Coherent pulse transmission through rain

The problem of received signal degradation for coherent pulse transmission through a rain scattering volume was investigated for large bandwidth transmission at 4.0, 8.0, 15.5, and 34.86 GHz. Calculations of pulse length and total pulse energy were made for different path lengths through the rain volume. The calculations were made for models of heavy and extreme rainfall, using rain rates 49.0 and 196.3 mm/h. The results of the computations show that for the rain rates considered, the dominant cause of signal degradation is attenuation. Negligible pulse lengthening was noted at 34.86 GHz. For rain rates above 196 mm/h and frequencies of 15.5 and 8.0 GHz, measurable values of pulse lengthening were calculated for bandwidths above 2.0 GHz. At 4.0 GHz, measurable values of pulse lengthening were obtained for both rain rates considered.