Radio Links and Antennas in Boundless or Bounded Lossy Media

摘要

The report is divided into three parts. The first part deals with the definition of suitable simple, clear and distance invariant parameters, apt to describe the radiation and reception of electromagnetic fields into boundless or bounded lossy media, as well as with the computation of the radio link formula in various situations (e. g., the far, intermediate and near field range in sub-surface or underwater propagation). The second part deals with the computation of the above parameters for linear electric bare antennas with a sinusoidal current distribution of complex argument. The above parameters are referred under several graphs. The most interesting result is that the efficiency of a bare antenna may reach relatively high values (e.g. from 20% up to 40%), provided that the length of the antenna is of the order of the wavelength into the lossy medium. The third part deals with a new type of antenna, particularly suitable for applications in lossy media, and realized by means of two closely spaced parallel plates, whose gap is filled by an insulator. The plates act as current collectors. Some preliminary experiment on model and real parallel plate antennas are referred. (Author)