Comparison among prediction methods of site diversity system performances

Site diversity is a useful countermeasure to overcome severe rain attenuation in satellite communication links. several prediction models of the diversity gain. The authors have tested seven different prediction models of site diversity gain against the results of 47 experiments with various geometrical/radioelectrical system characteristics, at different frequencies from 11 to 30 GHz. Four models have been classified as empirical, the other three as physical models. The average, RMS, and σ of the difference between the estimated and measured percent gain show that the empirical Hodge´s model (see Radio Sci., vol.17, no.6, p.1393-9, 1982). (which was obtained by a best fit over 22 of the 47 experiments here used) behaves better than the others giving the lowest value of σ and a small average underestimate. Nevertheless, two physical models-those of Matricciani´s and Capsoni et al. (see Eur. Trans. Telecom. Relat. Technol., vol.2, no.6, 715-27, 1991; and Radio Sci., vol.22, no.3, p.387-93, 1987, respectively)-which are intrinsically more powerful as they can be also used to predict other propagation quantities, show results very similar to those of Hodge´s that confirm their wide range of applicability