Scattering from finite extent frequency selective surfaces illuminated by arbitrary sources

It is shown through a series of theoretical calculations that frequency-selective surfaces (FSSs) of an array of metallic patches on dielectric films may have applications as diplexers in multifrequency reflector antennas, since they create spatially separated images of the focal region at different frequencies. A formula is developed for calculating the primary pattern of the feed and dichroic plate assembly of a typical array of FSSs, based on the theorem of reciprocity. A diagram of the transmitted and reflected primary patterns is given.