Transionospheric propagation at the boundary of radio transparency range: results of Russian space experiments and plans for low orbiting pilot space station

To ensure good design, as well as reliable and stable operation of radio systems using radio communication channels, it is essential to determine the ionospheric spatial structure. Installation of the ionosonde on-board the satellite provided the optimum possibility for determining the ionosphere spatial structure. The ionosonde emits radio waves that propagate throughout the ionosphere and allows a study of both the topside and the bottom-side ionosphere. The method of transionospheric sounding is based on the application of frequencies crossing throughout the ionosphere at the boundary of the radio transparency range. The transionospheric sounding method does not demand additional equipment, as it generally makes use of the available on-board and ground-based ionosonde equipment. In combination with the ground-based and topside sounding, this method forms an optimum closed system of ionospheric radio sounding in the frequency range that corresponds to plasma concentrations of the region under investigation.