Compact antenna design with bandwidth enhancement

A novel wideband compact antenna design at the edge of the ground plane is presented. The design, mainly composed of an edge-coupled capacitor as a tuning mechanism, can be used as building blocks for future multi-band antennas with reconfigurable operation in which the capacitor is replaced by a varactor. The antenna is first designed with an inductive feed. The corresponding equivalent circuit is also presented, in which the contribution of each parts of the antenna are explained. The antenna can be miniaturized by tuning the edge-coupled capacitor and the inductive effect between the antenna structure and the ground plane. The capacitive feed mechanism is later introduced to replace the original inductive feed. With the capacitive feed, the impedance bandwidth of the antenna can be significantly enhanced from 9% (2.15-2.41 GHz) to 49.6% (1.695-2.763 GHz), while the size of the antenna is 10×11 mm².