Characterization of microstrip patch antennas suspended by a dielectric superstrate with high permittivity

The impedance and radiation characteristics of a coaxially-fed microstrip patch antenna suspended by a dielectric superstrate with high permittivity are extensively studied based on the spectral-domain moment method. As for the case of a dielectric superstrate (/spl epsiv//sub r/=10.5) with 7 types of thicknesses, the complicated variation of its characteristic such as the resonant frequency, the excitation efficiency of radiation fields and surface-wave fields, the input impedance and the radiation pattern, with intervals of the air-layer, are theoretically demonstrated, while some fundamental experiments on the resonant frequency and the return loss are performed to confirm the predicted results.