Airborne satellite antenna mount and tracking systems

Communication mobile satellite antennas (MSA) are relatively large and heavy, especially airborne high gain antenna (HGA) systems for Inmarsat-H and HSD aircraft Earth stations (AES). Over the past decade, steering airborne antenna systems, which comprise a mechanical assembly, a control electronic system, a microwave electronic package and an antenna assembly (arrays and steering elements), have reduced considerably in physical size and weight. These reductions, brought about by greater EIRP from satellite transponders coupled with GaAs-FET technology at the receiver front end leading to higher G/N RF amplifiers, have initially made the fitting of shipborne antennas on trucks and airplanes a reality. A little later, airborne and vehicle-borne MSA were developed on the basis of these shipborne antennas. The MSA systems are required to be always pointed towards the satellite, in spite of vehicle motion. Therefore, the mount system is one of the main requirements, from the technical and rational viewpoints, in designing MSA systems. Several types of mount system are used, including mechanical and electrical among others, especially those concerned with shipborne MSA systems. In the case of airborne and vehicle-borne MSA, electrical pointing systems are preferable.