Efficient Incorporation of Normal Susceptibilities into Implicit IE-GSTC Metasurface Forward Solver

The generalized sheet transition conditions (GSTCs) are combined with integral equations (IE) in order to efficiently compute the scattering response of metasurfaces that exhibit both tangential and normal polarization responses. To this end, a particular form of IE-GSTC method, known as the implicit IE-GSTC solver, is employed and augmented to incorporate both tangential and normal susceptibilities. This augmented solver offers two key benefits. First, it maintains the same computational complexity as the equivalent solver that only considers the tangential polarization response. Second, it establishes a mapping between metasurface models with tangential and normal susceptibilities and non-local metasurface models solely characterized by tangential properties. This offers valuable insights into the behavior and design of non-local metasurface structures.