A 500-kHz Sferics Range Detector

Abstract

The high probability of detecting physically limited sferics pulse energies during some part of the overall lightning process was used in the development of a narrow band receiver-detector range sensor. An rf amplifier and linear detector with a band-width of 4.8 kHz was used to monitor sferics at a frequency of 500 kHz. The detector was coupled to a peak-pulse measuring circuit which produced an output with a standard deviation equivalent to ±2600 m from slowly drifting thunderstorms ranging in distance from 2 to 274 km. A range calibration derived from 10-cm radar echo analysis was in agreement with published propagation data. At ranges <40 km, the calibration is nearly linear which suggests the radiation comes from high altitude discharges. At 10 km the peak field strength for sferics was calculated to be 3700 ?V m?1.