Wideband polarization converters based on miniaturized-element frequency selective surfaces

Polarization of a wave is an important aspect of its propagation characteristics. In antenna design, the choice of the polarization mostly depends on the application and also the propagation environment. For instance, in satellite communications or navigation systems, circularly-polarized waves are preferred due to advantages such as lower sensitivity to multipath fading. Over the past decades, several designs of antennas have been reported that radiate circularly-polarized waves. An alternative way of generating such waves is to generate waves with linear polarization and pass them through a polarization converter. Polarization converters are anisotropic media that convert linearly-polarized incoming waves to circularly-polarized waves at their output apertures. Traditionally, frequency selective surfaces with resonant elements have been employed to design such converters. The drawback associated with most of these structures, however, is their narrow bandwidths (due to the resonant nature of their element) as well as the deterioration of their phase response under oblique incidences.