Experimental investigation of multi-element dielectric resonator antennas

Studies of dielectric resonator antennas (DRA) have demonstrated their potential for millimeter wave applications due to their several advantages over microstrip patch antennas such as high radiation efficiency and absence of surface waves. The basic DRA structure consists of a dielectric resonator (DR) placed on a ground plane, coupled by a coaxial probe through the ground plane or a slot cut in the ground plane. Its bandwidth is mainly determined by the permittivity and structural aspect ratio of the DR. To improve the bandwidth, an air gap between the DR and the ground plane can be introduced, or the DR can be coated with a lower-permittivity dielectric layer. Stacked and parasitic coplanar configurations can also be used for bandwidth enhancement. The paper experimentally investigates a DRA that uses two- or three-element rectangular DRs, all coupled by a single slot in the ground plane of a microstrip line, and illustrates the usefulness of this structure for the realization of a wider band or dual-band operation.