ADTRAN 4206 Plan A Other Considerations, Path Availability, Terrain Terrain Factor Description

TRACER 4106/4206 System Manual Section 2 Microwave Path Engineering Basics

Table 5. Minimum Antenna Height for Given Path Lengths (Continued)

Path Length	Min. Antenna Height	Min. Antenna Height
	@ 2.4 GHz	@ 5.8 GHz
(miles)
	(ft)	(ft)
28	220	177
30	239	195
32	259	213
34	279	232
36	300	252

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

A = [1 – (2.5 ⋅ 10–6)abfd3(10–F⁄10)] ⋅ 100% (%)

where the parameters are

aterrain factor

bclimate factor

fcarrier frequency (GHz)

d path length (miles)

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 more smooth an area's terrain is, 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

Climate Factor (b)

The climate factor is a quantity that compensates the link availability for different types of climates (weather). In general, microwave links operating in areas with high humidity will have less availability than those in arid areas, primarily because water is a dispersive mechanism to microwave energy, and causes the main signal lobe to refract and disperse away from the receiver location. The climate factor

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