Broadband Traveling Wave Tube for Mobile Combined Digital Troposcatter-Radiorelay Station

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Broadband Traveling Wave Tube for Mobile Combined Digital Troposcatter-Radiorelay Station

Journal Title: Цифрові технології - Year 2018, Vol 1, Issue 23

Abstract

Abstract. The article proposes the use of a traveling wave tube (TWT) as an amplifying device of a microwave transmitter for a mobile combined digital troposcatter-radiorelay station (MCDTrRRS). Such a telecommunication system has two separate components - a troposcatter and a radio relay, but a common frequency-shaping system, a control and diagnostic system, and also can have a single microwave transmitter. The radio relay component can operate in various allowed frequency bands, for example in the range 7.9...8.4 GHz. The troposcatter component operates only in the range 4.4...5 GHz. the single microwave transmitter in this case must have a gain band of 4.4...8.4 GHz or operate in the above two frequency bands. The traveling wave tube can operate in this frequency broadband with an output power of more than 1.5 kW without self-excitation on the reverse wave. Therefore, the presence of the TWT makes it possible to realize a single microwave transmitter for the two components of the MCDTrRRS. The entire microwave transmission path is built on a partially filled of dielectric rectangular waveguide (PFDRW). Thus, an increase in the diameter of the helix of TWT at a length equal to 50 ... 60% of the total length of the helix and the introduction of an absorber from the metamaterial significantly improved the output parameters of the instrument over a wide frequency range 4.4 ... 8.4 GHz without self-excitation on the backward wave. It should be noted that the slow wave structure in the form of a helix has a strong structural connection and good alignment with the coaxial-PFDRW-junction (CPFDRW-junction). The coaxial waveguide has a direct connection of the center conductor to the helix. The use of the own function method allowed us to take into account the electromagnetic field in the opening of the coaxial waveguide and obtain the expressions for the CPFDRW-junction in an explicit form. An increase in the broadband of a traveling wave tube is achieved by applying input and output rectangular waveguides partially filled of dielectric, with a simultaneous change in the helix pitch. This solution allows not only to increase the broadband of the traveling wave tube, but also its electrical strength. Such a construction of a traveling wave tube can find application in microwave radio systems, including telecommunication ones, which operate in several frequency bands as it shown on MCDTrRRS example.

Authors and Affiliations

V. N. Pochernyaev, V. S. Povhleb

Keywords

Keywords. a traveling wave tube; partially filled of dielectric rectangular waveguide; coaxial waveguide; CPFDRW-junction; broadband

EP ID EP673995
DOI -
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