Dual-Band and Dual-Sense Omnidirectional Circularly Polarized Antenna

A circularly polarized (CP) dielectric resonator antenna (DRA) loaded with a modified circular patch is proposed for dual-band applications. The antenna is centrally fed by a probe, giving omnidirectional patterns with different senses of circular polarization in two bands. It is observed that the lower and upper bands are controlled by the patch and dielectric resonator (DR), respectively, making design of the dual-band antenna very easy. For demonstration, a prototype has been designed, fabricated, and measured. The antenna features 10-dB impedance bandwidths of 2.64% and 18.03% and 3-dB axial-ratio (AR) bandwidths of 3.16% and 5.06% in lower and upper frequency bands, respectively.