Drude Model-Based Metamaterial Cover for Wideband Radiation Pattern Roundness Improvement

Antennas placed near dielectric covers commonly suffer from radiation pattern distortion due to guided waves. This study presents a theoretical analysis and derives conditions for suppressing guided waves in uniaxial anisotropic metamaterials. It is also proved that metamaterials described by the Drude model offer the potential for achieving wideband suppression of guided waves. To validate this approach, four-dipole ring (FDR) antennas arrangement beneath a dielectric cover is investigated. The study shows that the proposed metamaterial-based cover (meta-cover) incorporating Drude-model-inspired unit cells improves the radiation pattern un-roundness from 17.6 dB to 5.2 dB ranging from 5 GHz to 6 GHz, and enhances coverage efficiency from 42.4 % to 84.7 %. The proposed approaches benefit antenna radiation pattern control over a broad bandwidth.