AR bandwidth enhancement for single-feed circularly polarized square ring slot patch antenna

Novel configurations to enhance the Axial Ratio bandwidth of single-feed square ring slot patch antennas are proposed. Some slot perturbations and cuts along the patch border, as well as adding a parasitic patch, allow us to achieve 3dB AR fractional bandwidth up to 12%. Performance results are shown for a 3.5GHz WiMAX™ antenna.