S.V. Polenga - Senior Lecturer, Siberian Federal University (Krasnoyarsk) E-mail: twinlive@gmail.com A.M. Alexandrin - Senior Lecturer, Siberian Federal University (Krasnoyarsk) E-mail: aalexandrin@sfu-kras Yu.P. Salomatov - Ph.D. (Eng.), Professor, Head of Department, Siberian Federal University (Krasnoyarsk) E-mail: ysalomatov@sfu-kras.ru K.V. Lemberg - Ph.D. (Phys.-Math.), Associate Professor, Siberian Federal University (Krasnoyarsk) E-mail: jivako@gmail.com A.A. Popovich - Deputy General Director, JSC «SPE «Radiosviaz» (Krasnoyarsk) E-mail: a.a.popovich@yandex.ru

This work presents the results of the development and experimental study of a combined horn feed designed for using in the satellite earth stations. The feed operates at two frequency bands: Ka-band (29,5-30 GHz, HF) with circular polarization for transmitting and Ku-band (10,7-10,95 GHz and 12,5-12,75 GHz, LF) with linear polarization for receiving. The feed is the coaxial combination of axially corrugated horn for Ku-band and dielectric rod antenna made from PTFE for Ka-band. The orthomode transducer provides the separation of high and low frequency parts of the operating band. The operation of high frequency part with circular polarization is provided by a polarizer placed within the round HF-waveguide. The polarization can be switched from right to left by turning the polarizer by 90° manually. The entry of HF-energy into LF-port is prevented by the means of the corrugated filter placed at the outer side of HF-waveguide near its radiating end. The polarizer used in the feed represents a segment of the round waveguide with two parallel truncations of its walls. The experimental prototype of the feed was constructed and measured. The feed has two waveguide ports: WR-75 for Ku-band and WR-28 for Ka-band. The VSWR is lower than 1,5 in Ku-band and lower than 1,2 in Ka-band. The isolation between ports reached 55 dB, the calculated value being 70 dB. The differences between calculated and experimental values are due to manufacturing errors since the filter has high sensitivity to the manufacturing accuracy. The measurements showed that feed-s -10 dB beamwidths differ not more than by 5°, the phase center displacement is not more than 16 mm in Ku-band and lower than 3 mm in Ka-band, cross-polarization isolation is more than 30 dB. The developed feed can be used in commercial VSAT terminals.

 

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