Compact broad-band annular ring antenna for global navigation satellite systems

A compact circularly polarized annular ring antenna is proposed for global navigation satellite systems (GNSS). The antenna is excited by two L-probes connected to the 90± power divider printed on the back. The high impedance of the annular ring working at TM₁₁ mode is transformed to low values by the L-probes. The antenna has a 44.2% 10-dB return loss bandwidth and a 37.8% 3-dB axial ratio bandwidth, respectively, due to the L-probes and the power divider. The gain bandwidth of the antenna is sufficiently enough to cover the bands of COMPASS, Galileo, GPS and GLONASS systems around 1.575 GHz.