Extremely high frequency paths. They are not reflected by the ionosphere nor do they travel along the Earth as ground waves as lower frequency radio waves do. At typical power densities they are blocked by building walls and suffer significant attenuation passing through foliage. Absorption by atmospheric gases is a significant factor throughout the band and increases with frequency. However, it is maximum at a few specific absorption lines, mainly those of oxygen at 60 GHz and water vapor at 24 GHz and 184 GHz. At frequencies in the "windows" between these absorption peaks, millimeter waves have much less atmospheric attenuation and greater
Atmospheric-pressure plasma earth potential and in this way largely holds back potential-carrying parts of the plasma stream. In addition, it determines the geometry of the emergent beam. Based on transistor amplifiers up to 200W power RF (radio frequency) and microwave sources are used to generate a microwave plasma. Most of the solutions work at 2.45 GHz. Meanwhile, is a technology developed which provide the ignition on the one hand and the high efficient operation on the other hand with the same electronic and couple network. This kind of atmospheric-pressure plasmas is different. The plasma is only top of the electrode. That is