Generation of VLF waves in the ionosphere with coherent dual‐site excitation

Abstract

High Power Auroral Stimulation (HIPAS) Observatory and High Frequency Active Auroral Research Program (HAARP) are two radiating facilities in the Arctic region separated by a distance of the order of VLF wavelengths. The current‐carrying plasma in the E region of the ionosphere above each facility can be modulated to radiate VLF waves via HF heating. Experiments demonstrated that VLF waves can be coherently excited by these two facilities through constructive interference that is sensitive to the phase difference between these two sources.