Fluctuations of VHF field in the vicinity of the maximum frequency of operation (shadow-zone boundary)

Abstract

We apply the mixed integral representation for a two-point propagator to describe propagation of waves in a randomly irregular medium with background refraction. Combining the ideas of the Maslowe technique and the interference-integral technique, we obtain results that generalize the technique of smooth perturbations for a smoothly inhomogeneous background. Moreover, the proposed approach, which describes both weak and strong fluctuations, accords with the phase screen technique and generalizes it to the case of extended media with regularly inhomogeneous background. Using the proposed method, we perform numerical simulations of the average intensity and scintillation index near the shadow-zone boundary for oblique ionospheric propagation of VHF radio waves.