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

3-24
Percentage of Distance Fade > Abscissa
100
9
8
7
6
5
4
3
2
10
9
8
7
6
5
1
4
3
2
March, 1986
Propagation Effects for Vehicular and Personal Mobile Satellite Systems
October, 1985
0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16
Fade Depth (dB)
Figure 3-22: Cumulative fade distributions at L-Band (1.5 GHz) in central-Maryland
during various seasons.
3.6 Frequency Scaling Considerations
The frequency scaling formulation applied to the ERS model is applicable between UHF
(870 MHz) and S-Band (3 GHz) and is given by
for 1% ≤ P ≤ 30% and 870 MHz ≤ f ≤ 3 GHz :
f
A f A fL
dB
f
) ( ) ( = , (3-20)
L
where fL = 1.
5 GHz and where A ( f ) is the attenuation expressed in dB at the frequency
f (expressed in GHz). The frequency scaling in the EERS model is given by exponent
factor in (3-1).
Figure 3-23 depicts a comparison using both frequency scaling formulations and the
measurements of Bundrock and Harvey [1988]. The open circled points correspond to
the formulation (3-20) and the solid points represent the formulation (3-1) with A( f L)
corresponding to the L-Band frequency (1.55 GHz) and attenuation values of Bundrock
and Harvey. That is, the estimated points shown were derived from the middle curve
corresponding to the L-Band measured distribution. Since both scaling methods give
approximately similar results, it is suggested that (3-1) be used for simplicity over the