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Proceedings Paper

Atmospheric Effects On Target Detection With An Imaging Radiometer
Author(s): T S Chu
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Paper Abstract

The predictions of atmospheric effects on millimeter wave radio imaging of launch vehicles can be obtained by theoretical extrapolation of measured data from propagation studies for millimeter wave satellite communication systems. Attenuation exceedence statistics versus percentage of time have been estimated for both relatively wet and dry temperate climates. Attenuation problems are minimal at 10 GHz, but increase with frequency. Escessive rain attenuation is expected at 30 GHz for a small fraction of time. Cloud attenuation becomes also significant at 100 GHz. Water vapor in clear air can often cause more than 10 dB attenuation at 300 GHz. Using the reciprocity theorem, the effects of angle-of-arrival fluctuations on beam spot resolution have been found to be negligible for a space-based telescope detecting earth-launched vehicles. Beam-coverage area averaging can reduce cloud-induced signal scintillations of several decibels by an order of magnitude. These statements are valid except at very low elevation angles approaching tangent to the earth, where the dominant problem is excessive signal attenuation.

Paper Details

Date Published: 8 April 1988
PDF: 8 pages
Proc. SPIE 0874, Nonlinear Optical Beam Manipulation, Beam Combining, and Atmospheric Propagation, (8 April 1988); doi: 10.1117/12.943859
Show Author Affiliations
T S Chu, AT&T Bell Laboratories (United States)

Published in SPIE Proceedings Vol. 0874:
Nonlinear Optical Beam Manipulation, Beam Combining, and Atmospheric Propagation
Robert A. Fisher, Editor(s)

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