1-bit RIS Unit Cell with Mechanical Reconfiguration at 28 GHz

In this paper, a mechanically tunable unit cell for reconfigurable intelligent surfaces (RIS) is presented. The RIS unit cell design is based on a metallic cylinder with a metallic cone-shaped element placed at one end. Thanks to the two positions provided by the mechanically reconfigurable cylinder, the cone-shaped element produces a phase shift in reflection of 180° at 28 GHz and therefore, giving the 1-bit reconfiguration. A comparison of the cone-shaped element with other types of geometries such as a cube and a cylinder has been performed. Besides, in view of the unit cell design, a cost-effective fabrication using 3-D printing and spray metallization is considered. A study of dimensional tolerances and conductivity values for the proposed RIS unit cell is done. The simulated results show the robustness of the RIS unit cell for both main dimensions and conductivity values for a frequency range between 25 GHz and 30 GHz.