A polarization reconfigurable microstrip patch antenna using PIN diodes

A microstrip patch antenna with reconfigurable polarization states among right-hand circular polarization (RHCP), left-hand circular polarization (LHCP) and two linear polarizations (LP) is proposed. The proposed antenna has stacked structure consists of a radiator with a ring-slot and a cross slot, four PIN diodes and a single feed line. The polarization state can be determined by switching the PIN diodes ON and OFF. To improve the impedance matching characteristic, the cross slot is used. The proposed antenna has 40 MHz 10 dB return loss bandwidth and more than 8 MHz 3 dB axial ratio bandwidth in the circularly polarized state.