Ka-band tracking antenna for inter-orbit communications

The European Space Agency´s Inter-Orbit Communication (IOC) experiment provides a two-way intersatellite link at Ka-band between the low-earth-orbiting European Recoverable Carrier (EURECA) and the geostationary OLYMPUS satellite. Because of the resultant constantly changing link geometry the EURECA IOC antenna must not only provide the 20/30 GHz communication links but also include RF tracking capability within tight volumetric and mass constraints. A novel lightweight tracking antenna, which uses electronically generated higher-order (TE/sub 21/) waveguide modes to scan the main beam, was developed for the IOC antenna, based upon a lower-frequency ground station system. This shaped Cassegrain antenna system, incorporating a novel and compact RF sensing system, has been successfully implemented in flight hardware in an extremely short timescale. The resultant system provides not only the requisite 20/30-GHz communications systems but also a rapid, accurate, and reliable RF sensing capability to permit tracking of the link through the constantly changing orbital geometry with an overall system accuracy significantly better than the 0.5 deg requirement.<>