New techniques for predicting the multipath fading distribution on VHF/UHF/SHF terrestrial line-of-sight links in Canada

Abstract

New methods are presented for predicting the signal fading distribution due to multipath propagation for the average worst month on VHF/UHF/SHF terrestrial line-of-sight lines in Canada. One method for the deep fading range does not require detailed path profile information and is designed for preliminary planning or licensing purposes. A second method which does employ the path profile is intended for more detailed design purposes. A third method, complementary to the other two, is given for predicting the distribution in the shallow fading range. All three methods are presented in step-by-step form for ease of application. The detailed bases of the methods, and their relationship to earlier methods, are also presented. These methods are the first to employ refractivity gradient statistics in the predictions and to cover the VHF/UHF bands in addition to the SHF band. Some guidance is also given to the designer on the path clearances required to minimize the effects of multipath fading.