Reconfigurable Intelligent Surfaces: A Brief Review on Design Specifications

The reconfigurable intelligent surface (RIS) is a key technology for sixth-generation (6G) mobile networks. RIS consists of small, low-cost reflecting elements that can be dynamically adjusted using a programmable controller. Each of these elements can efficiently reflect a phase-shifted version of the incident electromagnetic wave. This study presents a brief review of the design specifications of RISs. An overview of the general properties and evaluation parameters is presented. A comparison between passive and active RISs is included. Design specifications and suitable materials are highlighted. Finally, crucial issues for deploying RISs in higher frequency ranges are discussed.