Wideband circularly-polarized conical beam wheel-shaped antenna with reflector for axial ratio bandwdith and pattern improvement

Wideband circularly-polarized (CP) conical beam wheel-shaped antenna with a back reflector is presented in this paper. The wheel-shaped antenna composes of a center-fed monopolar patch which generates a vertically polarized electric field E_θ and eight coupling loops which radiate a horizontally polarized electric field E_φ. Both fields have conical-shaped patterns and circular polarization is obtained when their phase difference reaches 90°. By adding the back reflector, the axial ratio (AR) of the proposed antenna is widen to 25% (for AR <; 3dB). An antenna prototype operating at C band is fabricated and tested to verify the simulation. Measured results show that the proposed antenna exhibits wide impedance bandwidth from 4.88 GHz to 6.5 GHz (28%) and AR bandwidth from 4.7 GHz to 6.05 GHz (25%). In addition, conical beam radiation pattern is observed and front to back ratio is improved largely with present of reflector.