A novel polarization reconfigurable circularly polarized antenna

A novel polarization reconfigurable circularly polarized (CP) antenna is proposed in this paper. The antenna is composed of a pair of rectangular loops and two parasitic rectangular loops. Four PIN diodes are soldered on the rectangular loops. By changing the states of the PIN diodes, the operation of the rectangular loops can change between the left handed circular polarization (LHCP) and the right handed circular polarization (RHCP). A T-shaped microstrip feed line is introduced to feed the antenna. Experimental results show that the polarization reconfigurable CP antenna achieves an impedance bandwidth of 31% (2.05–2.8GHz) for return loss >10 dB and a CP bandwidth of 16% (2.3–2.7GHz) for axial ratio (AR) <3 dB. The measured gain of the reconfigurable CP antenna is about 5.5 dBi.