Fitting method of the simulated HEMP waveform by the doubleexponential function

An important nature of the double-exponential function, which is used to describe the typical high-altitude electromagnetic pulse (HEMP) waveform in many standards and publications, is studied by the numerical method. Based on the function nature it is discussed in details the relation of the physical parameters of the simulated HEMP waveform and the character parameters of the double-exponential function. Here the physical parameters of HEMP include peak value, rise time, fall time and full-width at half-maximum amplitude (FWHM). A simple and effective method is proposed to evaluate the character parameters of the function from the physical parameters. And it's effectivity and reliability is validated by evaluating the HEMP parameters defined by IEC and by the numerical fitting of a measu