Recent Advances on Multi-Scale Wave Manipulation through Reconfigurable Intelligent Surfaces

The Smart ElectroMagnetic Environment (SEME) concept is revolutionizing the design of wireless systems, exceeding current-generation capabilities. SEME manipulates electromagnetic waves to align with performance objectives, challenging traditional fixed propagation environments. Electromagnetic Skins (EMSs), including reconfigurable passive two dimensional artificial structures, represent a crucial technology within this framework. These devices enable to perform advanced wave manipulation functionalities (e.g., anomalous reflection, beam shaping) through meta-atomic adjustments of their electrical properties (e.g., through electronically-controllable components). Despite complexity, EMSs offer cost-effective alternatives to traditional wireless equipment, prompting substantial research in the field. This work is aimed at discussing some of the latest RIS synthesis and wave manipulation developments, offering insights into advanced design and implementation strategies.