Ionosondes - A Study on the Use of Electromagnetic Wave Propagation as a Technique to Observe the Ionized Layer of the Earth’s Atmosphere

The terrestrial atmosphere can be understood as an immense laboratory that hosts various physical phenomena. One of the main effects of the interaction of solar radiation in the upper atmosphere is the ionization of its gaseous constituents. This ionization, which starts at around 60 km and extends to the limits of the atmosphere, forms the ionosphere. This ionized layer develops an important role in the propagation of radio waves. This work presents a brief theory on the propagation of electromagnetic waves in the ionosphere. In this purpose, the ionosonde is shown - a device that makes use of radio techniques for ionospheric sounding. Are shown examples of ionograms and is explained its interpretation to obtain ionospheric  parameters.