Adtran TRC6420 Manual Do Utilizador

TRACER 6420 System Manual

Section 2  Microwave Path Engineering Basics

612806420L1-1A

Copyright © 2005 ADTRAN, Inc.

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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

terrain factor

 

climate factor

 

carrier frequency (GHz)

 

path length (miles)

 

fade margin (dB)

The terrain factor is a quantity that compensates the link availability for different types of terrain. 
Generally speaking, the smoother 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:

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 
values normally used are listed below

:

Smooth

4

water, flat desert

Average

1

moderate roughness

Mountainous

1/4

very rough, mountainous

Very Dry

1/8

desert regions

Temperate

1/4

mainland, interior region

Humid

1/2

humid and coastal regions

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