A Low-Profile Wideband Omnidirectional Antenna with Reconfigurable Tri-Polarization Diversity

This paper presents a low-profile wideband omnidirectional antenna with reconfigurable tri-polarization. The proposed antenna is composed of a center-fed circular patch part that generates vertically polarized electromagnetic (EM) waves and a bent-branch connected patch part at the bottom that generates horizontally polarized EM waves. By loading PIN diodes on the symmetrical curved branches, the directions of the current flows on the antenna can be controlled to achieve reconfiguration between left-hand circular polarization (LHCP), right-hand circular polarization (RHCP) and linear polarization (LP). Measurement results show that the overlap bandwidths of -10-dB impedance and 3-dB axial ratio (AR) of the antenna are 10.87% (2.35-2.62 GHz) and 10.91% (2.34-2.61 GHz) for LHCP and RHCP modes, respectively. Under the LP mode, the -10-dB impedance bandwidth is 13.44% (2.29-2.62 GHz). The peak gains of the antenna are 4.8 dBic, 4.7 dBic, and 4.9 dBi for the LHCP, RHCP, and LP modes, respectively. Measurement results agree well with the simulation results, verifying the effectiveness of the antenna.