Circular patch antenna with nearly-equal E- and H-plane co-polarization patterns

Circular patch is one of the few basic geometries of microstrip patch antennas, and have been studied extensively in the literature [1, 2]. Typically, a substrate material is used between the patch and the ground plane to give the mechanical support to the antenna. The performance of microtrip antennas is strongly dependent on the properties of the substrate material used. Sine electromagnetic wave is trapped inside the dielectric material, the radiation patterns of the microstrip antenna are affected by the substrate. It has been observed that for a certain value or range of the substrate permittivity, the co-polarization patterns of Eand H-planes of the circular patch antenna, for the dominant and several higher order modes, become nearly equal to each other at least in a particular range of elevation angle. This paper discusses this interesting phenomenon using commercial electromagnetic (EM) software: Ansoft Designer, version 4.