Section 2 Microwave Path Engineering Basics
TRACER 6000 Series Split System Manual
26
Copyright © 2005 ADTRAN, Inc.
612806320L1-1B
7.
OTHER CONSIDERATIONS
Path Availability
The path availability of a wireless link is a metric that expresses the fractional amount of time a link is
available over some fixed amount of time, and depends on several factors. Path availability is expressed as
where the parameters are
a
terrain factor
b
climate factor
f
carrier frequency (GHz)
d
path length (miles)
F
fade margin (dB)
or
where the parameters are
a
terrain factor
b
climate factor
f
carrier frequency (GHz)
d
path length (kilometers)
F
fade margin (dB)
Terrain Factor (a)
The terrain factor is a quantity that compensates the link availability for different types of terrain.
Generally speaking, the smoother an area’s terrain, the less availability a wireless link running over that
terrain will have, primarily due to multipath reflections. In contrast, secondary microwave signals will be
randomly dispersed over rough terrain and will not interfere with the main signal lobe as badly as in the
smooth terrain case. The terrain factor values normally used are listed below:
Terrain
Terrain Factor
Description
Smooth
4
water, flat desert
Average
1
moderate roughness
Mountainous
1/4
very rough, mountainous
A
1
2.5
10
6
–
×
(
)
abfd
3
10
F 10
⁄
–
(
)
–
[
]
100%
×
=
(%)
A
1
6.00
10
7
–
×
(
)
abfd
3
10
F 10
⁄
–
(
)
–
[
]
100%
×
=
(%)
