  A theoretical framework for the quasi-monochromatic electromagnetic (EM)
processes such as excitation and propagation of long wave packets in
dispersive, dissipative, bianisotropic media with weak and slow nonlinearity is
developed. The time-dependent EM fields associated with such processes are
expressed as products of two functions: the slowly varying complex amplitude
(SVCA) and the quickly oscillating carrier. The material parameters are treated
as operators acting on time-dependent EM fields. By expanding these operators
in the Maxwell equations in a series with respect to a small time scale
parameter a system of equations for the SVCAs of the EM fields in such media is
formulated. In the linear case, the dynamic equations for the SVCAs that
correspond to the transverse components of the electric and magnetic fields
resemble the vector transmission line equations. The obtained system of
equations is used to derive the dyadic Green functions for the SVCAs of the EM
fields in bianisotropic media. This framework is applied for modeling
propagation of partially coherent EM radiation in a material whose parameters
may depend on the amount of the EM energy that has passed through it. The same
framework can be used in studying propagation of modulated EM waves through a
waveguiding system that includes bianisotropic metamaterial components.
