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

7-8
Percentage of Distance Fade > Abscissa
100
10
1
8
6
4
2
8
6
4
2
Propagation Effects for Vehicular and Personal Mobile Satellite Systems
Terrain Type
Rural/Farmland
Rural/Forested
Suburban
0 2 4 6 8 10 12 14 16 18 20 22
Fade Depth (dB)
Figure 7-6: Cumulative fade distribution at L-Band (1.5 GHz) in Ottawa, Ontario,
Canada obtained from MARECS A satellite measurements in indicated regions at 19°
elevation [Butterworth, 1984a].
7.5 Measurements in England
In Figure 7-7 are cumulative fade distributions obtained in England in typical, rural, tree
shadowed environments where all the trees had full leaf cover [Renduchintala et al.,
1990; Smith et al., 1990]. These results were derived from L-Band transmissions from an
antenna mounted on an aircraft and received by a mobile van. Figure 7-7 depicts the
distributions for a sequence of runs executed at the elevation angles of 40°, 60° and 80°.
As in the case of other investigations, the results demonstrate the strong dependence of
fades on elevation angle.
Smith et al. [1993] report on L- (1.6 GHz) and S-Band (2.6 GHz) measurements of fading
for mobile scenarios at the higher elevation angles also using an aircraft. Measurements
were made for urban, suburban, and tree shadowed environments. Shown in Figure 7-8
and Figure 7-9 are cumulative distributions for tree shadowed environments at L-Band
and S-Band, respectively. This environment was defined as follows:
• Tree Shadowed: “Mature deciduous trees of varying density and distance from the
road. Statistics are for a typical mix of composite cover.”