Design of Anomalous Reflectors by Phase Gradient Unit Cell-Based Digitally Coded Metasurface

In this letter, we propose the designs of 1-bit and 2-bit digitally coded metasurfaces, which achieve anomalous reflection-based beam steering. First, we demonstrate the systematic design flow of coded metasurface using phase gradient digital unit cells to achieve anomalous reflection in the preferred direction for a normally incident plane wave. Initially, the design procedure is analytically implemented to get the phase profiles for 1-bit and 2-bit digitally coded metasurfaces having equal sizes of
$10\lambda _{0} \times 10\lambda _{0}$
(where
$\lambda _{0}$
is the free space wavelength at 5.9 GHz) for a specific reflection angle,
$(\theta _{r}=30^\circ,\phi _{r}=0^\circ)$
, and subsequently, the far-field plots are generated. Furthermore, these phase profiles are used to generate 3-D-CAD models of the 1-bit and 2-bit metasurfaces using CST, and the desired far-field patterns are obtained having half-power beamwidth of
$5^\circ$
. It is observed that the 1-bit coded metasurface produces additional side-lobe levels, which are minimized by use of 2-bit coding. Finally, the proposed 1-bit and 2-bit coded metasurfaces are fabricated, and the anomalously reflected far-field beam is detected by the received power at desired reflection angle and comparing the results with a perfect electric conductor. The proposed design is suitable for vehicle to anything communications and can be scaled to other frequencies.