Study of the earth's ionosphere by reception of radio waves from satellites

Abstract

A study of ionospheric scintillations by the reception of signals from the Russian satellite 1962 Cosmos I was undertaken. The data were obtained at the Sagamore Hill Radio Observatory, Hamilton, Massachusetts, of the Air Force Cambridge Research Laboratories. The satellite transmitted at a frequency of 20 Mc/s and it was found possible to receive the first two harmonics at 40 Mc/s and 60 Me/s. A high percentage of scintillation was observed on all nighttime transits of the satellite. No marked variation of scintillation index with elevation angle was observed. The scintillation index varied with wavelength as lambda^(0.78) for magnetically quiet days and as lambda^(0.36) for magnetically disturbed days. A pronounced latitude dependence of scintillations was observed. The onset of scintillations occurred at a sub-ionospheric latitude (referred to a height of 300 km) of 35 degrees North for magnetically disturbed days. A zone of almost uniform scintillation exists beyond a latitude of 41 degrees North. On certain occasions the satellite passed through clouds of irregularities, the size of which were about 550 km. A model of the non-uniform distribution of irregularities in the ionosphere is proposed as a result of this study.