Radars for Probing the Terrestrial Ionosphere: an Overview of Old and New Techniques

The first instrument that exploited the radar principle was used to investigate the properties of the ionospheric reflecting layers. Over the decades since then, the techniques have improved and many other types of probing have been developed. The presentation summarises various methodologies, with particular focus on the vertical sounding, and describes the recent improvements, taking into account that in the last years the classic vertical soundings have been joined by new measures of the attenuation undergone by the signal, that are useful to improve the knowledge of the characteristics of the medium.