Mathematical model of radio sounding of the ionosphere from satellite at heights below the electron density maximum

The mathematical model of radio sounding of the horizontally inhomogeneous ionosphere is proposed. Its validity is confirmed by the results of the experiment carried out onboard the Mir orbital station at heights below the electron density maximum in the ionosphere. In its turn, the mathematical model makes it possible to explain the appearance of new traces on ionograms obtained in this experiment as the result of the existence of backward trajectories toward the satellite during the radiowave propagation in the inhomogeneous ionosphere.