Design of Anomalous Reflectors by Phase Gradient Unit Cell Based
Digitally Coded Metasurface
Abstract
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,
$(\theta_r=30^0,\phi_r=0^0)$,
and subsequently, the far-field plots are generated. Furthermore, these
phase profiles are used to generate 3D-CAD models of the 1-bit and 2-bit
metasurfaces using CST, and the desired far-field patterns are obtained
having half-power beamwidth (HPBW) of $5^0$. 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 (PEC).
The proposed design is suitable for V2X communications and can be scaled
to other frequencies.