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

4-12
Propagation Effects for Vehicular and Personal Mobile Satellite Systems
Another example showing multipath fade levels at K-Band (18.7 GHz) in a roadside tree
environment, when the satellite was directly in front of or behind the moving vehicle, is
shown in Figure 4-8 as the curve labeled 0° orientation. The other curves in this figure
show distributions for tree lined scenarios in which the orientation of the earth-satellite
path relative to the vehicle direction was 45° and 90°. These curves, also alluded to in
Chapter 7, were derived from measurements in Germany employing a tracking antenna
on a mobile van. This effort was commissioned by the European Space Agency
employing Italsat F1 as the radiating source platform [Joanneum Research, 1995;
Paraboni and Giannone, 1991]. It is clear that the fading for the 0°-orientation case was
primarily due to multipath although some tree shadowing effects may have existed near
the 1% fade level.
Percentage of Time Fade > Abscissa
100
9
8
7
6
5
4
3
2
10
9
8
7
6
5
1
4
3
2
Orientation
45°
90°
0 2 4 6 8 10 12 14 16 18 20 22 24 26 28 30 32 34 36
Fade Depth (dB)
Figure 4-8: Cumulative fade distributions from measurements made in Germany at
18.7 GHz in a tree-shadowed environment at elevation angles 30°-35°. The curve labeled
0° orientation is representative primarily of line-of-sight multipath. The other indicated
orientation angles are the driving azimuths relative to the satellite [Murr et al., 1995].
0°