Measurements of s.h.f. tropospheric fading along Earth-space paths at low elevation angles

Measurements have been made at Ottawa, Canada of the amplitude fluctuations which occur when s.h.f. signals are propagated through the troposphere at low elevation angles. At a frequency of 7.3 GHz, it was found that, for elevation angles below 3°, fades greater than 6 dB and 10 dB occurred in the winter and summer months, respectively, for 0.1% of the time.