Axial Ratio and Impedance Bandwidth Enhancement of a Circularly Polarized Dielectric Resonator Antenna Using Defected Ground Structure

This article presents a novel circularly polarized stacked dielectric resonator antenna (DRA) featuring etched slots arranged in an L-pattern within the ground plane. An analysis of the current distribution on the ground plane reveals that the inclusion of these slots results in the formation of two distinct current paths. This, in turn, leads to measured resonances: one at 6.3 GHz corresponding to the fundamental T E 11 delta z $T{E}_{11\delta }<^>{z}$ mode, and another at 7.8 GHz corresponding to a higher order mode, T E 23 delta z $T{E}_{23\delta }<^>{z}$. The DRA is a stacked antenna composed of two discs made of a material with epsilon r ${\varepsilon }_{r}$ = 9.8, separated by an air gap. The upper disc is perforated with three holes, strategically reducing the effective dielectric constant and thereby yielding a substantial high-impedance bandwidth spanning from 6 to 9 GHz. This innovative design boasts simplicity in fabrication while delivering impressive performance metrics. Specifically, it achieves a noteworthy 39.6% impedance bandwidth and a 38% 3 dB axial ratio (AR) bandwidth, with overlapping coverage ranging from 6 to 8.5 GHz. Consequently, this antenna stands as an excellent choice for 5G applications operating in frequency ranges beyond the sub-6 GHz band. The measured gains for this antenna are 5.52 dBi at the resonant frequency of 6.3 GHz and 4.5 dBi at 7.8 GHz. These gains are consistently maintained above 4 dBi throughout the entirety of the 39.6% impedance bandwidth. Furthermore, the efficiency of the antenna remains consistently above 90%.