Theoretical Investigation of Resonant Modes of Shorting Post Loaded Circular Microstrip Antenna On Sphere

Abstract

In the present work the resonance properties of TM₀₁ and TM₁₁ modes of a spherical-circular patch antenna are investigated when loaded with single shorting post. The cavity model is used to predict the frequencies of the resonant modes. It is shown that angle of curvature has a significant effect on the tunability of the resonant modes. Beyond a critical angle of curvature the resonant frequency of the post loaded disk on sphere decreases with increasing radial distance of post from the centre of the patch. This is in complete reversal to the trend displayed by a planar circular disk antenna loaded with shorting post. Also demonstrated is the fact that asymmetric post loading leads to generation of three split resonances. Preliminary experiments conducted on such shorted patch antennas, corroborates the theory.