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

7-24
Probability (%) > Abscissa
100
9
8
7
6
5
4
3
2
10
9
8
7
6
5
1
4
3
2
1
Propagation Effects for Vehicular and Personal Mobile Satellite Systems
2
0 2 4 6 8 10 12 14 16 18 20 22 24 26 28 30
Fade Depth (dB)
Figure 7-28: Curves labeled 1 and 3 correspond to Category II and curves labeled 4 and
5 represent Category III (defined in text) [Rice et al., 1996]. Curve 2 presented by
Gargione et al. [1995], was derived from measurements over a series of roads that
encircled the Rose Bowl in Pasadena, California.
3
The dashed curve in Figure 7-29 represents a 20 GHz measured distribution obtained for
a tree-lined road in central Maryland in which the deciduous trees were without foliage
and where the tree population was in excess of 55% [Goldhirsh and Vogel, 1995]. This
distribution and others described in Figure 7-30 and Figure 7-31 were derived as part of a
mobile satellite propagation measurements campaign in the United States employing the
Advanced Communications Technology Satellite (ACTS) [Goldhirsh et al, 1995;
Goldhirsh and Vogel, 1994]. The solid curve in Figure 7-29 is the corresponding
distribution assuming the trees along the same road were in full foliage. This distribution
was derived employing a prediction methodology described in Chapter 3. The solid
curve in Figure 7-30 is a 20 GHz distribution at 55° elevation measured in Bastrop, Texas
along an approximate 10 km stretch of road. It was lined with evergreen trees where the
population was in excess of 55% and where there were segments along the road in which
the canopies of trees on both sides of the road formed a tunnel of foliage. The dashed
curve represents the predicted distribution obtained from the EERS model. Figure 7-31
shows a set of distributions measured in the vicinity of Fairbanks, Alaska along tree-line
roads where the elevation angle was 8°. A large variation in the distributions exists
because of the varying likelihood of terrain blockage and/or multiple foliage shadowing
along some of the roads.
4
5