Slant-path attenuation and space-diversity results using 11.6 GHz radiometers

Sky-noise radiometer measurements made at 11.6 GHz at six sites in the Slough area between June 1973 and June 1975 are reported. Single-site statistics are presented which illustrate the variations obtainable between sites within a small geographical area. The time-of-day and time-of-year occurrences of deep fades are given, together with the proportions of events that occurred while the sun was above and below 4° elevation, to show the similarity between ‘night-time’ and ‘daytime’ radiometer results. The large effect that wet snow has on antennas and feeds is discussed. Rainfall-rate measurements are compared with simultaneously recorded attenuation measurements and fade histograms for 3 dB, 5 dB and 7 dB events are presented. The diversity results are given both as cumulative statistics and as diversity advantage against site separation. It is shown that an optimum diversity spacing of around 7 km occurs, provided that the orientation of the diversity baseline is roughly perpendicular to the satellite bearing.