Plane-wave propagation in decomposable bianisotropic media

Plane-wave propagation is studied in the most general bianisotropic medium in which the electromagnetic wave can be split into two eigenwaves with cer tain polarizations depending on two arbitrary directions in space. Hence th e whole problem splits into two parts. The dispersion dyadics of the materi als seen by the eigenwaves are derived and the refractive indices are solve d for arbitrary direction of propagation. Also, a general expression for th e eigenpolarizations is found. The theory is applied to some cases Sitting the requirements of the media.