A Tunable Metamaterial Reconfigurable Intelligent Surface for 5G Applications

This paper presents a Tunable Unit Cell for Reconfigurable Intelligent Surface (RIS) for Beamforming and Beam steering applications in the fifth-generation mobile communications (5G) range. The proposed RIS unit cell is based on a printed Split-Ring Resonator (SRR) loaded with a Varactor Diode, which connects two circular loops at the top, and a ground plane at the bottom, resulting in a total area of
$0.28\times\lambda_{0} 0.28\times\lambda_{0}$
. The design of the RIS unit cell was carried out using a full-wave electromagnetic solver. The obtained numerical results demonstrate a reflection phase shift up to 90° and a reflection magnitude over -20 dB at 28GHz. A
$10\times 10$
-unit cell array was designed to check the radiation performance. The proposed Reconfigurable Smart Surface could be applied in future wireless communication systems.