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

Attenuation Due to Roadside Trees: Mobile Case 3-17
distribution at K-Band (dashed curve). We observe that the EERS distribution deviates
from the adjusted measured distribution by less than 5 dB.
The red dot-dashed curve in Figure 3-15 was derived from previous L-Band
helicopter measurements in June 1987 [Goldhirsh and Vogel, 1989] employing the
following procedures: (1) Distributions were examined which corresponded to the same
scenario as for the K-Band measurements; namely, the vehicle was traveling in the
southwest direction and the helicopter was on the left, (2) a resultant 39° distribution was
derived by interpolating the 45° and the 30° distributions at L-Band, and (3) the L-Band
distribution was extended to K-Band employing the frequency scaling factor given by the
exponential term in (3-1). We note that relatively close agreement exists between the
adjusted distribution (based on helicopter measurements; dot-dashed curve), the foliage
adjusted ACTS distribution (right solid curve), and the EERS model (dashed curve)
[Goldhirsh and Vogel, 1995a; 1995b].
Percentage of Distance Fade > Abscissa
100
9
8
7
6
5
4
3
2
10
9
8
7
6
5
1
4
3
2
ACTS Meas. (No Foliage)
ACTS (Foliage Scaled)
Helo Meas. (Freq. Scaled)
EERS
0 5 10 15 20 25 30 35 40 45
Fade Depth (dB)
Figure 3-15: Plots of K-Band (20 GHz) cumulative fade distributions from measurements
in central Maryland at elevation angle of 39°.