Wave propagation in random media: a comparison of two theories

The variance of the irradiance scintillations of a wave that propagates in a random medium is calculated by using the extended Huygens–Fresnel principle (EHFP) and then compared with numerical solutions of the parabolic equation for the fourth-order statistical moment. Results are presented for the propagation of Gaussian beams and plane waves in a two-dimensional random medium with a Gaussian correlation function. Various formulations of the EHFP are considered, with particular emphasis on the often-used phase approximation of the EHFP. It is shown that, although both methods predict saturation, there is a considerable disagreement at moderate ranges.