Polarizer for satellite communication systems with polarization multiplexing
Radio engineering. Electronics. Telecommunication systems
Kompany «Radiofizika», 10, Geroev-Panfilovcev Str., Moscow, 125363, Russia
The modern satellite communication systems such as «Yamal-200» and «Express AM3» consist of a set of satellites using the polarization multiplexing in a wide frequency range of C-band. Earth station antennas of such systems should have a level of cross-polarization isolation waves of circular polarization not less than 30 dB in the reception band 3.4 — 4.2 GHz and transfer band 5.75 - 6.55 GHz. Polarizers of antennas for these systems must provide a 90-degree differential phase shift with a deviation of not more than 2-3 degrees, but the lack of higher order modes, the occurrence of which leads to a deterioration of the polarization characteristics. The purpose to the present work is to develop a suitable polarizer for advanced satellite communication systems.
Polarizer consists of a circular 54 mm diameter waveguide and the dielectric plate. Sizing of polarizer elements is carried out by simulation using a computer program based on the solution of Maxwell's equations by the grid method. Dimensions are calculated to required desired approximation accuracy of characteristics and the level of cross-polarization isolation.
The paper presents the design of the polarizer and the results of calculations and measurements of cross-polarization isolation, VSWR for two frequency ranges, and the level of excitation waves higher type.
A prototype of wewideband polarizer for satellite communication systems with polarization multiplexing is developed. It has reduced frequency dependence of the differential phase shift and decreased excitation of higher wave modes.
Keywords:wideband polarizer, satellite communication systems, circular waveguide, dielectric plate, results of calculations and measurements
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