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

3-26
and where
1
2
Propagation Effects for Vehicular and Personal Mobile Satellite Systems
2
M ( θ ) = a1θ
+ a2θ
+ a3
, (3-22)
2
N(
θ ) = bθ
+ b θ + b
a
a
a
b
b
b
1
2
3
1
2
3
= 1117 . Χ10
= −0.
0701
= 61304 .
= 0. 0032
= −0.
6612
= 37. 8581
−4
3
(3-23)
In the above, A( θ, P)
is the L-Band (1.5 GHz) fade in dB, P is the percentage of fade
exceeded applicable in the range 1% to 30%, and θ is the elevation angle (in degrees)
valid from 20° to 80°. In Figure 3-24, the above MERS formulation is compared with the
EERS model at 30°, 45°, and 60°. The two models at the different angles generally agree
with one another to approximately 1 dB at the equal percentage levels. The 60° MERS
distribution appears shifted to the right relative to the EERS model by approximately
1 dB. Although the above formulation is described for L-Band, it may be used for
S-Band frequencies applying the frequency scaling relation (3-20) [Butt et al., 1995].
Percentage of the Time Fade > Abscissa
100
9
8
7
6
5
4
3
2
10
9
8
7
6
5
1
4
3
2
60°
45°
30°
0 2 4 6 8 10 12 14 16 18 20 22 24
Fade Depth (dB)
Figure 3-24: Comparison of EERS model (solid) with MERS (dashed) results at L-Band
(1.5 GHz).