Design of circularly-polarized dielectric resonator antenna with wideband feed network

A circularly-polarized (CP) rectangular dielectric resonator antenna (DRA) fed by a wideband feed network is introduced. The feed network is designed by using branch-line structure and named as wideband branch-line coupler (WBLC). The proposed WBLC delivers good impedance matching, equal power splitting and consistent 90° shifting over a wide bandwidth. It is demonstrated that for the presented rectangular CP DRA, the employment of the WBLC, in place of a conventional coupler with narrowband, provides improved characteristics in terms of circular polarization and impedance matching. The antenna prototype with the WBLC exhibits 3-dB axial ratio bandwidth of 47.69% and impedance bandwidth of 48.46% for VSWR ≤ 2.