As times goes by, satellite communication systems demand for higher component integration. Besides, an increase of services is also required, what implies the use of larger bandwidths. To achieve these objectives, the size of microwave devices on the one hand incessantly decreases whereas, at the same time, the power levels increase. Both trends lead to a higher electromagnetic field density inside the components. This development leads to serious problems with respect to RF breakdown (Corona Discharge and Multipactor) caused by high electromagnetic field densities, and cross-talking interference (Passive Intermodulation) due to bandwidth requirements. In this work, Passive Intermodulation (PIM) at waveguide flanges and Corona Discharge in microwave components, e.g. filters, are investigated. In both cases, theoretical research is developed in order to understand the physical mechanisms lying behind both phenomena. Results are presented which are useful for providing particular guidelines to avoid both effects in Sat-Com applications. Systematic experimental research for both phenomena is also presented along the thesis.