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UBC Theses and Dissertations

Rain attenuation at 74 Ghz McNicol, John Duncan


A millimetric wave transmission link of the radar type has been established at the University of British Columbia campus. It operates at 74 GHz and has a 1.8 km total transmission length. The RF source is an unmodulated klystron and a phase-locked receiver is used to detect the received signal. The main objective is to measure the excess path attenuation due to precipitation. For this purpose a weather station has been constructed. It consists of 5 tipping-bucket rain gauges distributed along the path and apparatus for the measurement of temperature and wind velocity. The level of the microwave signal and the outputs of the weather sensors are transmitted to a central station. There, initial processing and data recording on magnetic tape are performed on a continuous basis by a Nova 840 minicomputer. Subsequently, data is further processed on an IBM 370. Of the 1400 hours of data recorded during a four month period, approximately 25 hours included simultaneous rain and microwave data and were sufficiently "reliable" to analyse. The processed experimental data are compared with the theory of Ryde and Ryde over the range of rain rates observed (0 to 10 mm/hour).

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