Comparison between different types of green´s function factorization for the BMIA/AIM method

Three different formulations that allow to extend the BMIA/AIM method to the analysis of large dielectric stratified structures are introduced. These techniques lead to an approximate form of the multilayer Green´s function, valid in the region where the thickness of the substrate can be considered small compared to its transverse dimension. This approximate form results as the product of three terms: two dependent by the source and observation longitudinal position, the other by its transverse distance. The first technique makes use of a suitable description of the Green´s function in terms of discrete complex images. The remaining ones deal with the evaluation of the Green´s function along the steepest descent path integration and a least-squares interpolation formulation, respectively.