Applicability of the Geometrical Optics Approximation in Radio Occultation Experiments: Numerical Simulations

We have used direct simulation of occultation signal using a numerical calculation of the parabolic diffraction equation to analyze variations of signal intensity and phase along the line of linear of Venus satellite during an occultation experiment. As a result we have proved the liner relationship between variations of frequency and intensity of the signal deformed by regular spherically symmetric ionosphere. It is shown that correspondence between energy and frequency parameters of a sounding radio wave proves the reliability of the result obtained from inversion of the occultation data.