A Reconfigurable Circularly-Polarized Microstrip Antenna with Simple Two-Branch Switchable Feed Network

This study proposes a new concept of a microstrip antenna with circular polarization (CP) reconfigurable function. The proposed CP switchable antenna consists of a corner-truncated single patch element and a simple two-branch switchable feed network. Each branch is connected to a PIN diode. CP switching between the left-hand circular polarization (LHCP) and right-hand circular polarization (RHCP) can be achieved by applying positive and negative switching voltage, respectively. In the measurement, the 10-dB impedance bandwidth of 4.3% and 4.4% are achieved for LHCP and RHCP, respectively. The axial ratio is lower than 3 dB, and around 6.5-dBic antenna gain is achieved for both LHCP and RHCP. The proposed concept and performance are evaluated by simulation and measurement.