A novel dual-loop ground-radiation antenna for circularly polarized GNSS applications

In this investigation, a circularly polarized (CP) dual-loop ground-radiation antenna has been proposed for GPS applications using a transverse loop and a longitudinal loop. The transverse loop is designed within an 8 mm x 4.5 mm (0.042 lambda x 0.024 lambda) clearance, installed at the horizontal edge of the ground plane for excitation of the ground mode along the y-axis, whereas a 1 mm x 10 mm (0.005 lambda x 0.053 lambda) longitudinal loop is etched at the vertical edge of the ground plane for excitation of the ground mode along the x-axis. In this way, the magnitudes and phases of the orthogonal components of the radiated electric field have been controlled independently, satisfying the CP conditions. The proposed antenna produced right-hand circular polarization towards the + z-axis, which has been verified using rectangular and square-shaped ground planes. Both simulation and measurement were conducted, and the measured axial ratio bandwidth with reference to 3 dB was 20 MHz (1.27%) while the impedance bandwidth with reference to -6 dB was 141 MHz (8.95%).