Intelligent Reflective Surfaces – State of the Art

This chapter presents a comprehensive overview of the reconfigurable intelligent surface (RIS). It gives the theory of operation of RIS, which is similar to the aperture antennas. The chapter shows various potential application scenarios of the RIS in future wireless communication and health care technologies. It discusses the differences between RIS with relay technology and provides a comparison of RIS with existing technologies. A new class of emerging metasurface that is coded and programmable metasurface, will consequently bridge the gap between the digital domain and the electromagnetic domain. The chapter also discusses the various important functionalities associated with RIS. It also presents a significant application of the RIS operated in the near-field as a transmitter. The chapter introduces a typical architecture of the RIS with three basic layers, and then discusses the role and key features of every sub layer in detail.