A Circularly Polarized Hybrid Dielectric Resonator Antenna With Wide Bandwidth and Compact Size

A circularly polarized (CP) hybrid dielectric resonator antenna (DRA) with wide bandwidth and compact size is proposed in this letter. Three CP modes can be combined together for broadband operation, which are the cross-slot mode, the DR mode, and the distributed patch mode, respectively. The cross-slot functions as both a radiator and part of the feeding structure, providing the first CP mode and excites the other two CP modes, respectively. The 2 x 2 distributed patch is inserted inside the DR. The DR and the patch can generate another two CP modes without enlarging the DR size. Through optimization, these three CP modes can be combined to achieve a wide operating bandwidth with a compact size of 0.39 x 0.39 x 0.14 ?(3)(0) (?(0) is the free-space wavelength at the center frequency of 3.5 GHz). A prototype was fabricated and measured for demonstration. It has an impedance bandwidth of 38.9% (2.9-4.3 GHz), an axial ratio bandwidth of 34.3% (2.9-4.1 GHz), and a realized gain between 5.6 and 6.7 dBi.