Propagation of Partially Polarized Waves in a Slightly Anisotropic Medium

The behavior of partially polarized waves in a homogeneous, dispersive medium with small anisotropy is considered. The field solutions for a medium specified by a tensor permeability are derived from Maxwell's equations. A power coherency matrix and a brightness temperature matrix are defined and discussed. The tensor equivalent to the equation of radiative transfer for an emitting and absorbing medium is derived from a form of Poynting's theorem, and the general solution to this equation for the brightness temperature matrix is given. The assumptions and restrictions employed in the development are reviewed and the effect of relaxing them is discussed. Finally, the method is applied to a simplified version of absorption by Zeeman‐split resonance lines.