A New Efficient Method of Analysis for Inhomogeneous Media Shields and Filters

In this paper, we discuss the shielding characteristics of an inhomogeneous shield for oblique incidence. The inhomogeneity here considered can be modeled via a continuous spatial variation of the permittivity along the power-flow direction and can be taken into account in the mathematical model involving the transmission line equivalent-circuit representation in terms of a longitudinal-line impedance and a transverse-line admittance varying along the same direction. In order to design a filter or a matching line layout with such a material, new analytical expressions of the reflection coefficient and of the shielding factor for nonuniform dielectric slabs are found. Some numerical examples are also presented for both the TE and TM polarization cases. Index Terms--Distributed parameter circuits, filters, shielding.