A novel dual-helix monopole antenna with circular polarization (CP) operation is proposed. By utilizing a pair of asymmetrical strip-sleeves shorted at the ground plane, the proposed CP design at 2.45 GHz ISM band can easily be achieved and provides the impedance bandwidth (RL≧10 dB) about 240 MHz and the 6 dB axial-ratio (AR) bandwidth about 126 MHz. The measured peak gain and radiation efficiency are about 9.1 dBic and 81% across the operating bands, respectively.
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