Active frequency-selective surfaces

Abstract
Two different varieties of active frequency-selective surfaces (FSS) are described. In one type, active FSS elements incorporating switched PIN diodes are discussed. Waveguide simulation studies show that the frequency response of the surface can be electronically switched from that of a reflecting structure to a transmitting structure. In the other type, FSS are printed on ferrite substrates which are biased with a DC magnetic field. The application of this bias field to the ferrite allows tuning of the resonant frequency by several gigahertz. In addition, the frequency characteristics can be switched from transmitting to reflecting, as for the active element FSS.