Wideband polarization reconfigurable circularly polarized antenna with omnidirectional radiation pattern

This paper presents a wideband reconfigurable circularly polarized (CP) antenna with omnidirectional radiation pattern. The antenna is based on a shorted monopolar patch surrounded by multiple curved branches and it is proximity-fed by a disk-loaded coaxial cable. The polarization reconfigurability is realized by introducing PIN diodes on junctions between the patch and the branches to alter the current direction flowing on the branches. By properly controlling the ON/OFF states of the diodes, the antenna's polarization can be switched between right-hand circular polarization (RHCP) and left-hand circular polarization (LHCP). A reconfigurable prototype has been fabricated and measured. The experiments show that the prototype has wide overlapped bandwidth from 2.3 to 3.1 GHz, in which the reflection coefficient and the axial ratio (AR) are less than −10 dB and 3 dB for both polarization states. Besides, the antenna radiates dipole-like patterns with the realized gain of around 0.6 dBic across this operating band.