Implementation of Parasitic DRA Elements for Improvement of Circular Polarization

In this letter, for the first time, the sequential rotation technique is implemented by applying four parasitic dielectric resonator elements to achieve a noticeable improvement of circular polarization (CP) purity. Specifically, the parasitic elements cancel the cross-pol E-field component, and then, the improvement of CP performance is achieved. In the proposed structure, the main element is only excited, and parasitic elements have no aperture coupling and feed network system. Therefore, it leads to reduced feed complexity and ohmic loss in millimeter-wave (MMW) frequency. The measured low axial ratio bandwidth (
$< $
1.5 dB) is 12.42%. Furthermore, to design the single-element antenna, a toothed dielectric resonator antenna (DRA) configuration is presented, which not only provides more orthogonal modes but also enhances the CP gain at each resonant frequency. The measured maximum CP gain is 8.33 dBic for a single-element DRA.