An Earth-Space Propagation Measurement at Crawford Hill Using the 12-GHz CTS Satellite Beacon

This paper describes a measurement of atmospheric attenuation and depolarization, primarily due to rain, of the 11.7-GHz cw beacon signal from the Communications Technology Satellite (CTS). This beacon source made possible the first fixed-path, nearly continuous measurements of earth-space propagation at this frequency. A measurement is being made at Bell Laboratories, Crawford Hill, in Holmdel, New Jersey using a fully steerable, 6-meter-aperture, horn-reflector antenna fitted with a dual-sense, circular-polarized feed. The amplitudes of the copolarized and cross-polarized components are measured with a two-branch, stable, narrowband, frequency tracking receiver. The receiving system, which was designed to run unattended, is described. Propagation data for a greater than 1-year period beginning April 1976 are presented. The attenuation data show that an outage time of 2 1/2 hours per year can be expected for a 10-dB rain fade margin. Significant anomalous depolarization effects not directly related to rainfall have been observed.