The Role of Feed Perturbation in the Design of Microstrip-fed Cylindrical Dielectric Resonator Antennas

Abstract

In this paper, the role of feed perturbation in the design of a cylindrical dielectric resonator antenna (DRA) for maximum modal purity is investigated both numerically and experimentally. Modal purity is indicated by the purity of the far-field radiation which can be quantified by the radiation pattern symmetry and the cross-polarized radiation. To demonstrate the feed perturbation effect, a microstrip line proximity coupled to a cylindrical dielectric resonator exciting its lowest order broadside radiating mode is used. It is identified that the feed perturbation introduces higher order fields of TM01δ and HEM21δ types of the DRA to disturb the modal purity of the desired mode. Results suggest that optimum DRA design should consider the feed perturbation effects also in addition to the common performance parameters such as impedance matching, bandwidth and gain.