Investigation of dual mode wideband rectangular and cylindrical dielectric resonator antennas

The dielectric resonator antenna (DRA) is quite useful for high frequency applications where ohmic losses become a serious problem for conventional metallic antennas. In addition, they offer higher bandwidths than microstrip patch antennas used in the same frequency range. There are many techniques for increasing the bandwidth of DRAs and many of them increase the complexity of the structure. The paper is concerned with the excitation of two modes with similar radiation characteristics in the same DRA. By adjusting the ratio of the diameter to the height, the modes can be made to resonate close to each other and the bandwidth is thereby increased. The characteristics of the cylindrical DRA and the rectangular DRA are compared. The results show that, by exciting two simultaneous modes, the bandwidth of a DRA can be increased without extensively modifying the geometry.