Line-of-Sight Propagation Phenomena-I. Ray Treatment

The effect of variations in index of refraction on line-of-sight propagation of electromagnetic waves in the troposphere is investigated using, in this paper, a ray theory approach. Mean-square variations in phase delay and phase correlation between two paths are calculated. It is shown that these quantities are relatively insensitive to the form of space correlation function assumed for the index of refraction. The mean-square phase is proportional to ¿N2l0 where l0 is scale length and ¿N2 the mean-square variation in index of refraction, whereas in beyond line-of-sight propagation the received power is proportional to ¿N2/l0. Variations in angle of arrival are also calculated and it is shown that here the assumed space correlation of index of refraction is critical in determining the angle of arrival characteristics. It is shown, however, that a certain portion of the angle-of-arrival spectrum is insensitive to the choice.