Design of Circular Waveguide Annular Slot-Coupled Two-Layer DRA for Linear and Circular Polarizations

The design of a circular-waveguide coupled two-layer dielectric resonator antenna (DRA) configuration is presented. It is observed that besides a reduction in the number of layers compared to a rectangular waveguide coupled multilayer-DRA structure to achieve coupling and enhanced bandwidth, the current configuration significantly enhances the functionality of the design in the realization of dual band and right-hand/left-hand circularly polarized (RHCP/LHCP) configurations without the use of additional coupling or matching elements, which, to the best of our knowledge, has not been reported earlier. Radiation characteristics with low cross-pol are achieved for the linearly polarized dual-band antenna structure. For the circularly polarized configurations, a good axial-ratio performance and a high isolation between the RHCP and LHCP fields are achieved. The computed results are obtained through a full-wave Green's function analysis of the structure, with the thickness of the ground plane modeled as an annular cavity.