Analysis And Design Of Reconfigurable Frequency Selective Surface

Frequency Selective Surface,which has been widely used in stealth radome,is a two-dimensional periodic structure with band-pass or band-stop properties.Compared to Passive FSS,reconfigurable FSS has the advantages when it is used in complicated electromagnetic environment.And it is the research hotspot in areas such as aircraft stealth,satellite communications and electromagnetic compatibility of advanced equipment.This paper focuses on this hot research topic,and carries out a range study on reconfigurable frequency selective surface based on the traditional passive frequency selective surface.Firstly,the physical realization of filtering mechanisms of frequency selective surfaces is discussed in this paper.The filter characteristics and the equivalent circuit model of one-dimensional structure and typical band-pass and band–stop frequency selective surfaces are analyzed.The equivalent circuit modeling and filtering mechanism of the frequency selective surface with multilayer structure are studied by analyzing the frequency selective surface which used multi-layer ring structure and multi-layer patch structureTwo non-reconfigurable frequency selection surfaces were designed and simulated by multi-layer structure.Contains a two-band frequency selection surface with hexagonal ring structure and A band-pass FSS with double transmission zero point using AFA(antenna-filter-antenna)structure,The equivalent circuit model of these two structures is given,and the filtering mechanism is studied by the correlation parameter analysis.The frequency selection surface using hexagonal ring structure operates in the X-band and Ka-band,It's passband-3d B bandwidth is 4.4GHz(8-12.4GHz)and 6.4GHz(26.8-33.2GHz),Relative bandwidth is 43.8% and 21.3%,respectively,it can still maintain a good filter characteristics when the incident wave angle is 60.The passband-3d B bandwidth of the frequency selective surface which using the AFA structure is 0.74 GHz(5.76-6.5 GHz)and the relative bandwidth is 12.1%.The low transmission zero point is genetated at 5.3GHz,while the high transmission zero is 7.05 GHz.The filtering properties of the multilayer structure frequency selective surface and the equivalent circuit analysis laid the foundation for the study of the reconfigurable frequency selection surface.The PIN diodes and varactor diodes are used in the typical bandpass FSS model.Based on the impedance characteristics of PIN diodes,a reconfigurable FSS model with passband switching characteristics is established.The design of the metallized vias is chosen to fuse the FSS filter structure and the feeder line,which effectively reduces the influence of the feeder on the FSS transmission characteristics.The reconfigurable FSS has the characteristics of the passband switch at 3.5GHz.Using the passband switch FSS structure for deformation,A tunable reconfigurable FSS model was established by using varactor instead of PIN diodes.When the capacitance of the varactor is changed from 0.1p F to 1p F,the resonant frequency of the passband moves from 4.06 GHz to 2.59 GHz,and the passband adjustment range is 1.47 GHz.