A Wideband Design of Circularly Polarized Antenna With High Gain

A high gain design of the circularly polarized (CP) antenna is proposed to achieve wide axial-ratio (AR) bandwidth. A sequential rotation technique is employed to excite the array of four microstrip patches with dual-offset feeding. Significant improvement in CP gain is achieved by using a strategically designed metallic wall. The AR remains below 1dB over the 52.5% (8.54−14.62 GHz) impedance bandwidth of the antenna, indicating a 52.5% AR bandwidth. Over the entire operating frequency band, the left-handed CP (LHCP) gain remains above 11.2 dBic and reaches 14.84 dBic at 13GHz. The LHCP gain can be enhanced by approximately 4 dB by using the metallic wall. Cross-polar discrimination (XPD) is better than 35dB and can reach up to 54dB. The AR beamwidth is approximately 28° or more and shows the CP coverage around the boresight direction.