Circularly-polarized conical-beam patch antenna with wide bandwidth and polarization diversity

This paper introduces a wideband circularly polarized (CP) antenna with polarization diversity for conical-beam radiation pattern. The antenna composes of a wideband monopolar patch and eight parasitic loop stubs. Shorting pins on the monopolar patch are used to obtain a wide impedance bandwidth. And the other set of shorting pins on the loop stubs are utilized for realizing a wide axial ratio bandwidth. PIN diodes are applied to achieve polarization diversity. Right handed circular polarization (RHCP) and left handed circular polarization (LHCP) can be altered by controlling the operation of different group of diodes. Obtained results show that the proposed antenna has the wide impedance bandwidth of 29% and the wide axial ratio bandwidth of 15% for both CP modes. In addition, the stable conical-beam radiation patterns can be found across the operating bandwidth with the maximum gain of 4.4 dBic. This antenna is suitable to be mounted on moving vehicles for geostationary satellite communication without satellite tracking.