Purpose - To devise a parametric study using a new application of the boundary element method (BEM) and to propose an efficient approach for speeding up the computation time of the BEM based on neural networks (NNs). Design/methodology/approach - A 3D finite elements formulation is combined with radial basis function NNs to speeding up the computation time. Findings - The paper shows how to estimate the role of thin slabs filled with unconventional media in order to increase the coupling values when placed between two metallic strips in a coupled microstrip line layout or to improve the shielding properties when used as absorber. Research limitations/implications - The numerical results here presented are not bianisotropic but can be easily extended to take into account bianisotropic media. Originality/value - The formulation is one of the only with the potential for investigating unconventional bianisotropic media like Chiral materials which are seen as one possible route to achieving double negative media.