Millimeter Wave Atmospheric Turbulence Measurements: Preliminary Results And Instrumentation For Future Measurements

Increasing emphasis is being placed on the study of the effects of atmospheric turbulence on the propagation of millimeter and submillimeter waves because of the potential usefulness of these frequency bands in both military and civilian applications. The characterization of millimeter wave turbulence effects is more complicated than that of the optical propagation case because of a strong dependence on the humidity structure parameter CO2, as well as on the temperature structure parameter Gr2. In addition, there is a dependence on the cross-correlation of these two parameters, denoted by CI-0. Measured results on the effects of atmospheric turbulence on millimeter wave propagation, which include both amplitude and phase fluctuations, are very limited and have generally been obtained incidental to other propagation measurements. However, comparison of these limited experimental results with theory has shown good agreement. This paper compares scattered results measured at 35, 94,140, and 220 GHz to theory, and shows that agreement in most cases is plausible. A future experiment specifically designed to characterize millimeter wave turbulence, with special emphasis on measurement of the pertinent atmospheric parameters, is also described.