A robust approach for the derivation of closed-form Green´s functions

Spatial-domain Green´s functions for multilayer, planar geometries are cast into closed forms with two-level approximation of the spectral-domain representation of the Green´s functions. This approach is very robust and much faster compared to the original one-level approximation. Moreover, it does not require the investigation of the spectral-domain behavior of the Green´s functions in advance to decide on the parameters of the approximation technique, and it can be applied to any component of the dyadic Green´s function with the same ease