A VHF broadband interferometer for lightning observation

A VHF broadband interferometer is a system to locate sources of the radiation events at VHF band by extracting the differences of phases at various frequency components of Fourier spectra between a pair of antennas. Lightning images are derived by sensing the electromagnetic waves radiated from lightning discharge process such as negative stepped leader. Using the system, lightning observations have been carried out firstly in Hokuriku area Japan during the onset of the winter season for rocket triggered lightning experiment, then, in Darwin Australia, and so on. Based on the successful results, the interferometer system is deployed on the GLIMS (Global Lightning and sprIte MeasurementS) mission in the International Space Station to detect and locate the VHF impulses emitted by lightning from space.