RESULTS FROM 12-GHZ TO 30-GHZ GERMAN PROPAGATION EXPERIMENTS CARRIED OUT WITH RADIOMETERS AND THE OLYMPUS SATELLITE

The rationale for Ka-band propagation studies is discussed and the rel evant measurement program carried out in Germany by the Research Centr e of the Deutsche Bundespost Telekom is reviewed. After a brief presen tation of current problems, this paper addresses the following two maj or topics. (1) Radiometer measurements from a 30-GHz site diversity ex periment. The results indicate that availabilities of 99.99% can be ac hieved with diversity spacings of about 15 km. If however, much lower values of around 97-99% are acceptable, margins of 3dB are sufficient in single site operation with gaseous and cloud absorption being of si milar statistical importance as rain. (2) Measurements carried out wit h the OLYMPUS satellite at 12.5, 20, and 30 GHz. A comparison with the predictions based on the current CCIR procedures shows that rain atte nuation is overestimated for time percentages above 0.01%, while depol arization is underestimated significantly. Instantaneous frequency sca ling of attenuation and scintillations is discussed and an improved sc aling procedure for the latter is presented.