B.S.T.J. Briefs: Attenuation Through the Clear Atmosphere at 30, 19, and 13 GHz for Low Elevation Angles

Synchronous satellite service for Alaska, and possibly other places, requires t h a t ground station a n t e n n a s point at low elevation angles. For example, from Point Barrow (71°N, 155°W), such a satellite would never be more t h a n 11 degrees above t h e horizon, and for satellite longitudes 45 degrees east or west of Point Barrow, the elevation is only 5 degrees. At such low angles, the a t t e n u a t i o n of a nominally clear atmosphere is significant in the 18- and 30-GHz b a n d s of proposed domestic satellite systems. There are also satellite bands near 13 GHz, where the a t t e n u a t i o n is expected to be somewhat lower. Predictions of this a t t e n u a t i o n have been made, 1 but as a check direct measurements have been obtained with the Crawford Hill Sun Tracker as reported below.