Design of broadband circularly-polarized monopole antenna for wirless communication

A broadband monopole antenna for circularly-polarized (CP) applications is proposed. The broadband property of the antenna is basically achieved not only by the chifre-shaped monople radiator but also its asymmetric microstrip feedline. The CP characteristics is enhanced significantly by adjusting the lacation of the monople feed. The antenna delivers wideband performance in terms of impedance matching and circular polarisation. The measured results agree with the simulaitons reasonablly, and the measurements demonstrate an impedance bandwidth of 72% for the reflection coefficient no more than -10dB and a 3-dB axial-ratio (AR) bandwidth of 41.6% with the central frequency of 2.5 GHz.