DESIGN OF CPW-FED DUAL-BAND CIRCULARLY-POLARIZED ANNULAR SLOT ANTENNA WITH TWO PERTURBATION STRIPS

A new CPW-fed dual-band circularly-polarized(CP) annular slot antenna with two perturbation strips is proposed. The structure of the annular slot, along with two concentric annularring patches, can achieve dual-band input impedance matching. And circular polarization at the operation bands can be achieved by using the two perturbation strips placed on the backside of the antenna. To reduce the resonant frequencies, a third strip protruded from the ground plane is introduced. Both the simulated and measured results show that the impedance bandwidths determined by 10-dB return loss are about 29.1% for the lower band (1.92-2.61 GHz) and 12.1% for the upper band (3.21-3.65 GHz). And the AR bandwidths are about 7.5% and 11.0%, respectively.