Broadband and High-Front-to-Back-Ratio Dielectric Resonator Antenna With a Compact Ground Plane

Maintaining a unidirectional broadside radiation pattern for a dielectric resonator antenna (DRA) on a compact ground plane is challenging. In this paper, a broadband DRA is designed and investigated, achieving high front-to-back ratios (FTBRs) despite the small ground plane. The DRA is excited to function as a horizontal magnetic dipole, which interacts with orthogonal horizontal currents on the ground, forming an orthogonally complementary antenna structure. The magnetic field of DR and the electric currents on the ground are coupled to maintain in-phase excitation. By carefully optimizing the ground plane, the magnitude of the complementary sources can be adjusted, improving the FTBRs. This design enables stable unidirectional radiation across a broad bandwidth of 48.16%. A prototype is fabricated and experimentally validated, demonstrating an FTBR exceeding 18 dB across the measured operating frequency range of 2.27–3.71 GHz (48.16%).