Frequency Tuning of the Linearly and Circularly Polarized Dielectric Resonator Antennas Using Multiple Parasitic Strips

A rigorous analysis of the conformal-strip-excited hemispherical dielectric resonator antenna (DRA) with multiple parasitic strips is presented in this paper. The problem is formulated using the Green's function approach, with the strip currents solved by using the method of moments. It is found that the strips can be used to tune the operating frequency of both the linearly polarized (LP) and circularly polarized (CP) DRAs. In designing the LP DRA, the parasitic strips are placed symmetrically in pairs to minimize cross-polarized radiation fields. For the CP DRA, however, the parasitic strips are asymmetric, with their parameters determined by using the Genetic Algorithm. Measurements were carried out to verify the calculations, and reasonable agreement between theory and experiment is obtained.