Stabilizing the Beams of a Large-Sized Satellite Antenna within the Frame of an Engineering Approach to Antenna Synthesis : (Keynote paper)

Abstract

In my speech, I intend to talk about engineering approach to antenna synthesis and its role in the research that our team conducts for the well known company "Reshetnev Information Satellite Systems".For communication via a geostationary satellite, a plurality of needle-like beams is required to cover the working area within its boundaries. Uneven solar heating distorts the surface of a huge umbrella-reflector, disrupting the required set of beams. In case of multibeam hybrid mirror antennas, cluster adaptive tuning paves the way for beams' stabilization. As the field of the terrestrial beacon, focused by mirror, bears the imprint of the reflector, its current state can be detected from the signals received by the antenna array.The synthesis of the best-fit paraboloid from the signals of a hexagonal cluster is reduced to minimizing the MSD using the concept of shapes' deviation, which we introduced for antenna synthesis. Finding six parameters of the paraboloid from seven (!) signals seems to be a simple task. However, the relationship between the sought-for parameters and the signals is so special that the gradient is oriented almost perpendicularly to the true direction even in the region close to the optimal point. It's amazing how the equipotential surface is shaped like a screw?Reconstruction of the reflector surface without any priori assumptions turned out to be possible within the framework of engineering heuristics, which partially steams from V.N. Dymski’ notion of energetically optimal solution of antenna synthesis. In the area near the reflector, the phase distribution of the field radiated by the antenna array, excited in accordance with the complex conjugate signals from the terrestrial beacon, is compared to the phases of a plane wave propagating towards the beacon. P.V. Romanov, my postgraduate student, raised a sound idea that the points at which the phase difference is constant are the sought reflector points.Evaluation of the consistency and effectiveness of the above approaches requires multivariate calculations. Therefore, the time consumption for modeling a large reflector antenna becomes a decisive factor. We use an extremely fast algorithm based on some robust engineering assumptions that we call acoustic approach.