An extension of Schelkunoff´s shielding theory to anisotropic conducting multilayer materials

A wave matrix formulation that describes the coupling through a planar shield of several anisotropic conducting layers is presented in detail. The approach includes all multiple reflections inside the different layers of the shield. The resulting wave matrix can be used to calculate the shielding effectiveness of the shield. As a result it is demonstrated that for specific cases the shielding effectiveness of an anisotropic multilayered shield can be approximated by the shielding effectiveness of an isotropic shield. In addition a finite structure is simulated and it is shown that the method for the infinite structure allows to correctly predict the transition from isotropic to anisotropic shielding effectiveness with respect to frequency.