Beam-Tilting Antenna With Negative Refractive Index Metamaterial Loading

A beam-tilting antenna with negative refractive index metamaterial (NRIM) loading is proposed for WLAN applications. The proposed antenna is composed of a double-feed dielectric resonator antenna (DRA) and 1 × 4 NRIM array, which are fixed over and in the middle of the DRA. The proposed NRIM unit cell comprises a fractal cross-ring resonator structure and performs a negative refractive index in the band from 5 to 5.5 GHz. When the electromagnetic (EM) waves enter a medium with a negative refractive index, the direction of propagation of the EM wave can be changed. Therefore, beam-tilting can be implemented by using the DRA cooperating with the proposed NRIM array. The simulation and experimental results show that the beam-tilting antenna can steer the main beam by ±38° in the xoz-plane over 5-5.5-GHz band. The reflection coefficient of the antenna is better than -10 dB in the band from 5 to 5.5 GHz. Furthermore, the measured results have a good agreement with simulated ones.