Time efficient antenna & payload measurement technique for future multi-spot-beam antennas

Future communication satellites equipped with multi spot beam antennas are providing more than 100 adjacent coverages on earth create very high demands for RF measurements during acceptance test campaigns performed prior to the satellite´s launch. The antenna´s beam isolation and frequency re-use capability require high measurement accuracies for the related test facility and a high time efficiency during the antenna and payload test campaigns considering the high number of beams. This paper explains in detail the measurement system concept and control of multi-port antenna measurement set-ups working on a time-multiplex concept which provides typically a higher beam-to-beam isolation and higher measurement accuracies than alternative concepts working on low frequency modulated scatterer technique. Since future satellites will make also use of Ka frequency bands, traditionally used PIN switches are not favorable due to the increasing insertion loss at those frequencies. For that reason an alternative approach was designed by utilizing MEMS switches. Additionally the paper points out the attainable time efficiency for typical spacecraft antenna measurements in compact range test facilities using state-of-the-art equipment with a few adaptations for dedicated telecommunication applications, e.g. the above mentioned MEMS switches.