Dielectric Resonator Antennas (DRAs) have been shown to be superior to patch
antennas at microwave frequencies (Mongia and Bhartia, 1994; and Lai, 2008). Isolated
Dielectric Resonators (DRs) produce well-defined far-field patterns of different shapes
and properties (Mongia and Bhartia, 1994). However, when coupled to an external
source, the purity of the excited modes deviates from those of the isolated case, which
in turn adversely affects the purity of the far-field pattern. This is mainly because of
the strong field perturbation caused by the particular coupling structure. The mode
distortion is revealed in the form of an increase in pattern asymmetry, crosspolarization
level, null-level or/and side-lobe level. This concern has been raised by
Kishk et al. (1993); and Kishk and Glisson (2001). Differential-feed (Petosa et al., 1999;
and Singh and Sharma, 2010) has been suggested as the most effective method to
prevent mode distortions. Alternative methods of combining single-ended feed with
parasitic elements have also been suggested (Guha et al., 2015a and 2015b). In the
present paper, a method to purify the co-polarized patterns of the HEM21-like HOM
of a CDRA has been proposed and two different implementations of the same have
been validated using Ansoft HFSS simulations.
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