ULTRA-LIGHTWEIGHT 20m ANTENNA REFLECTOR AND LIGHT-WEIGHT 100 BEAM CLASS FEED SYSTEM FOR FUTURE MOBILE BROADBAND COMMUNICATIONS SATELLITES

摘要

Lowering the costs and increasing the performance of commercial satellite systems requires larger and lighter antennas. We've been investigating two key technologies. The first one is an ultra light-weight large antenna reflector whose aperture diameter is larger than 20m and whose areal density is less than 0.25 kg/m~2. Target total mass is 130 kg including a boom structure and holding/release structures. Our proposal is a reflector antenna that uses a geodesic cable network structure supported by a tendon structure. Prior studies using a conceptual model showed that such antenna reflectors appear feasible. The second is a light weight multi-beam antenna feed system. The feed system consists of 64 radiation elements, variable phase-shifter, and beam forming network. The feed system can form 69 beams, whose RF power can be controlled to matching the corresponding traffic conditions by overlapping beam groups. Beam pointing errors and defocuses can be corrected by using the phase-shifter connected to feed elements. These antenna configurations can effectively reduce total mass of a satellite system with keeping electrical performances.