Reconfigurable Axial Ratio in Compact GNSS Antennas

A new adaptive technique for steering the direction of minimum axial ratio (AR) (<;1 dB) toward the reflected or jamming signal is proposed for global navigation satellite systems antennas. It relies on simple, low cost commercially available circularly polarized antenna elements without influencing their gain. Its performance is demonstrated using two different antenna geometries, with five different configurations. The measurements agree well with simulation and theoretical calculations. The technique allows a combined 1-dB AR beamwidth of up to 83°.