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 E
_θ
and E
_φ
components are obtained from the TM
_01δ
mode of the DR and the slotted ground plane, respectively. Omnidirectional CP fields can be obtained when E
_θ
and E
_φ
are 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.