A. D. Drize – Post-graduate Student,

Moscow Aviation Institute (National Research University)

E-mail: temadrize@gmail.com

K. N. Klimov – Dr.Sc. (Eng.), Professor,

Moscow Aviation Institute (National Research University)

E-mail: const0@mail.ru

This article presents the results of numerical electromagnetic simulation of the elements of the microwave waveguide antenna feed: an irradiator, a polarizer and a orthomode transducer (OMT). The feed is supposed to be used with a reflector antenna as a satellite communications ground station operating at the downlink band of 11,7–12,75 GHz and uplink band of 17,3–18,4 GHz in circular polarization.

As part of the design, topological synthesis of the geometry of the devices has been carried out. The irradiator is a corrugated horn with a matching step. The polarizer is made on the basis of a square waveguide with irises. The design of the broadband OMT is based on a turnstile transition.

Numerical electromagnetic simulation has been carried out in the CST Studio Suite program, and the results have been checked in ANSYS HFSS with a Delta S convergence parameter of 0,01. As a result of the simulation, the frequency characteristics of the feed elements have been obtained. The irradiator provides a gain of 10,8 dB, while the VSWR level does not exceed 1,2. The polarizer ellipticity coefficient is 1,08. However, the actual result may differ, because the values from CST and ANSYS programs do not match, and the curve in HFSS is higher.

The selector provides a very low SWR at the outputs (not more than 1,15) with an isolation of more than 60 dB. However, a similar topology based on a turnstile junction is only suitable for in-phase operation. The frequency characteristics of the system as a whole can be worse than calculated due to non-ideal polarization characteristics. Also, the actual characteristics of the devices may differ due to the relative inaccuracy of the simulation and manufacturing errors.

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