Improved CAD model to compute the resonant frequency of tunable circular patch antenna

For computing the resonant frequency of circular patch antenna with and without variable air gap in between substrate and ground plane an improved and simple CAD model based on cavity model analysis is proposed in this paper. The proposed model is valid for vary large to very small value of patch diameter with entire range of permittivity and thickness of the substrate with variable air gaps. The computed values for different modes with and without variable air gaps and antenna parameters are compared with different theories and experimental values available in open literature. The present model shows very close agreement with the previously reported experiment compared to the other theoretical models.