Within the framework of scientific division "Ionosphere and radiowave propagation" IZMIRAN conducts research of the ionosphere both as a part of the near-Earth environment characterized by a number of complex plasma phenomena and as a medium for the propagation of radiowaves in various frequency bands (VLF, LF, MF, HF, VHF etc.).  For years various models and effective methods to study these processes and interactions are being developed at IZMIRAN. Nevertheless, due to complexity and diversity of the physical processes and despite the growing amount of experimental data being collected, the ionosphere is still poorly understood and its study is considered to be one of the fundamental problems of the solar-terrestrial physics and geophysics.