Plane waves in decomposable bi-anisotropic media

The class of decomposable bi-anisotropic media was recently defined to cons ist of media in which any electromagnetic field can be decomposed in two in dividual electromagnetic fields satisfying certain conditions for the elect romagnetic fields. Also it was shown that, for a medium in this class, the fourth-order Helmholtz determinant operator governing the basic electromagn etic fields can be factorized, i.e., expressed as a product of two second-o rder operators. In the present, paper, plane-wave propagation in the genera l decomposable medium is studied. Analytical solutions are derived for the dispersion equation and the polarizations of the eigenwaves are also determ ined in analytic form. As a check the expressions are applied to a medium w ith previously known solutions. In an appendix, conditions for the medium d yadics of the decomposable bi-anisotropic medium are derived for the case w hen the medium is lossless.