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

Attenuation Due to Roadside Trees: Mobile Case 3-9
⎛ 80 ⎞
ln⎜
⎟
( , , ) ( 20%,
, )
⎝ P
A P θ f = A θ f
⎠
ln( 4)
(3-13)
Step 4: For path elevation angles in the range 20° > θ ≥ 7°
, the fade distribution is
assumed to have the same value as at θ = 20 ° :
A ( P,
θ , f ) = A(
P,
20°
, f )
(3-14)
In Section 3.7.4, a methodology is outlined for extending the EERS model at L- and
S-Bands to elevation angles greater than 60°.
3.3.4 Example Plots
Applying the above steps, we show plotted in Figure 3-5 to Figure 3-8 a family of curves
describing the cumulative fade distributions at UHF (870 MHz), L-Band (1.5 GHz),
S-Band (3.0 GHz), and K-Band (20 GHz). In Figure 3-9 is given the fade exceeded
versus elevation angle for a family of constant percentages at L Band using (3-7) and the
constants in Table 3-1. These curves may be used for establishing fade-margin design
criteria for LMSS scenarios.
Percent of Distance the Fade > Abscissa
100
10
1
f = 870 MHz
60 55 50 45 40 35 30 25 <
= 20°
0 2 4 6 8 10 12 14 16 18
Fade (dB)
Figure 3-5: Family of cumulative fade distribution curves derived from the extended
empirical roadside shadowing model (EERS) at UHF (870 MHz). The curve labeled
“ ≤ 20deg
” is applicable at angles smaller than 20 degrees as described in the text.