Single-Layer Focusing Gradient Metasurface for Ultrathin Planar Lens Antenna Application

A single-layer focusing gradient metasurface (MS) built by one element-group is proposed. The element-group is designed by well connecting the phase shift range of two similar single-layer elements under the condition of transmitting efficiencies over 0.7. The proposed MS can focus the propagating plane wave on a point and a patch antenna is placed at its focus to build a high-gain planar lens antenna. This lens antenna achieves pencil-shaped far-field radiation pattern with a simulation peak gain of 16.7 dB at 10 GHz. The single-layer structure makes it easy to fabricate the MS with low profile and satisfying performances. Finally, the MS and the patch antenna are fabricated, assembled, and measured. The measured results are in good agreement with the simulations.