Millimeter-wave atmospheric turbulence measurements: Instrumentation, selected results, and system effects

Abstract

Increasing interest in and greater usage of the millimeter-wave frequency bands has resulted in a need for better characterization of atmospheric effects at these frequencies. While attenuation is recognized as the most significant effect, recent measurements of fluctuations in intensity and phase caused by atmospheric turbulence have shown that these phenomena will also degrade system performance at both millimeter-wave and microwave frequencies. This paper describes the millimeter-wave and meteorological instrumentation used to make these measurements and gives selected results. It is determined that phase fluctuations as great as 1.5 radians and intensity fluctuations as large as 2.8 dB are observed over a 1370 m path in hot, humid weather. The effects of these fluctuations on the performance of practical, existing microwave phased array and monopulse systems are assessed. It is determined that phase fluctuations in particular will degrade the performance of microwave adaptive nulling arrays and monopulse trackers.