ABSTRACT
The experimental discovery of unexpectedly high levels of transmission of light through perforated metal screens initiated a period of notable interest on the problem of transmission of electromagnetic waves through electrically small holes practiced in opaque slabs. The geometrical similarities between extraordinary transmission structures and aperture-type frequency-selective surfaces (FSS) are rather obvious. FSSs have been used for decades as spatial filters by antenna practitioners and, hence, a lot of research efforts have been devoted to this topic in the past. FSSs are two-dimensional arrays of planar metallic patches periodically distributed on a surface. The important point is that accurate and physically sound models of FSSs have been developed to account for their qualitative behavior and for the design of their transmission features. One may wonder why extraordinary transmission is special when compared with ordinary transmission observed in FSSs. Aperture-based FSSs are band-pass filters where total transmission is possible around the resonance frequency of the patterned holes.
