Scattering of Millimeter Waves in Line-of-sight Propagation

Résumé du livre

Line-of-sight propagation measurements at 34.89 GHz and 11.63 GHz on a 28 km path are analyzed with particular emphasis on (a) transmissable bandwith and (b) the effects of rain. Bandwidth studies are approached by measuring the frequency covariance of the 3:1 frequency ratio employed, and then using the theory of weak scattering to infer the covariance of signal fluctuations at lesser frequency separations. The conclusions reached from this approach indicate negligible bandwith limitations for bandwidths of a few per cent (300-400 MHz, at 35 GHz), as a consequence of single scattering processes; i.e., the inferred frequency covariance between extremes in the band should exceed 0.95. The effects of rain, while showing up markedly in attenuation at the higher frequency, do not have other consistently deleterious consequences. Angle-of-arrival jitter is relatively unaffected. Frequency covariance is more erratic during squally weather but tends to rise during times of heavy rain.