The statistical characteristics of the point source field in inhomogeneous ionosphere with electron density fluctuations are studied by using the integral representation by partial waves taking into account diffraction effects. The parabolic equation in the curved local ray coordinates for a complex phase of individual partial wave is considered and its solution in the incident field caustic region is discussed. The moments of total field, average value and average energy, are constructed by using the first and second approximations of the complex phase.