Dual Frequency Circularly Polarized Microstrip Antenna

Design and analysis of a single-feed arrangement of rectangular patches is proposed, which is capable o f providing dual frequency circular polarization along with broadband performance. An antenna is designed on a glass epox y FR-4 substrate with overall thickness of the structure l ess than 8 mm or 0.11A 0. Axial ratio bandwidth better than 1.04 % and impedance bandwidth better than 10.89% may be achieved with the proposed geometry. Measured gain and axial ratio variations of the proposed antenna with frequency are compared to simulated results for better understanding. The measured E- and H-plane radiation patterns in the entire impedance bandwidth are identical in shape, and the direction of maximum radiations is normal to the patch geometry. In the entire axial ratio bandwidth range of the proposed antenna, the E-plane left circularly polarized patterns are nearl y 15 dB.