Handbook of Propagation Effects for Vehicular and ... - Courses

3-22
Propagation Effects for Vehicular and Personal Mobile Satellite Systems
Figure 3-21 represents an independent validation of the above foliage formulation for a
set of static measurements at f = 19.6 GHz in Austin, Texas pertaining to a Pecan tree in
full foliage and the same tree devoid of leaves [Vogel and Goldhirsh, 1993a]. The
resulting distributions calculated from measurements correspond to the left and right
solid curves, respectively. The dashed curves represent the predicted levels using the
formulation given by (3-15). That is, the dashed curve on the right is the predicted level
of A(Foliage) where equal probabilities of the measured A(No Foliage) as given by the
left solid curve was injected into (3-15). The left dashed curve represents the predicted
levels of the A(No Foliage), where the measured levels of A(Foliage) as given by the
right solid curve values were injected into (3-15). The formulation (3-15) generally
produces agreement to within 1 dB or smaller over most of the indicated static probability
range.
Percentage of Distance Fade > Abscissa
100
9
8
7
6
5
4
3
2
10
9
8
7
6
5
1
4
3
2
Predicted
No Foliage
Foliage
0 5 10 15 20 25 30 35 40 45
Fade (dB)
Figure 3-21: Independent validation of "no-foliage" versus "foliage" prediction
formulation (3-15) employing static measurements in Austin, Texas at 20 GHz. Solid
curves represent measurements made during different seasons and dashed curves are the
predicted levels.