B.S.T.J. Briefs: A Three-Radiometer Path-Diversity Experiment

01 July 1970

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A Three-Radiometer Path-Diversity Experiment By R. W. WILSON (Manuscript received February 27, 1970) Data from the Crawford Hill sun tracker have confirmed the expectation that frequencies above about 10 GHz experience large attenuations on an earth-space path when heavy rain is encountered.1 Tillotson has proposed using frequencies of about 20 and 30 GHz for a domestic communication satellite system." In that case, the required continuity of service would be achieved by using two or more diversity ground stations. The three-radiometer path-diversity experiment discussed here was designed to work in conjunction with the sun tracker to determine the advantage of diversity ground station pairs at these frequencies. A common method of measuring atmospheric attenuation on earthspace paths at microwave frequencies has been to measure the brightness temperature of the atmosphere. In the absence of scattering, one can obtain the attenuation in a path through the atmosphere from the relationship between the physical temperature (T), attenuation (A), and brightness temperature (T b ). (1)