User`s guide

Radio Signal Propagation
C-9
♦ Interference
Interference may be caused by another system on the same
frequency range, external noise, or some other co-located
system.
The Line of Sight Concept
An optical line of sight exists if an imaginary straight line
can be drawn connecting the antennas on either side of the
link.
Clear Line of Sight
A clear line of sight exists when no physical objects obstruct
viewing one antenna from the location of the other antenna.
A radio wave clear line of sight exists if a defined area
around the optical line of sight (Fresnel Zone) is clear of
obstacles.
Fresnel Zone
The Fresnel zone is the area of a circle around the line of
sight.
The Fresnel Zone is defined as follows:
Figure C-7: Fresnel Zone