Polarization-Controlled bifunctional antenna based on 2-D Anisotropic Gradient Metasurface

A novel 2-D single-layer reflective phase gradient metasurface (RPGM) with polarization-independent property is proposed based on the generalized Snell's law of reflection. The well optimized RPGM consists of 24x24 suitably selected elements with paraboloidal phase distribution along x direction and -45 degrees phase gradient along y direction, respectively. Pure focusing effect and anomalous reflection are unambiguously observed by illuminating with different polarizations to afford physical insight into the principle of the RPGM. For demonstration and potential applications, a polarization-controlled wideband reflective device with radiation pattern selectivity is proposed based on the specially designed RPGM for the first time. Numerical and experimental results coincide well, indicating that the designed reflective device can work as a reflectarray antenna under excitation of horizontal polarization, and operate as a beam reflector under vertical polarization. More importantly, the reflective device advances in many aspects such as bifunctional radiation patterns, quite broad bandwidth of more than 5GHz (10-15GHz), and also a simple fabrication process based on the convenient print circuit board (PCB) technology. The finding opens up a new avenue to design bifunctional devices in a wide spectrum ranging from microwave to optical.