A Planar Circular Polarization Reconfigurable Trapezoid Monopole Antenna with Wide Axial-ratio Bandwidth for GNSS

A circular polarization (CP) reconfigurable monopole antenna with wide axial-ratio bandwidth (ARBW) for the Global Navigation Satellite System (GNSS) is presented. The antenna consists of two trapezoid monopoles placed symmetrically, a switchable feed network, and a right-angled isosceles triangular ground plane. The trapezoid monopoles are meandered to make the antenna more compact. The monopole radiator is fed asymmetrically with respect to the ground plane central line to generate CP. The two PIN diodes of the switchable feed network determine which monopole on the left or right side is fed by RF signal, thus generating right/left-handed CP (RHCP or LHCP). These two PIN diodes are controlled by the bias-T, so there is no need to use any additional biasing line. It eliminates the effect of the DC biasing lines on the RF performance. The simulated and measured return loss, axial-ratio, radiation patterns, realized boresight gains, and efficiencies are studied. Measured results show that the antenna can operate from 1.17 to 1.74 GHz (0.57 GHz, 39.2%) in RHCP and from 1.18 to 1.74 GHz (0.56 GHz, 38.4%) in LHCP covering the whole frequency bands of GNSS.