A novel loop-like monopole antenna with dual-band circular polarization (CP) for the reception of WiMAX and WLAN is designed and implemented in this paper. The antenna consists of a radiating patch which is composed of an annular-ring linked by a square ring over the corner and a ground plane with embedded rectangular slit. The broad impedance bandwidth is achieved based on a novel monopole structure which is the combination of two perturbed loops and the perturbation causes the generation of right-hand circular polarization (RHCP) at 3.52 GHz and left-hand circular polarization (LHCP) at 5.75 GHz. In addition, by embedding a rectangular slit on the ground, the impedance bandwidth can be greatly enhanced. The measured results show that the proposed monopole antenna has an impedance bandwidth of 3.65 GHz from 2.65 to 6.3 GHz, reaching the particularly broad bandwidth of 81.6%. Furthermore, the measured 3-dB axial ratio (AR) bandwidths are about 440 MHz at the lower band (3.52 GHz) and 220 MHz at the upper band (5.75 GHz). The radiation characteristics of the implemented antenna are also presented.
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