Determination of the electromagnetic fields radiated from the ARES EMP simulator

This paper describes a calculational model for evaluating the electromagnetic (EM) fields produced by the ARES simulator outside its normal working volume. The model employs transmission line theory to determine the simulator current distribution. Once this is determined, the radiated fields are computed approximately using the Norton surface-wave formalism. The transient electric and magnetic fields on the ground are calculated using a fast Fourier transform (FFT) and are compared with experimental magnetic field data. Accuracies on the order of 30% in the peak fields are noted in much of the data. The fields in the air above the Earth also have been calculated, and the relative importance of the Norton surface wave in the overall solution has been clarified. This model and its resulting PC code provide a useful tool for further studies of the impact of radiated EM fields on distant electrical systems. The results presented are directly applicable in defining and evaluating the EM environments produced by ARES, or by similar bounded wave simulators, and in assessing and limiting the possible biological effects of pulsed radiation