User guide

Selecting Sites for Network Elements Engineering Your RF Communications
146
pmp-0229 (Mar 2013)
Line of Sight (LOS) Link
In these ranges, a line of sight link is both
• an unobstructed straight line from radio to radio.
• an unobstructed zone surrounding that straight line.
Fresnel Zone Clearance
An unobstructed line of sight is important, but is not the only determinant of adequate placement.
Even where the path has a clear line of sight, obstructions such as terrain, vegetation, metal roofs,
or cars may penetrate the Fresnel zone and cause signal loss. Figure 39 illustrates an ideal Fresnel
zone.
Figure 39: Fresnel zone in line of sight link
Near Line of Sight (nLOS) Link
The 900-MHz and OFDM modules have a greater near line of sight (nLOS) range than modules of
other frequency bands. NLOS range depends on RF considerations such as foliage, topography,
obstructions. A depiction of an nLOS link is shown in Figure 40.
Figure 40: Fresnel zone in near line of sight link