Broadband VHF sources locating system using arrival-time differences for mapping of lightning discharge process

This paper presents a three-dimensional lightning discharge mapping system using arrival-time difference of broadband VHF electromagnetic pulses (20-200 MHz) methodology. The system consists of four circular plate antennas; three of which are placed to form two perpendicularly crossed-short base lines, with the fourth located at some distance. The directions of the electromagnetic radiation sources are determined using perpendicularly aligned antennas whereas the 3-D positions are obtained using all the four antennas. Broadband pulses arrival time differences are estimated incorporating time-domain signal analysis and the least-squares error method is applied to the detected broadband pulses to estimate the time delay with the quadratic interpolation technique utilized to achieve the resolution less than 1 ns. In this paper, the implementation of the system along with the successful reconstruction of the lightning discharge progression in 2-D and 3-D space is described. Additionally, instances of observation results of the cloud-to-ground and ground-to-cloud lightning discharge have been presented.