This thesis investigates statistical correlation as a means to enhance the use of ground-based radar in analyzing satellite-path millimeter wave propagation through rain and ice crystals. The technique presented involves correlating dB values of the satellite signal attenuation and polarization isolation with dBZ values of radar backscatter from each of 128 range gates. In it, Pearson product moment correlation coefficients are calculated for attenuation and backscatter and for isolation and backscatter. When these coefficients are plotted versus radar range, one of four certain characteristic patterns usually appears. Ice-crystal depolarization produces a pattern of near zero attenuation coefficients and varying isolation coefficients. Rain produces a correlation pattern in which the attenuation coefficient pattern is nearly mirror image of the isolation coefficient pattern. A special case of the rain event occurs when the cross-polarized satellite signal is essentially constant. The correlation patterns for this case are exact mirror images. Rain attenuation and depolarization accompanied by additional depolarization from another source, produce a correlation pattern that is not symmetrical. This is due to the additional depolarization. Discussion of these expected patterns and examples of each are presented. / Master of Science

The instantaneous performance of a site diversity system is analyzed. This analysis is performed using instantaneous diversity gain (a new parameter for describing diversity performance) and the correlation coefficient. Also, a relationship between the correlation coefficient and instantaneous diversity gain was established. In addition, a review of statistical diversity gain and existing models of statistical diversity gain were also presented. Measured statistical diversity gain data from the VPI&SU site diversity experiment were also presented and compared with instantaneous diversity gain. The relationship between the correlation coefficient and instantaneous diversity gain was used to present a crude model of diversity gain. This model was compared with the model of Hodge. Margin calculations were performed to display the usefulness of instantaneous diversity gain. These were performed using the VPI&SU site diversity experiment data. / Master of Science

Dual polarization allows a communication system to transfer twice as much information as a single polarized communication system, with no increase in the required bandwidth. Site diversity may be used in high frequency satellite communication systems to reduce the effects of attenuation and depolarization due to rain and ice. This thesis examines dual polarized site diversity satellite communication systems to determine how such systems would perform under operating conditions. Three diversity system models, including a new model which incorporates local weather patterns, are discussed and compared. The problem of how to select the best signals from the available diversity replicas is investigated for both PSK and FM modulation schemes. A new technique is proposed for combining the effects of attenuation. and isolation into a single criterion for FM systems. The thesis considers methods for improving dual polarized site diversity system performance. Compensation schemes, coherent signal addition, and optimum site location are investigated. A compensation scheme using pilot tones is proposed. Finally, the performance of operational PSK and FM systems is simulated using data from a VPI & SU satellite beacon experiment. / M.S.