Satellite and ground observations of HIPAS VLF modulation

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Abstract
Joint experiments between the new Japanese satellite EXOS‐D (Akebono) and the HIPAS (High Power Active stimulation) facility located at Fairbanks, Alaska were made in 1989. The HF radiation was modulated in amplitude by 2.5 kHz signal. On November 28, 1989, EXOS‐D detected the VLF signal at an altitude of 2300 km with an E field of 15 μV/m and a B field of 0.25 pT. The angle between the wave normal and the geomagnetic field was found to be less than 20°.Simultaneous ground observations were made using loop antennas at a distance about 35 km from HIPAS. The 2.5 kHz signal amplitude there at the time of the satellite observation was 1.3 pT. If this wave magnetic field is assumed to be due to an ionospheric AC current of 0.65 A, the signal strength at the satellite is roughly consistent within a factor of 3, which is much better consistency than those observed by James et al. (1984).