Mutual coupling reduction in a multi-mode multi-function dielectric resonator antenna

In a rectangular dielectric resonator, the mutual coupling between TE 111 and Quasi-TM 111 mode is in theory zero due to the orthogonal field distributions. In practice, some coupling is observed in a two ports dielectric resonator antenna (DRA) design based on those two modes. The mutual coupling can be explained by the asymmetric field distribution resulting from asymmetric feeding methods. Through analysis of the field distribution, two different methods are proposed to reduce mutual coupling to less than -15 dB. The first method considers an asymmetric resonator, whereas the second one symmetrizes the feeding. Designs with both methods are presented and their advantages and weaknesses are discussed.