Foo, Senglee (Powerwave Technologies, 1801 E St. Andrew Place, Santa Ana, California, USA, 92705)
A superstrate together with its antenna ground plane forms a resonance structure, which gives rise to a field distribution that produces a larger effective aperture. The resultant increase in the overall directivity of a single patch can be quite significant depending on sizes of the superstrate and the antenna ground plane. A superstrate can be constructed in several ways, including use of multiple layers of dielectric materials with high dielectric constants, layers of EBG FSS structures, and use of parasitic patches. This paper studies a few possible superstrate structures and compares their performances, such as bandwidth and effect on polarization. Of particular interest is the effect of superstrates on multi-column arrays for multibeam applications.