Frequency-adjustable circularly polarised dielectric resonator antenna with slotted ground plane

Circularly polarised (CP) dielectric resonator antennas (DRAs) with a slotted ground plane are proposed. The proposed CP design is achieved by embedding two pairs of unequal slots in the finite ground plane of the feed substrate, which results in the excitation of two near-degenerate orthogonal modes and leads to CP radiation. For the proposed design, a large CP bandwidth, determined from 3 dB axial ratio, as high as 2.7% is also obtained. The resonant frequency can be tuned by changing the slot length. This proposed design is applicable to DR antennas where post-manufacturing trimming is required. Details of the proposed designs and experimental results of the constructed prototypes are presented.