Compact and Tunable Circular Microstrip Patch using Post-Varactor Loading

In this communication we present a novel configuration of varactor diode loaded circular microstrip patch antenna. The diode is connected between the upper patch and the ground plane via a thin inductive post. This results in reduction of resonant frequencies for all the modes of a circular patch radiator. This radiator is also widely tunable with the changing bias of varactor diode. The theoretical justification is also presented and the computed results are compared with experimental results.