A generalized expression for resonant frequency of circular microstrip antennas

A generalized expression for calculating the resonant frequency of microstrip antennas is presented. The analysis includes the correction factor for higher order modes to obtain the generalized expression for the resonant frequency in the cavity model analysis. Multilayer dielectric circular patch antennas with and without airgap are analyzed using effective quasi-static capacitance approach and compared with the experimental results to show the versatility of the proposed generalization in achieving near to accurate result with more than four fold accuracy as compared to the dominant mode expression