ABSTRACT
This chapter considers RF, VHF and UHF electromagnetic radiation associated with lightning. Selective observations have shown that different phases of the lightning formation make different contributions; in particular, the return-stroke generates the low-frequency components while the VHF-UHF is mainly generated by the intracloud mechanisms and the return-stroke precursors. The system makes it possible to monitor the electromagnetic activity of lightning both individually for each discharge and for the whole duration of the storm. The imaging system uses the interferometry mapping technique. P. Richard and G. Auffray give details on the application of this technique to the analysis of radiation from lightning. A three-dimensional reconstruction of the sources and the variations characteristic of the corresponding electrical field at ground level indicate that the VHF-UHF sources follow the discharge lightning channels, conventionally referred to as "stepped leader," "dart leader" or "intracloud leader.".
