2 ence of a wave zone or induction zone under industrial and exper- imental conditions determines the physical values used to assess the intensity of irradiation (the power flux density or the field in- tensity), the instruments used for measuring, and the experimental technique (irradiation from a distant source, in a cavity resonator, inductor, capacitor, and so on). The physical parameters eVidently also determine the biolog- ical effects of the different frequency bands. In recent decades various bands of radio waves have been extensively used in many branches of industry. The microwave band has been widely applied in the field of radar, radionavigation, radioastronomy, radiometeorology, radiocommunication, nuclear physics, and physiotherapy. The short-wave and ultrashort-wave band are used for physiotherapy, radiocommunication, broadcast- ing, television, and also for the heat treatment of dielectrics and for welding plasticized rubber. The long and medium waves are used for the heat treatment of metals in the vacuum-tube industry and in mechanical engineering.
