The Study Of Frequency Selective Surface Base On EM Coupling

Frequency selective surfaces(FSSs)can be viewed as spatial filters,which are generally realized using a planar periodic structure.The response of the FSS is also related with the incident angle and polarization.FSS has been widely used in radomes,transmitarrays,reflectarrays and radar stealth.In this paper,the FSS structure based on electromagnetic coupling structure is studied.In order to improve performance of FSS,electromagnetic coupling is introduced in the FSS.Firstly,a FSS element based on slot-coupled metallic-strip resonator was studied miniaturized.To investigate the operating principle of the slot-coupled FSS,an equivalent-circuit model was constructed according to the physical structure and analyzed using the odd-/ even-mode method.Coupling coefficient was also extracted.The influence of the physical dimension on the performance and the angular stability was simulated by the full-wave EM simulation.A high-selectivity bandpass FSS with two transmission zeros was finally designed.Based on the above-mentioned slot-coupled FSS,several design methods of dual-band FSS topology were proposed.One of these topology methods was thoroughly analyzed and a topological structure with good isolation between the two passbands was designed on this basis.An ultra-thin compact dual-band FSS was designed.We have also improved the traditional structure of the upper and lower layer location of the non-resonant FSS element to enhance the coupling between the upper and lower layers.The fractional bandwidth of a broadband FSS with five layers of metal structure achieved 37%.