Practical design considerations for reconfigurable intelligent surfaces

The reconfigurable intelligent surface (RIS) has recently emerged as a very appealing technology to manipulate electromagnetic waves in a propagation environment. The RIS is a planar surface that consists of a large number of active tunable elements with no RF chain. Hence, it poses no significant cost burden when added to the existing cellular network architecture. In this chapter, we discuss the basic hardware architecture of RIS, followed by various tuning mechanisms adopted in the control of RIS elements. Additionally, some physical limitations that define the bandwidth-phase relationship, the effect of incident angle and the quantization effect, in the design of RIS unit cells have also been discussed in this chapter.