Switchable Frequency Selective Slot Arrays

A switchable frequency selective surface (FSS) made of square loop slots and PIN diodes connected to a novel separate biasing circuit is presented. The structure uses a very thin, flexible substrate sandwiched between two physically independent metallic layers to create the active filter. An application is the modification of the EM architecture of buildings, where propagation could be controlled using active FSS. The relatively small number of elements employed creates a compact FSS structure which could fit in an aperture within a wall of a building. The Fabry-Perot approach is used to design a cascaded version for improved filter selectivity.