Use of the dielectric resonator antenna as a filter element

For the first time, the dielectric resonator antenna (DRA) is simultaneously used as a filtering device, named as the DRA filter (DRAF). The theory and design methodology of the DRAF are elucidated using the cylindrical DR. It was found that the operating frequency of the filter part can be made equal to, or different from, that of the antenna part. The return loss, input impedance, radiation patterns, and insertion loss of the DRAF are studied. To improve the insertion loss of the filter part, the DR is top-loaded by a metallic disk without significantly affecting the radiation efficiency of the antenna part. The disk, in addition, can be used to tune the frequency of the filter. It was found that the antenna and filter parts of the DRAF can be designed and tuned almost independently. A second-order DRAF is also designed in this paper. As the dual function DRAF is compact and cost effective, it should find applications in modern wireless communication systems.