This paper presents a novel dual-band circularly polarized CPW-fed circular slot antenna with two open-ground rings. The proposed antenna is constructed with two opened-ground rings facing in opposite directions and embedded in the circular slot, and the enhanced feed strip of CPW. By way of adjusting the relevant parameters, we can obtain the dual-band at 1.57 GHz and 2.46 GHz respectively. A smaller frequency ratio of 1.56 is presented. The measured -10 dB return loss impedance bandwidth are 380 MHz (24.68%) for 1.57 GHz band and 210 MHz (8.33%) for 2.46 GHz band. The measured -3 dB axial ratio bandwidth for 1.57 GHz and 2.46 GHz bands are 13.38% and 8.13%, the polarization of radiation patterns are RHCP and LHCP for each band and the antenna gain are 3.72 and 3.21 dBic respectively.
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