Beam-Deflection Using Gradient Refractive-Index Media for 60-GHz End-Fire Antenna

This communication describes a beam-tilting technique for planar dipole antennas utilizing gradient refractive-index metamaterial (GRIM) unit-cells. Beam-deflection mechanism is based on the phase shift phenomena resulting from the interaction of the EM waves with media of different refractive-indices implemented using GRIM unit-cells. The GRIM unit-cell comprises of a stub-loaded I-shaped resonant structure that is directly integrated onto the dipole antenna. The simulation and experimental results show that an antenna with a 5 × 4 array of GRIM unit-cells can steer the main beam in the E-plane by +26° with respect to the end-fire direction over 57-64 GHz. The antenna exhibits 4-dB gain enhancement and S11 better than -10 dB from 57-64 GHz. It is also shown that a quad-feed dipole antenna with GRIM arrays can deflect the beam by ±56°.