The aim of this project is to investigate the attenuation due to clouds at 20-50GHz; to develop an accurate long-term prediction model of cloud attenuationapplicable to slant-path links and evaluate the impact of cloud attenuationdynamics on the design of future portable EHF earth-space systems. Higherfrequencies offer several advantages, for example, greater bandwidth andimmunity to ionospheric effects. The EHF band is being targeted for the launchof earth-space communication systems to provide global delivery of bandwidthintensiveservices (e.g. interactive HDTV, broadband internet access andmultimedia services, television receive-only, etc.) to portable terminal units.Since spectrum shortage and terminal bulk currently preclude the realization ofthese breakthrough-broadband wireless communication services at lowerfrequencies, a better understanding is needed in order to optimize their usage.One major obstacle in the design of EHF earth-space communication systemsis the large and variable signal attenuation in the lower atmosphere, due to arange of mechanisms including attenuation (and scattering) due to clouds andrain, tropospheric scintillation caused by atmospheric turbulence and variableattenuation by atmospheric gasses. In particular, cloud attenuation becomesvery significant at EHF.In this thesis, we start with an overview of literature review in the first chapter.Followed next by the theory and description of accepted-up to date- cloudattenuation models in the field (chapter 2). Then followed up by a description ofthe pre-processing, validations, sources and assumptions made in order toconduct the analysis of the cloud attenuation in this work (chapter 3).Afterwards, a comprehensive analysis of Meteorological and local troposphericdegradation was carried out (chapter 4). That was followed by an overview ofcloud fade statistics and suggested methods to counter their effects (chapter 5).And finally the improved cloud attenuation model and the enhancement of thecurrently accepted cloud attenuation model (ITU-R 840.4) by terms of validatingthe effective temperature concept and ways of acquiring it (chapter 6).
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