Tailoring Radiation Patterns in Broadband With Controllable Aperture Field Using Metamaterials

Metamaterials (MTMs) have advantages to control electromagnetic (EM) waves with high flexibility. However, the application of MTMs in antennas has mainly focused on controlling the phases of EM waves (e.g., to transform spherical waves into planar waves in flat lens and Luneburg lens). In this work, we experimentally demonstrate a method to control the radiation patterns in broadband using MTMs. By controlling the inhomogeneous refractive-index distribution of MTMs, both amplitudes and phases of EM waves on the antenna aperture are designed as required. We present an example to produce a new MTM lens antenna to possess high gain and low sidelobes simultaneously. Experimental results show excellent performance of the antenna in a broad band from 12 GHz to 18 GHz.