Radiometry: A useful prediction tool

A data bank of attenuation statistics at 11.4 GHz, covering 50 site-years of measurements over Western-Europe was established. The information is used as input to studies of the propagation climate of Europe and the world. A statistical model for the relation between annual and average worst-month exceedance is found to give very good results. Practical values for the calculation of worst-month distributions from annual distributions are derived. Fade duration statistics show that only a small fraction of total fading time is due to fades of a duration of 10 sec or less. Therefore, the application of the 10 sec criterion for the distinction between quality and availability requirements has an important impact on the calculation of system margins in satellite communication systems. The diurnal variation of fading is not strong. For practical applications, no dependence on time-of-day should be assumed for the occurence of deep fades.