Power transfer in a two-winding transformer: from 1-D propagation to an equivalent circuit

Electromagnetic propagation at normal incidence through a multilayer medium is a problem which has already been solved in optics. We use here the same approach to find the equivalent circuit of a transformer. Using complete Maxwell's equations, a fully equivalent electrical circuit is associated to any layer. Then, for three materials (conductor, insulator, ferrite), a lumped element circuit is designed as a low to medium frequency approximation. Finally, linking altogether these circuits, leads (for a two-winding transformer) to a recently proposed equivalent circuit.