Wideband Omnidirectional Circularly Polarized Antenna Based on Tilted Dipoles

A wideband omnidirectional circularly polarized (CP) antenna is developed. The omnidirectional CP antenna includes four tilted dipoles that are wrapped around a cylinder for omnidirectional CP pattern. Each tilted dipole is coupled with a parasitic element for bandwidth enhancement. It is shown that the wideband omnidirectional CP antenna achieves an axial ratio (AR) bandwidth of 44% (1.69-2.64 GHz) for AR <; 3 dB and an impedance bandwidth of 61% (1.35-2.54 GHz) for return loss >10 dB. The antenna gain is around 1 dBi with an omnidirectionality of less than 1.5 dB.