  The problem of radio wave reflection from an optically thick plane monotonous
layer of magnetized plasma is considered at present work. The plasma electron
density irregularities are described by spatial spectrum of an arbitrary form.
The small-angle scattering approximation in the invariant ray coordinates is
suggested for analytical investigation of the radiation transfer equation. The
approximated solution describing spatial-and-angular distribution of radiation
reflected from a plasma layer is obtained. The obtained solution can be
applied, for example, to the ionospheric radio wave propagation.
