Analysis of mobile-satellite propagation measurements at 18.7 GHz: vegetation effects

Some measurements in the Ka band (at 18.7 GHz) on a land mobile satellite propagation link (ITALSAT 13.2/spl deg/ EST) have been analyzed. These measurements have been performed in surrounding areas of Turin, in the period between February and December 1995, Italy, using the ESA Land Mobile Beacon Terminal (LMBT). ITALSAT is seen from Turin with an elevation angle of 38.7/spl deg/ and an azimuth angle of 172.3/spl deg/; its 18.7 GHz beacon has a reduced coverage, but nevertheless in Turin and with the LMBT instrumentation, the dynamic range of the received signal is approximately 22 dB. The main targets of the work, carried out on sites with only buildings or vegetation, have been the statistical characterization of the Ka mobile channel in different environments (urban, suburban, highway, open areas) by dynamic measurements, and the validation of a geometrical model for vegetation, developed in CSELT, through static measurements. In fact we have evaluated the attenuation due to different vegetation depths by a series of measurements effected with the van parked, in the surroundings of the town: the target of the analysis of these static measurements has been to validate the ITU-R model, at 18.7 GHz, and eventually to give some suggestions for a further improvement. Furthermore, to make easier the study of the measurements and of the causes that generated the attenuation, a Multimedial Analysis of Data System (MAD), that makes it possible to compare simultaneously the radioelectrical parameters and the visual ones taken by two video cameras, has been developed in CSELT.