Green´s functions and EM fields direct terms in printed circuits

The Green´s functions and the fields pertaining to a unit source in a layer of a multilayered medium present the same direct terms as a source in a homogeneous medium, thus of a spherical nature. This study shows that when the source is at an interface additional direct terms arise that present a more complex spherical-cylindrical nature. In spite of that they can be formulated analytically and their amplitude is discovered to be dependent on the EM properties of both media but not on their thickness.