Small Scale Site Diversity for Satellite Communications: 11.5 GHz Propagation Measurements and System Applications

摘要

"Small scale site diversity", a well known antifading technique for satellite communications above 10 GHz, is considered in the paper. This technique takes advantage of the limited extension of heavy rain cells by replacing each earth station in a rainy area with two, or more, interconnected stations and using the earth-satellite path less affected by fading.The statistical results are presented of a three years( 1986-88) propagation experiment. The EUTELSAT-I 11.5 GHz beacon signal rain attenuations on the diversity paths between the satellite and two earth stations located in the Rome area about 16 km apart were measured. The experiment results are synthetically expressed in terms of the "diversity gain", showing that, with an ideal diversity switching system, the fade margin can be reduced by an amount equal to 65-80% of the margin needed in the single station case. On the ground of these results, reasonably extended to a different situation, an example is given of an underdimensioned link which can be made compliant to high availability requirements enabled by the use of the small scale site diversity technique.