Analytical treatment of microstrip monopole antenna with finite ground plane

The effect of finite ground plane on resonant frequency of microstrip monopole antenna is studied. Electric field corresponding to a microstrip monopole antenna follows an elliptic path between the monopole and the finite ground plane, and is analogous to TE_c01 mode of an elliptic waveguide with PMC walls. The authors have used this elliptic waveguide model to understand the effect of size of the finite ground plane on resonant frequency. A prototype of microstrip monopole antenna resonating at 2.03 GHz on a substrate having ε_r = 4.3 is fabricated. Good agreement between the theoretical and the measured results showed the validity of the proposed cavity model and the related analysis.