Effects of propagation on the return stroke radiation fields


  • Vernon Cooray


It is shown that a simple mathematical model could be used to predict the propagation effects on the radiation fields to a high accuracy under most of the cases of interest. Propagation effects on a large collection of radiation fields from first return strokes measured over seawater are studied by using this mathematical model. The theoretical results are compared with the available experimental data and a good agreement is found between them. One important conclusion of the study is that the localization of the lightning return strokes by the time of arrival method could be greatly improved, under low conducting ground conditions, by selecting one of the following as reference points in the time measurement: (1) a point in the initial rising part of the radiation field whose amplitude is less than about 50% of the initial peak or (2) the peak of the first or the second derivative of the radiation field.