Measurement of the radiated electric fields from electrostatic discharge

A system to measure the time and frequency domain characteristics of transient electric fields with risetimes on the order of a nanosecond is described. The response of the system using two broadband electric field sensors (a truncated transverse-electromagnetic horn and a hemispherical antenna) is compared using three different electrostatic discharge sources (a human body through a metallic screwdriver, a finger, and an electrostatic discharge tester). Time-domain electrostatic-discharge radiated electric field (R=1.0 m) waveforms were measured using a broadband (750-MHz) single-shot measurement system in a laboratory with a 6-ns time window. Time to frequency conversion using the fast Fourier transform permitted frequency-domain characteristics to be determined. Since the time-domain waveforms are quite complex. it is difficult to make comparisons in the time domain. Frequency-domain characteristics were therefore examined. The voltage output from both antennas was shown to be quite different below 80 MHz, and somewhat similar above 80 MHz.<>