The effect of atmospherics on tuned circuits

The effect of an aperiodic disturbance on a tuned system is considered theoretically, and a method is discussed for determining the Fourier component of the amplitude spectrum of the disturbance at the resonant frequency of the system. The available information on the lightning discharge is then summarized, and a prediction made of the amplitude spectrum of the atmospheric radiated from the main return stroke and its variation with distance from the source. Some experimental work is described in which statistical amplitude spectra of atmospherics from far and near storms are measured by recording simultaneously on tuned and untuned channels. The results obtained are found to be in keeping with the predictions from earlier work if allowance is made for scatter in source distance.