In-Plane Feed Antennas Based on Phase Gradient Metasurface

We propose the design of in-plane feed antennas (IPFA) based on phase gradient metasurface (PGM). The in-plane feed is realized using PGM with large in-plane phase gradient, which can couple normally incident waves efficiently into surface waves along the surface. This is different from conventional reflector antennas and reflectarray antennas, where the focus lies above the reflector. As an example, an IPFA is demonstrated, which is composed of a superthin PGM and a waveguide feeding structure. Due to the large phase gradient of the PGM toward the feeding waveguide, incident waves can be coupled as surface waves into the waveguide; whereas transmitted waves can be radiated out along the normal of the PGM. Both the simulated and experimental results verify the high gain and high efficiency of the IPFA with in a broad band in 3.0-3.2 GHz.