Extended State-Space Finite-Element Formulation to Incorporate Frequency Dependent Surface Models in Time Domain

This study proposes a finite-element formulation that can incorporate the frequency dispersive effects of surfaces composed of fine geometric details without the necessity of generating a refined mesh to capture these details. The finite-element formulation is recast as a state-space model in time domain and the surface is replaced by its own macroscopic state-space model being part of the whole system of equations to be solved. Examples of metallic surfaces containing small circular holes and slots have been successfully implemented. Simulations of these structures have shown memory savings to one tenth and CPU time reduction to one percent.