Excess Loss for High Elevation Angle Links Shadowed by a Single Tree: Measurements and Modeling

Results of experiments focusing on high-elevation links with a ground terminal shadowed by a single tree are introduced. The measurement trials were carried out at 2.0, 3.5, 5.0 and 6.5 GHz utilizing a remote-controlled airship as a pseudo-satellite for four different deciduous trees in summer and winter when trees are in full leaf and defoliated. The complete range of elevation angles typical of satellite/HAP services was addressed. Empirical models were proposed to account for excess loss as a function of its geometry. The applicability of terrestrial vegetation attenuation models on the given scenario is discussed.