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Compact wide-band coaxial-to-waveguide microwave transitions for X- and Ku-bands


V.A. Rudakov – Post-graduate Student, Southern Federal University. E-mail: V.A. Sledkov – Ph.D. (Phys.-Math.), Leading Research Scientist, Southern Federal University. E-mail: A.P. Mayorov – Head of dept., FGNU NII «Spetsvuzavtomatika» M.B. Manuilov – D.Sc. (Phys.-Math.), Professor, Southern Federal University. E-mail:

A variety of coaxial-to-rectangular waveguide transitions including the right-angle transitions as well as the collinear transitions are used in many microwave applications. However, their disadvantages are narrow operational frequency band or relatively large dimensions and complicated design. To eliminate these disadvantages, a novel compact design of the wide-band right-angle coaxial-to-rectangular waveguide transition has been proposed. The coaxial-to-rectangular waveguide transitions for X-band (8…12 GHz) and Ku-band (12…18 GHz) are studied in the paper. SMA coaxial connector is adopted as an input port. The waveguide ports have standard cross sections 2310 mm (X-band) and 168 mm (Ku-band). The waveguide section is milled in the metal plate in the form of a ridged waveguide to improve the impedance matching. The coaxial line is inserted directly into the waveguide flange. The central coaxial line conductor has got a stepped transition and a cylindrical sleeve, which is positioned on the end of the conductor. The dielectric probe is placed between the ridge and the coaxial probe to fix the coaxial probe. The suggested design of the coaxial-to-waveguide transition has been successfully fabricated for X- and Ku-band operation. The X-band transition shows the measured VSWR less than 1.22 over frequency band 8…12 GHz. The Ku-band transition has measured VSWR less than 1.2 over the band 12…18 GHz. The both transitions have very compact dimensions, which correspond to standard waveguide flanges (424213.6 mm for X-band and 353513.6 mm for Ku-band). A novel design of the compact wide-band coaxial-to-rectangular waveguide transition is proposed, successfully manufactured and tested in X- and Ku-band. The proposed design concept may be implemented in the other frequency bands. The designed transitions were employed for feeding of wide-band horn antennas.


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June 24, 2020
May 29, 2020

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