Development of VLF/LF Bands Interferometer and its Initial Observations

Abstract

We have been developing EM source location system in VLF/LF bands based on broadband digital interferometry to monitor lightning activities in a wide area. Since EM waves in VLF/LF radiated by lightning discharges propagate a long distance, the VLF/LF interferometer locates lightning discharges a few hundred kilometers away from the VLF/LF interferometer. We conducted lightning observation campaign by a prototype of a VLF/LF band digital interferometer and VHF band digital interferometers in Darwin, Australia. Horizontal distances between VLF/LF and VHF band locations show that VLF/LF radiation sources were located near those of VHF source. We succeeded in locating VLF/LF radiation sources associated with return strokes near the ground.