A Comparison of Measure and Calculated Frequency Correlation Functions over 4.6- and 7.6-GHz Troposcatter Paths

The results of an extended series of propagation measurements to determine the envelope frequency correlation coefficients at 4.6 and 7.6 GHz over four paths ranging from 140 to 200 km are reported. Comparison is made with previous experimental findings and with the models of Rice [6], Sunde [9], and Bello et al. [11]. The correlation coefficients measured simultaneously at the two frequencies were found nearly equivalent although a marked time dependence was evident over periods as short as 30 min. A discussion is given of the several expressions that have been referred to as envelope correlation functions, a distinction that is necessary when comparing the results of various workers and empirical models. An attempt is made to modify the empirical parameters entering the models to agree best with the experimental findings.