PIN diodes and varactor diodes on different layers can combine switch and tune functions together.3)Research on the performance of A-sandwich radome loaded AFSS “smart-skin”One A-sandwich radome loaded square AFSS can achieve its transmission “window” shifting between C-band(6GHz)and X-band(9.5GHz),which equipped the radome with “smart-skin” ability.The biasing network is designed and optimized for the whole AFSS performance with good angle stability and polarization insensitive.4)Research on scattering characteristics of AFSS stealth radomeThrough analysis of RCS characteristic of polarization bar,the difference of RCS far-field results between two polarization incident wave onto polarization-sensitive structure can be understood.Scattering characteristic of 2-bit AFSS has been studied and RCS differences of four states has be compared to deepen understand 2-bit AFSS;finally,one ideal cone AFSS radome is simulated to quantitatively evaluate the stealth performance.