Radio spectrum the earth (ground waves), shorter waves can reflect off the ionosphere and return to earth beyond the horizon (skywaves), while much shorter wavelengths bend or diffract very little and travel on a line of sight, so their propagation distances are limited to the visual horizon. To prevent interference between different users, the artificial generation and use of radio waves is strictly regulated by law, coordinated by an international body called the International Telecommunications Union (ITU), which defines radio waves as "electromagnetic waves of frequencies arbitrarily lower than 3 000 GHz, propagated in space without artificial guide".[1] The radio spectrum is
Atmospheric-pressure plasma to coat varied surfaces by means of this technique. Thus, anticorrosive layers and adhesion promoter layers can be applied to many metals without the use of solvents and hence in an environmentally friendly manner. Atmospheric-pressure plasma Atmospheric-pressure plasma (or AP plasma or normal pressure plasma) is a plasma in which the pressure approximately matches that of the surrounding atmosphere – the so-called normal pressure. Atmospheric-pressure plasmas have prominent technical significance because in contrast with low-pressure plasma or high-pressure plasma no reaction vessel is needed to ensure the maintenance of a pressure level differing from atmospheric pressure. Accordingly, depending on the