Planar Dual-Band Circular Polarization Monopole Antenna for Wireless Local Area Networks

A novel planar dual-band circular polarization (CP) monopole antenna is proposed. By introducing an inverted L-shaped strip-sleeve shorted to the ground plane, the proposed dual-band CP antenna design easily achieves impedance bandwidths (RL ≥10 dB) approximating 1932/339 MHz and 3-dB axial-ratio bandwidths approximating 250/360 MHz in 2.4/5.2-GHz wireless local area networks (WLANs), respectively. Across all bandwidths, the measured peak gain and radiation efficiency approximate 2.4/2.8 dBic and 97%/65% in 2.4/5.2-GHz WLANs, respectively, with highly bidirectional patterns in the xz- and yz-planes.