Susceptibility Invariance and Duality‐Matching Condition for Perpendicular‐Motion Metasurface

Abstract

Time‐varying metasurfaces have recently emerged as a promising platform to observe exotic wave behaviors in space‐time systems. In this paper, it theoretically reveals invariant susceptibility parameters for perpendicular‐moving metasurface. Duality‐matching condition is derived by utilizing generalized sheet transition conditions (GSTCs) combined with Lorentz transformation (LT). A metasurface that satisfies the duality‐matching condition can hold its susceptibility parameters when it moves perpendicularly toward the sources. The moving‐invariant behavior is further discussed in time‐varying media and additional reflection is found to be inevitable if the constitutive parameters is discrete in time.