Wideband circularly polarised antenna on slot-loaded ground plane

A wideband circularly polarised antenna is presented. It features an inverted L-shaped monopole, an inverted U-shaped strip and a slot-loaded ground plane. The ground plane and U-shaped strip share the same layer, and the L-shaped strip is printed in the opposite layer. The U-shaped strip is useful in increasing the return-loss bandwidth, and the slot on the ground is found crucial to widen the axial-ratio bandwidth. With a proper length of the slot, the experimental results show that the antenna has a return-loss bandwidth of 2.0 GHz (2.05-4.05 GHz) and an axial-ratio bandwidth of 1.8 GHz (2.0-3.8 GHz).