CALCULATING FRESNEL CLEARANCE ZONE

Objects like mountain ridges or buildings close to a radio signal path can affect the quality and strength of the signal. These objects diffract the radio waves which in turn affect the strength of the received signal. Direct visual path (line of sight) is important but it is not enough . The area between receiver and transmitter is known as the "Fresnel Zone" and it must be kept clear of all obstructions. 60% is considered a good Fresnel clearance.