Bandwidth Enhancement of a Polarization-Reconfigurable Patch Antenna With Stair-Slots on the Ground

A polarization-reconfigurable rectangular patch antenna for bandwidth enhancement is proposed. This antenna has stair-slots on the ground and two p-i-n diodes are used for switching the antenna's polarization in linear polarization (LP), left-hand circular polarization (LHCP) and right-hand circular polarization (RHCP). The structure is concise and easy to optimize, and dc bias network is very simple. The measured impedance (-10-db S11) and 3-dB axial-ratio (AR) bandwidths are about 180 and 37 MHz, respectively, at the center frequency around 2.46 GHz for both LHCP and RHCP. Compared to the reference antennas (antenna with loop slots on the ground and antenna with L-shaped slots on the ground), the bandwidths of -10-dB S11 and 3-dB AR are greatly enhanced. The asymmetrical slotted ground excites TM10 and TM01 modes with different resonant frequency to generate CP radiation, and because of the stair-slots, instead of loop slots and L-shaped slots, the lower resonant frequency decreases and the higher one increases. Thus, the bandwidths are improved. The antenna has good switchable and radiation performances. It could be used for wireless local area network (WLAN) (2.4-2.5 GHz) in wireless communication systems.