Microwave Line-of-Sight Propagation With and Without Frequency Diversity

Amplitude measurements were made for 68 days in 1966 for seven 4-GHz and 6-GHz signals on a typical radio relay path. Identical measurements were also made for one 4-GHz signal on a second path having a common reception point with the first path. We present the results from an analysis centered on the fade-depth distribution for fades exceeding 20 dB. The more significant results are: (i) The fade-depth distribution for all single (nondiversity) channels in a 5–10 percent band on the same path are essentially the same. Further, the distribution has the Rayleigh slope. (ii) The single-channel fade-depth distributions differ for 4 and 6 GHz on the same path; the distributions also differ for the same 4-GHz frequency on adjacent paths with a common reception point. (iii) One-for-one frequency diversity can be characterized during multipath fading periods for either the 4- or 6-GHz bands by the ratio of two quantities. The first is the precent frequency separation between diversity components. The second is the nondiversity fade-depth distribution.