Attenuation diversity measurements at 20 and 30 GHz

The results of data obtained at The University of Texas at Austin in conjunction with the ATS-6 millimeter wave experiment are presented. Attenuation measurements at 30 GHz and sky noise data at 20 GHz were obtained for 93 days simultaneously at each of two sites separated by 11 km and for 314 days at one site. The ratio of the loss at 30 GHz to that at 20 GHz due to rain varied from about 2 to about 4 with a median value of 2.65. This value was used to estimate 30 GHz losses for the 38.6% of time during attenuation events for which the satellite link was not available. Space diversity reduced outage time for a system in Austin, Texas, with a 10 db fade margin at 30 GHz from 3.8 hours to 4.1 minutes for the 93 days. Extrapolated to a yearly base this corresponds to 15 hours and to 16 minutes, respectively. A plot of maximum observed cloud height against maximum hourly attenuation indicates that for a given attenuation level a lower limit is set for the maximum cloud height.