Failure of homogeneous multilayer approximation for plasma waveguides

It is generally not possible to obtain exact analytical solutions for electromagnetic fields in inhomogeneous media. However, in the considered cases an approximate procedure can usually be employed. This procedure involves the division of the inhomogeneous layer into a number of homogeneous sections. The present investigation is concerned with a case in which the described procedure does not provide the desired solution, taking into account a plasma waveguide consisting of an inhomogeneous isotropic cold plasma slab. Attention is given to the propagation along a homogeneous multilayer plasma slab, and the propagation along an inhomogeneous plasma slab.