We present the results of the experiments on studying the mechanism of the appearance of artificial disturbances at the altitudes of the E region when a high-power wave is reflected in the ionospheric F layer. The ionosphere was disturbed for a few minutes by a high-power o-mode radio wave radiated by the transmitters of the "Sura" facility at frequencies 4.3 or 4.7 MHz. The disturbed region was sounded using a partial-reflection setup at a frequency of 2.95 MHz. The influence of the artificial disturbance on the probing signal at altitudes lower than the height of reflection of a high-power wave at 40-100 km was recorded on the basis of measurements of the altitude-time characteristics of the probing-signal amplitude. Possible mechanisms of the influence of the disturbance in the lower ionosphere on the probing radio waves are discussed.