Spatial Autocorrelation of the Level of Radio Signal Amplitude at Oblique Propagation in the Ionosphere

Fluctuations of the amplitude level of a wave that propagates through a randomly inhomogeneous medium with regular reflection are considered. Analytical expressions for dispersion and amplitude correlation functions are derived in the parabolic model of a regular ionospheric layer inside the layer and at the exit from it. Special attention is paid to the study of the reflection area, where the conditions for the applicability of the geometric-optics method are violated. The results are analyzed numerically for ionospheric sounding under different conditions.