Millimeter-wave beams in ground-based telecommunication systems

The amplitude and phase of a millimeter-wave beam are investigated in the transition (Fresnel) zone lying between the geometrical-optic and the far-field (wave) zones. The investigations are carried out with the use of the angular spectrum of the complex amplitude of a field over a bounded opening of a parabolic antenna and the angular frequency characteristic of free space of an unperturbed atmosphere in the Fresnel (quasioptical) approximation. Relations and estimates for the energy potentials of transceivers for atmospheric radio links of visual-range telecommunication systems are obtained with regard to the radiation patterns of the elementary area of a Huygens source and transmitting and receiving antennas in the wave and Fresnel zones, as well as in the zone of deep geometrical shadow cast by a half-plane and in the region of scattering by turbulent inhomogeneities of the dielectric permittivity of a cloudless atmosphere. The necessary transmitter power and receiver sensitivity are determined for such atmospheric radio links.