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The formula for calculating the radius of the first Fresnel zone, as depicted in Figure 21,
is given as:
where,
- D1 and D2 are the distances from the terminals to the point of interest (in
miles), and
- f is the frequency (in GHz)
(Note: multiply results by 0.3048 to obtain a solution in meters)
Figure 21: Fresnel Zone Radius Calculation
Specific FSL formulas are required to deal with this NLOS phenomenon. There are many
NLOS calculations available from established institutions including the Institute of
Electrical and Electronics Engineers (IEEE) and International Telecommunications
Union (ITU), who are chartered with developing standardized calculations. The Redline
Link Budget Tool is built upon these formulas; however, it is important to bear in mind
that the calculations are an estimate only, with relatively large standard deviations (5-15
dB) depending on the exact deployment scenario and obstacle characteristics.
Redline Communications
First
Fresnel
Zone
Figure 20: Fresnel Zone Obstruction
D
* 1
=
R
72
1 .
f
( *
D
Page 68 of 80
AN-30 System User Manual
Obstruction within
first Fresnel Zone
D
2
(ft)
+
1
D
) 2
.....solving the first mile challenge
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