E and DE/DT waveshapes for narrow bipolar pulses in intracloud lightning

Wideband electric field and dE/dt waveforms were recorded and digitized at a 100 MS/s rate at KSC during the summer and fall of 1989. These waveforms were combined to produce composite electric fields with an effective bandwidth of 3 to 50 MHz. Bipolar electric field pulses are characterized in terms of their E and dE/dt waveshapes. Half width mean durations were found to be 1.83 and 3.64 microseconds for negative and positive bipolar pulses respectively. Twenty of thirty of these pulses were found to occur independently of any other lightning activity. Analysis of the frequency content of these pulses as a function of time shows that radiation at different frequencies peak at different times. In addition to the initial peak and subsequent overshoot in the composite E waveshape, secondary humps following the initial peak are characterized according to their time of occurrence within the pulse. THe 156 narrow negative bipolar pulses and 10 positive narrow bipolar pulses are analyzed. The dE/dt signatures range from impulsive variations lasting several microseconds both before and after the initial peak of the electric field pulse, to smoother variations closely associated with peak.