Analytical Circuit Models: From Purely Spatial to Space-Time Structures

This work presents an insight into a theoretical framework for deriving fully-analytical and multimodal equivalent circuits for periodic structures, FSSs and general metasurfaces. By including time as a new variable, the classical version of the model can be extended from the analysis of purely spatial structures to time- and spacetime-varying metasurfaces. Several kind of periodic structures are considered from the circuit point of view along the document, being periodic in space, time and spacetime. The performance the analytical circuits is validated via external full-wave solvers, leading the models to become an excellent tool to explore novel and advanced spacetime scenarios.