Wave reflection from randomly inhomogeneous ionospheric layer: 1. The method of describing the wavefield in a reflecting layer with random irregularities

摘要

It has been previously proposed to describe wave propagation in inhomogeneous media in a small-angle approximation with the aid of a double weighted Fourier transform (DWFT) method. This method agrees with the methods of geometrical optics, smooth perturbations, and phase screen in domains of their applicability; therefore, it can be employed to solve direct and inverse problems of radio wave propagation in multiscale inhomogeneous ionospheric plasma. In this paper, for the DWFT wide-angle generalization a wave equation is preliminary reduced using the Fock proper-time method to a parabolic equation that then is solved by the DWFT method. The resulting solution is analyzed for the case of wave reflection and scattering by a layer with random irregularities and linear profile of average permittivity. We show the transformation of this solution into strict results in the absence of irregularities and in the single-scatter approximation, including backscattering, during weak phase fluctuations. Under certain conditions, the solution takes the form of the small-angle DWFT with respect to refraction in the layer and backscatter effects. Spatial processing in source and observer coordinates brings a beam of received waves into one wave without amplitude fluctuations, which allows an increase in resolution of vertical ionospheric sounding systems.