Linear time-invariant system theory for numerical lightning transfer function determination

To obtain lightning transfer functions of realistic systems from numeric simulation generally is a difficult task. The long duration of typical lightning pulses and the associated low-frequency spectra pose challenges to numerical full-wave electromagnetic solvers which, in particular, are associated with stability issues and long computation times (D. Prost, F. Issac, T. Volpert, W.Quenum, and J.-P- Parmantier, IEEE Trans. on Electromagn. Compat., 55, no.2, (April 2013), pp. 378–384). This applies both to time and frequency domain numerical techniques.