Omnidirectional Circularly Polarized Dielectric Resonator Antenna With Logarithmic Spiral Slots in the Ground

A new omnidirectional circularly polarized (CP) cylindrical dielectric resonator (DR) antenna (DRA) is excited by four open-ended logarithmic spiral slots in the ground plane. Radiated Eθand Eφcomponents are obtained from the TM01δmode of the DR and the slotted ground plane, respectively. Omnidirectional CP fields can be obtained when Eθand Eφare equal in magnitude but different in phase by 90°. This CP technique does not require any special shape or treatment of DR, greatly facilitating the design. To demonstrate the idea, a prototype using a glass DR was fabricated. It is a dual-function DRA that also serves as the cover of light sources. The prototype has a measured bandwidth of ~6.2%, covering the entire 2.4-GHz WLAN band.