DOUBLE SCREEN FSSs WITH MULTI-RESONANT ELEMENTS FOR MULTIBAND, BROADBAND APPLICATIONS

Design investigations are presented for double screen frequency selective surfaces (DSFSSs) with multi-resonant elements. The DSFSS is composed of two identical single layer frequency selective surfaces (FSSs) separated by a foam layer. By tuning the thickness of the foam, a four-band FSS with improved S-band performance and a dual-band band-stop FSS with broad bandwidths and rapid rolloffs are designed. Both designs are angle and polarization insensitive. The Fabry-Perot interferometer (FPI) theory demonstrates that DSFSSs with a large distance between the metallic arrays are not suitable for broadband band-stop applications due to the interruptions of undesired transmission peaks, which are the results of array interference. An equivalent circuit model is developed to give an insight into the response of the DSFSS. Experimental veri. cations are carried out. The calculated results agree well with the measured ones.