An Inverted L-Shaped Multi-Layer Reconfigurable Intelligent Surface for THz Communications.

Realizing the gains of reconfigurable intelligent surfaces (RISs) for terahertz (THz) frequencies requires the practical design of reconfigurable surfaces. In this paper, we propose the design of a compact reconfigurable surface composed of meta-materials equipped with a voltage-controlled tunable dielectric substrate. We show that controlling the tunable dielectric substrate's dielectric properties is conducted by varying the voltage source at each unit cell. We show that the use of independent voltage sources at each unit surface introduces a linear and progressive phase variation to the reflected signal from the surface of the RIS. The reflection coefficient performance at each voltage level conveys the phase shifts for different dielectric constants. As a result, we derive the maximum beam-steering angle from the phase shifts to redirect the signal in the intended direction.