Early Time Analysis of Insulated Antennas Excited by Source Region EMP

The convolution integral of linear systems theory provides the relationship between the response of a system to an arbitrary excitation and the step function response of the system. We define the step function SREMP as a longitudinal electric field with step function time dependence that propagates at the speed of light. It is found that the early time step function SREMP response of an insulated dipole is quasi-linear, i. e., the open circuit voltage, short circuit current, and the load voltage are approximately ramp functions in time. This implies that the dipole response to an arbitrary SREMP will be dominated by the impulse strength of the field at the observation time multiplied by the approximate slope of the step response. This simple relationship is investigated for an arbitrary SREMP time waveform (the reciprocal of the sum of two exponentials) and is found to be quite good as an early time approximation.