In this communication, we first present the superstrate loading effect on a circularly polarized rectangular microstrip antenna. The design parameters of the superstrate-loading microstrip antenna for achieving circular polarization at the main-beam direction are discussed. The circular polarization property in the entire main-beam region is also analyzed. Next, the crosspolarization characteristies of a rectangular patch antenna due to the superstrate loading are studied. A great dependence Of the e’PO1arized and crossPO1arized radiations On the superstrate permittivity and thickness is observed.
