Pointing a Ground Antenna at a Circular Orbit Communications Satellite

Two complementary processes of radio antennamain narrow beam pointing to the selected communications satellite are considered: the initial angular beam setting in the direction of the satellite and its beam tracking in order to improve the conditions of radio communication. A rotary support device with control by two angular coordinates: azimuth angle and altitude angle,was chosen as a platform to mount the antenna. At the same time, the rotary support mounting can be carried out both on a resting and on a moving ground platform. The geostationary and low-orbit satellite options were chosen as the communications satellite. As a result, calculation formulae have been obtained and discussed to ensure the following important and frequently encountered in practice modes of ground antennapointing at communications satellites with a circular orbit: setting the angular direction of the ground antenna main beam to a geostationary communications satellite; pointing the transported antenna main beam to the geostationary communication satellite; initial exposure of the angular direction of a stationary ground antenna beam for the acquisition of a low-orbit communications satellite; pointing the main beam of a stationary ground antenna at a moving low-orbit communications satellite; pointing the transported antenna main beam to a low-orbit communications satellite. At the same time, the known dependencies corresponding to the mode of non-guidance of the antenna support and rotary device on the geostationary communications satellite were chosen as the basic mathematical model. The introduction of appropriate substitutions made it possible to be generalized to all other listed pointing modes. The article provides some illustrative calculationsto get an initial idea of the requirements for the pointing system. In general, the disclosure of the articlematerial is carried out from the point of view of a rotary support device developer intereststo implement effective antenna pointing at a communications satellite at the angles of azimuth and altitude.