Statistical Analysis of Rain Fade Slope

Abstract—An analysis is made of the measured distributions of the fade slope of rain attenuation, conditional for attenuation values, measured at Eindhoven University of Technology from the satellite Olympus. It is found that the distribution is similar for positive and negative fade slopes and independent of frequency in the range from 12 to 30 GHz. A distribution model for the condi-tional distribution is found. The only parameter of the distribution is the standard deviation, which is found to be proportional to at-tenuation level and dependent on rain type, on the low-pass filter bandwidth and on the time interval used in the slope calculation. The observed relation between the standard deviation and attenu-ation is compared with results from other measurement sites. From this comparison it is found that the fade slope standard deviation is likely to depend on elevation angle and on climate, through its dependence on rain type. Index Terms—Adaptive fade countermeasures, fade slope, mi-crowave propagation, rain, rain attenuation, satellite communica-tions, up-link power control. I