Comparison of R2SPG waveforms with simulated EMP

Measurements were made on three cables in the electromagnetic pulse (EMP) testbed aircraft (EMPTAC) using the horizontally polarized dipole (HPD) and TRESTLE EMP simulators as well as the random repetitive square-wave pulse generator (R²SPG) and a damped sine-wave generator. The currents were analyzed in both the time and frequency domains. The R²SPG produced a greater induced current, by a factor of 4 to 60, than either of the EMP simulators. The pulsewidths and the frequency content were similar for all of the test points obtained with the R²SPG and EMP simulators, and, by careful selection of the charge and feed cables, cold be made essentially identical. This confirms the assumption that the R²SPG excited the cable system at its resonant frequency. The amplitudes of the R²SPG and the damped sine-wave generator were closer to each other in both the time and frequency domains. The damped sine-wave generator was able to couple more energy to the cable when the lowest carrier frequencies (0.1 and 1 MHz) were used. On the other hand, the damped sine-wave current transient had a much narrower bandwidth than the R²SPG-induced current transient. Thus the R²SPG waveform was much more suitable for upset testing than the damped sine-wave