Vector forward scattering theorem

The concept of energy balance is applied to compute the total loss (or extinction) resulting from a partially polarized plane wave impinging upon a scatterer. It is shown that under the far-zone condition, the application of the stationary phase approximation leads to an expression relating the total loss to the Stokes parameters of the incident wave and the forward scattering amplitudes of the scattered wave. This relation may be referred to as the vector forward scattering theorem. For a linearly polarized incident plane wave, the result reduces correctly to the standard forward scattering theorem in the literature.