Fresnel-type Fading On Satellite Records At Low Latitudes

Abstract

Fresnel-type fading patterns have been observed on recordings of geostationary and travelling satellites made at three low-latitude stations in East Africa. The occurrence is greatest in the time periods 05–08 and 18–22 local time, at the June solstice. The patterns seem to be produced by patches of increased ionization some 1.5–25 km in extent at heights corresponding to sporadic-E levels and the lower F-region. The sizes show an increase with height. On occasions the patterns exhibit repetition with intervals of 4–30 min. The equations used in determining the height of the patches are reviewed. The results are compared with those from middle latitudes. A possible connection with sporadic-E is discussed.