User's Manual

Table Of Contents
Installation Planning 25
Where:
Fl = First Fresnel zone radius in meters
d1= Distance from transmitter to reflection point in kilometers
D = Length of direct signal path in kilometers
d2 = D - d1
f = Transmission frequency in GHz.
Figure 3-1 shows that the Fresnel zone radius is greatest at midpath. It is at this point that the
required obstacle clearance is greatest. The equation given previously yields the 0.6F1
minimum beam clearance envelope values at midpath as shown in Table 3-1. Also use the
equation to calculate the necessary minimum beam clearance envelope for other obstacles
along the path, especially near both endpoints of the path.
Figure 3-1 Fresnel Zone Clearance
Direct Path
.6F1 Envelope
d1
d2
IW100201
0.6F1 10.4
d1d2
fD
------------ Fresnel Zone Clearance formula=