Theoretical investigation of resonant modes of shorting post loaded circular microstrip antenna on sphere

In the present work the resonance properties of TM01 and TM11 modes of a sp herical-circular patch antenna are investigated when loaded with single sho rting post. The cavity model is used to predict the frequencies of the reso nant 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 in creasing radial distance of post from the centre of the patch. This is in c omplete reversal to the trend displayed by a planar circular disk antenna l oaded with shorting post. Also demonstrated is the fact that asymmetric pos t loading leads to generation of three split resonances. Preliminary experi ments conducted on such shorted patch antennas, corroborates the theory.