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Tree shadowing is significant for mobile satellite radio propagation investigation and must be known for successful link design. Therefore, there are limited data on the relevant problem. For this purpose, propagation measurements at L and UHF band were performed in Trabzon, Turkey, in 1993 and 1996, respectively. These experiments were executed with a transmitter on the top of a high building, and the receiver system was located in a van outfitted with the antenna on its roof and receiver equipment in its interior. Measurements were carried out for 14 different tree types, and the results of both bands are presented in tabular and graphical forms. Experiments were repeated for the same trees during the months April to September. The variations of the tree attenuation were examined during these months with and without foliage. Average values of the tree attenuations were found to be 8.60 and 11.00 dB for UHF and L band, respectively. The scaling factor between L and UHF band attenuations in decibels was determined to be approximately 1.32. Using these measured parameters, fade depth statistics were calculated using a lognormal shadowing model. To establish validity of obtained results for the design of mobile satellite links, the results were compared with previous investigations.
Date of Publication: Jan 2003