A short note on the variation of path loss in the atmosphere

• We examine five consecutive years of simultaneous diurnal variation of beacon attenuation and attenuation inferred from the radiometer obtained from six sites in North America.
• The simultaneous diurnal variation of the beacon attenuation and of inferred attenuation track each other.
• The spectrum content of both beacon attenuation and radiometer data showed components with a frequency of 1 cycle/solar day, 1 cycle/sidereal day and 1 cycle/anti-sidereal day.
• The strength of these peaks varied in each location and is apparently influenced by the climate and path length.

Diurnal variations of received satellite signal in Ka-band, and from co-located radiometer data were investigated using data collected from the propagation measurement campaign conducted by the National Aeronautics and Space Administration (NASA) Advanced Communications Technology Satellite (ACTS). The database contains a maximum of five consecutive years of data collected from seven sites in North America that were receiving signals from a geostationary satellite, using similar on-site equipment and data processing tools. The investigation emphasis is on simultaneous diurnal variation seen in the beacon attenuation as well as attenuation inferred from the co-located radiometer. Evidence showed that the diurnal variations observed on satellite beacon experiments are an atmospheric effect, unconnected with the satellite or the satellite motion. The spectral content of the beacon attenuation data as well as from attenuation inferred from the radiometer showed an element of a solar day periodicity with ‘side-bands’ of sidereal and anti-sidereal periodicities.