A Dual-Band Dual-Sense Circularly Polarized Slot Antenna with Cascaded Nonradiative Resonator

A practical technique for creating dual-band dual-sense circular polarization is presented in this letter. On the ground plane, two identical slot radiators are etched out orthogonally and cascaded with a nonradiative resonator. Three coupled resonators produce three linearly polarized modes, resulting in dual-band dual-sense circularly polarized radiation. The operating mechanism is preliminarily investigated using the characteristic mode analysis. Furthermore, a quantitative design method based on an equivalent circuit model is proposed, which can predict the theoretical axial ratio (AR) response. To validate the proposed design method, an antenna prototype is fabricated and measured. Left-handed circular polarization and right-handed circular polarization are obtained in the low band and the high band, respectively. The measured impedance bandwidths in two operating bands are 35.48% and 25%, respectively, corresponding to 3 dB AR bandwidths of 7.1% [(2.31 to 2.48) GHz] and 5.06% [(3.08 to 3.24) GHz]. © 2002-2011 IEEE.