Optimal designs of X-band waveguide stepped-thickness septum polarizer

F. F. Dubrovka; S. I. Piltyay; R. R. Dubrovka; Mykola M. Lytvyn; Sergii M. Lytvyn

doi:10.3103/S0735272721090041

Authors

F. F. Dubrovka National Technical University of Ukraine “Igor Sikorsky Kyiv Polytechnic Institute”, Kyiv, Ukraine https://orcid.org/0000-0002-3485-6822
S. I. Piltyay National Technical University of Ukraine “Igor Sikorsky Kyiv Polytechnic Institute”, Kyiv, Ukraine https://orcid.org/0000-0002-6927-8663
R. R. Dubrovka National Technical University of Ukraine “Igor Sikorsky Kyiv Polytechnic Institute”, Kyiv, Ukraine https://orcid.org/0000-0003-0051-4784
Mykola M. Lytvyn National Technical University of Ukraine “Igor Sikorsky Kyiv Polytechnic Institute”, Kyiv, Ukraine
Sergii M. Lytvyn National Technical University of Ukraine “Igor Sikorsky Kyiv Polytechnic Institute”, Kyiv, Ukraine

DOI:

https://doi.org/10.3103/S0735272721090041

Keywords:

septum polarizer, step-thickness septum, constant-thickness septum, waveguide components, electromagnetic simulation, optimization, feed system, circular polarization, X-band, fractional bandwidth

Abstract

This article presents results of optimization and development of X-band square waveguide stepped-thickness septum polarizers. Electromagnetic characteristics of the polarizers were simulated and optimized numerically using finite elements method. Optimal dimensions of the 2-, 3-, and 4-section stepped-thickness septum polarizers for various fractional bandwidths have been obtained. It is demonstrated that application of the stepped-thickness septum with 3 sections instead of it constant-thickness counterpart improves return loss and cross-polarization discrimination of the septum polarizer by 2–6 dB and 3–6 dB respectively, depending on fractional bandwidth. A prototype of the optimal waveguide polarizer with 3-section stepped-thickness septum configuration for the operating frequency range 7.70–8.50 GHz was developed, manufactured and tested. Measured values of VSWR and cross-polar discrimination of the prototype together with necessary transitions and bends within the stated above frequency range are less than 1.4 and higher than 30 dB, respectively. The developed compact stepped-thickness septum polarizer is a good candidate to be applied in the quasi-monopulse dual-circular polarization feed system of the ground station reflector antenna for tracking earth observing satellites.

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