Molecular absorption in atmospheric water vapour in
THz frequency band
Kotel'nikov Institute of Radio-engineering and Electronics of
RAS, Fryazino, Moscow region
October 1, 2012
dual-polarized beam-forming network based on a system of coupled dual-mode
metal waveguides of square cross section is considered. Beam-forming network may be used as a
feeding device of a multi-beam mirror or lens antenna. A problem of excitation
of system of coupled waveguides by eigen mode of a waveguide is solved in frame
of approximate theory of coupled waves. An expression describing distribution
of amplitudes of eigen modes at outputs of coupled waveguides is obtained.
Structure of a block of phase shifters correcting phase distribution in output
aperture of the beam-forming network is discussed. A problem of radiation from
beam-forming network is solved with help of physical optics approach.
Dependences of shape of radiation pattern on parameters of the network and
frequency are investigated. It is shown that the analyzed device may form in free space a
system of beams with sector type radiation patterns for waves with two
orthogonal linear polarizations.
Keywords: beam-forming network,
multi-beam antenna, coupled waveguides, dual-mode metal waveguides.