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Molecular absorption in atmospheric water vapour in 0-1 THz frequency band


.Yu. Zrazhevsky and S.V. Titov

Kotel'nikov Institute of Radio-engineering and Electronics of RAS, Fryazino, Moscow region

Received October
1, 2012

Abstract: Two-dimensional 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.