Affiliation: | Norwegian Defence Research Institute, P. O. Box 25, N-2007, Kjeller, Norway Department of Communications and Wave Propagation, Technical University Graz, Inffeldgasse 12, 8010, Graz, Austria Institute for Space Reasearch, Austrian Academy of Sciences, Inffeldgasse 12, 8010, Graz, Austria Swedish Institute of Space Physics, Uppsala Division, S-755 90, Uppsala, Sweden |