The primary purpose of this thesis is to present, in clear and logical form, an analysis of high-frequency modulation. This will be done in order to explain each of the various methods of obtaining modulation, and the characteristics of the resultant waves. The question of side bands will be considered in detail. The subject of circuits and associated apparatus is of secondary importance, emphasis being placed on the fundamental electric theory. From this point of view, possibilities for improvement and new developments will be investigated. / Master of Science