Circularly polarized dielectric resonator antenna excited by a shorted annular slot with a backing cavity

Excitation of the circularly polarized dielectric resonator antenna (DRA) using a shorted annular slot is studied in this paper. The new method is demonstrated using a hemispherical DRA. The exact DRA Green´s function is used in the formulation, and the method of moments is employed to solve for the equivalent magnetic current in the slot. The input impedance, axial ratio, and field patterns are found. Measurements were carried out to verify the calculations, with good results. The effects of the radius and shorting width of the slot are investigated, and the design procedure of the CP DRA is discussed.