Analytical Method to Model Spatiotemporal Metasurfaces

This work introduces a theoretical framework to develop fully-analytical and multi-modal equivalent circuits that are applicable to spatiotemporal metasurfaces. Here, time is considered a periodic variable. Thus, classical models for purely spatial structures are generalized to cover space-time scenarios. This paper explores various periodic metastructures from a circuital perspective, considering just time periodicity or space-time periodicities. The performance of the analytical equivalent circuits is validated through an external FDTD code. The results suggest that our analytical model is a powerful tool to describe and design novel and advanced space-time microwave and photonic systems.