A dielectric resonator on a microstrip antenna

As long as the resonant frequency of a stand-alone parasitic element is close to but not equal to that of the active microstrip antenna, mutual coupling effects between them could alter the characteristics of the entire system. Satisfactory results are observed when the passive element is placed on top of the patch antenna. For best results, the size of the passive element must be approximately equal to that of the active patch. Thus, it is not convenient to alter the characteristics of a given microstrip antenna. To this end, a much simpler technique is contemplated: to replace the bulky passive microstrip antenna by a small dielectric resonator of similar resonant characteristics. The characteristics of the dielectric resonator loaded microstrip antenna are measured by an HP8510 network analyzer. Variation of the resonant frequency of the loaded antenna with respect to the distance between centers of the patch and disk is shown. As expected, the resonant frequency is practically identical to that of a stand-alone microstrip antenna as long as the dielectric disk is placed inside the circular patch.<>