Polarization Re-configurable Antenna Using SPDT Switch with Off-Centered Fed

Abstract

This letter proposed a novel circular polarization (CP) reconfigurable antenna with off-centered fed. The off-centered feed line is designed to separate two orthogonal modes produced by the antenna with 90 degree phase difference, which could form a circular polarization wave. By controlling the state of a single-pole double-throw (SPDT) switch, different RF paths can be chose and the antenna can work in left-hand circular polarization (LHCP) mode or right-hand circular polarization (RHCP) mode with the 3-dB axial ratio (AR) bandwidth of 16.3%.When the SPDT is left turn-on, the antenna in the direction of Z axis works in LHCP and in negative direction of Z axis works in RHCP. The switch is directly driven by digital signal and no bias network is needed. The measured results are agreed well with the simulations. This proposed antenna is suitable for WLAN 5.2 GHz/5.8 GHz applications.