Statistical Investigation of the Effect of the Troposphere on Millimeter-Wavelength Radiation and Coherence

摘要

The coherence properties of radio propagation through the troposphere at millimeter-wave frequencies were statistically analyzed to obtain a description of the medium. Experimental data, obtained at a 39-GHz frequency over an 18-mile radio link, included analog and digital recordings of demodulated r-f signals received by two antennas that were separated vertically. A very thorough statistical analysis of these data was made. Moments and probability distributions of the received signal amplitude were determined by experimentation. The fit of these distributions to theoretical curves was measured and found to be good. Other analyses that were performed included the computation of autocorrelation functions and corresponding spectral densities and cross-correlation functions and cross-spectral densities in both space-time and frequency. The coherence and other statistical properties of the received signals were measured in space as well as in time, and the effect of the medium on these properties was analyzed. The most important result was the significant decorrelation observed in the vertical plane between the amplitude fluctuations of the signal outputs of the two antennas, particularly under windy weather conditions. (Author)