IRS in the Near‐Field: From Basic Principles to Optimal Design

Modern communication systems leverage the randomness of wireless channels to improve performance. This is accomplished by the subtle design of the transceiver whilst treating the propagation channel as an uncontrollable entity. However, the recent advances in meta‐materials have made possible electromagnetic wave manipulation through intelligent reconfigurable surfaces (IRSs). Smart propagation environments enabled by IRSs have therefore attracted much attention in the context of sixth‐generation communication systems. In this chapter, we present the basics of IRS‐aided communication, as well as delineate the specifics of near‐field operation.