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Introduction. The active development of satellite communication networks determines the need for new antenna systems for ground terminals. The Sphere Federal program implies the commissioning of new satellite constellations for communication and remote sensing of the Earth. The Skif (providing broadband Internet access) and Express-RV (providing the Internet and communications for Arctic) satellite constellations are not geostationary, thus requiring constant satellite tracking even for stationary terminals. Deflecting structures operating on the principle of quasi-optical beam control make it possible to develop scanning antenna systems for organizing continuous satellite communications. Aim. Investigation of various types of dielectric structures for radiation pattern deflection and scanning antenna systems on their basis, as well as identification of a configuration with improved characteristics compared to the ideal structure in the shape of a dielectric wedge. Materials and methods. Mathematical modeling, electrodynamic modeling using CAD by the finite element method and the finite integration method, as well as an experimental study of an antenna system prototype in an anechoicchamber by measuring methods in the far-field and near-field of the antenna. Results. Electrodynamic simulation was carried out for three types of dielectric structures, analogues of a dielectric wedge, including a structure assembled from various dielectrics of fixed sizes with different dielectric constants; a structure of triangular dielectric plates; and a perforated dielectric structure. In addition, scanning antenna systems based on the presented configurations were analyzed. Radiation patterns were obtained for all structural types for various rotation angles of the deflecting systems. The structure assembled from various dielectrics of fixed sizes with different dielectric constants was found to possess the most optimal characteristics. This structure was used to develop a model for experimental confirmation of the conducted electrodynamic simulation. The maximum tilt angle of the radiation pattern was about 60°, the decrease in the directivity relative to the maximum value was 6 dB; for tilt angles up to 55°, the directivity degradation did not exceed 4 dB, the level of the side lobes did not exceed –12 dB (calculated) and –14 dB (measured). Conclusion. The results of studies into various types of structures for quasi-optical beam control of the radiation pattern show the possibility of using these configurations when creating low-profile antenna systems with wide-angle mechanoelectric scanning for organizing satellite communications for both mobile and stationary consumers using medium earth orbit spacecrafts.

Introduction. Duplex satellite communication is commonly arranged using two spaced frequency bands, with one band receiving and the other band transmitting signals to a satellite. The main task of a communications satellite antenna system consists in providing an identical coverage area across all involved frequency bands, which is often a challenging task for conventional parabolic reflector antennas. Reflectarrays allow an independent control of the reradiated wave phase in spaced frequency bands, which can be used to create efficient multi-band antenna systems for modern communication satellites.Aim. To develop a Ka/Q-frequency range phase-correcting element and to create on its basis a dual-band reflectarray for operation with orthogonal circular polarizations and identical gains in a given sector of angles in significantly spaced frequency ranges.Materials and methods. Numerical studies were carried out using the finite element analysis method. Radiation patterns were measured using the near field scanning method.Results. A single-layer dual-band phase-correcting reflectarray element was developed for operation with orthogonal circular polarizations with low losses and a weak dependence of the relative position of the elements on the phase characteristic. On the basis of the proposed element, a reflectarray consisting of 24 465 two-frequency elements was synthesized and manufactured. The developed prototype of a single-layer dual-band reflectarray demonstrated good characteristics, with the efficiency reaching 56 and 36 % in the Ka- and Q-frequency ranges, respectively, and an almost identical minimum gain in the ±0.75° angle sector.Conclusion. The research results confirm the potential of the developed reflectarray to successfully replace conventional parabolic reflectors installed both on modern communication satellites and as part of ground-based satellite terminals in the millimeter wavelength range.