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

7-14
Percentage of Time Fade > Abscissa
100
9
8
7
6
5
4
3
2
10
9
8
7
6
5
1
4
3
2
Propagation Effects for Vehicular and Personal Mobile Satellite Systems
Orientation
0 2 4 6 8 10 12 14 16 18 20 22 24 26 28 30 32 34 36
Fade Depth (dB)
Figure 7-15: Cumulative fade distributions from measurements made in Germany at
18.7 GHz in a tree-shadowed environment at elevation 30° … 35°. The indicated angles
are the driving direction azimuths relative to the satellite [Murr et al., 1995].
7.7 Measurements in Japan
Obara et al. [1993] describe 1.5 GHz land mobile satellite measurements in Japan using
the Japanese ETS-V satellite as the transmitter platform. Employing a tracking antenna
system atop a van, a total distance of approximately 4000 km of primarily expresswaytype
environments was sampled, where the elevation angle ranged between 40° and 50°.
The shadowing environments were comprised of overpasses, tunnels, trees, buildings and
guideposts along the highways. These investigators derived 10 distributions
corresponding to different road measurements. Eliminating the upper and lower fade
extremes of their distributions, Figure 7-16 shows the resulting extreme distributions (of
the remaining eight). The distribution having the smaller fades shows a manifestation of
short period of extreme fades such as may be caused by signal blockage due to tunnels.
45°
90°
0°