Statistical analysis of vhf electromagnetic radiation from lightning discharges

Abstract

We examine spectra of VHF electromagnetic (EM) waves obtained by a VHF Digital Broadband Interferometer (DITF) operated on the ground. The DITF is a two- and three-dimensional VHF source mapping system for VHF EM waves in band between 25 and 100MHz based on a technique of the broadband digital interferometry. We divide leaders into two classes by an aspect of leader development based on three-dimensional discharge channels. The spectra of VHF EM waves associated with the leaders progressing to the ground peaks around 25MHz, while that of the leaders propagating horizontally inside thundercloudspeaks around 40MHz. © 2011 The Institute of Electrical Engineers of Japan.