A generalized solution of the problem of radio wave reflection in a linear conductive layer indicates the following: (1) the height of radio wave reflection depends on the value of the conductivity gradient; (2) only a fraction of the energy of an incident wave is propagating downwards from a reflection point; (3) Doppler frequency depends critically on temporary changes of layer conductivity; (4) the angle of incidence is not equal to the reflection angle at the height of radio wave reflection.