Fresnel Zone Calculator

Your details

Midpoint mode calculates the widest zone radius. Point mode calculates the zone radius at any position along the link. Obstruction mode checks whether a physical obstacle clears the zone.
Carrier frequency of the wireless link in gigahertz. Common values: 2.4 GHz (Wi-Fi), 5 GHz (Wi-Fi/P-P), 900 MHz = 0.9 GHz (SCADA).
GHz
Total distance between the two antennas.
km
The Fresnel zone number to compute. The first zone (n = 1) is the most critical for link planning.
Minimum clearance percentage of the first Fresnel zone. 60% is the common minimum; 80-100% is preferred for critical links.
%
Atmospheric refraction factor. Standard atmosphere = 1.33 (4/3). Use 1.0 for flat-earth (no correction), or a site-specific value.
1st Fresnel zone radius (midpoint)
8.66m

Radius at the widest point (midpoint) of the first Fresnel ellipsoid

1st Fresnel zone radius (midpoint)28.4ft
Nth zone radius (midpoint)8.66m
Minimum clearance required5.19m
Wavelength0.06m

First Fresnel zone radius at midpoint: 8.66 m

  • At 5 GHz over 5 km, the first Fresnel zone reaches 8.7 m in radius at the midpoint.
  • The recommended 60% clearance requires at least 5.2 m of physical clearance from any obstacle at the midpoint.

Next stepSwitch to Obstruction mode to check whether a specific obstacle, such as a building or tree, clears the required Fresnel zone boundary.

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