Circularly Polarized Reconfigurable Patch Antenna with an Annular Slot on the Ground

An annular slot coupled reconfigurable patch antenna with circular polarization (CP) is proposed. By loading two controllable PIN switches and three capacitors across the annular slot, a square radiating patch can be switched between the left-hand CP (LHCP) and right-hand CP (RHCP). The simulated -10dB impedance bandwidth of proposed antenna is 15.4% with 3-dB axial ratio (AR) bandwidths of 3.7%; broadside radiation patterns were observed in both LHCP and RHCP with maximum gains of 8.9 dBic. The proposed design exhibits simple DC bias that can be easily extended to array applications.