B.S.T.J. brief: Low-elevation-angle propagation effects on COMSTAR satellite signals

Little information exists on earth-space propagation at lower elevation angles. One earlier experiment1 has shown greater fluctuation in signal levels over low-elevation paths. This signal fluctuation likely results from focusing and defocusing by inhomogeneities in the atmosphere's index of refraction caused by turbulence. The fluctuation increases at lower elevation angles, then, because the signal must pass through more atmosphere. The opportunity existed during 1976 to make more low-elevation observations at 19 GHz as the COMSTAR satellites were placed into position. This paper describes the acquisition and analysis of the low-elevation propagation data. Results are presented showing the fluctuation intensity of the received signal at several elevation angles.