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Fresnel Zone Clearance

Enter details and press calculate:

Distance (miles):
Frequency (Mhz):
The 1st Fresnel Zone is:
80% of the 1st Fresnel Zone is:
60% of the 1st Fresnel Zone is:

Fresnel Zone:
First Fresnel Zone = 0.305 x (43.3 x Square Root (Distance in Miles ÷ (4 x (Ghz/1000)))
80% of the first Fresnel Zone = 0.305 x (0.8 43.3 x SqRt (Distance in Miles ÷ (4 x (Ghz/1000))))
60% of the first Fresnel Zone = 0.305 x (0.6 43.3 x SqRt (Distance in Miles ÷ (4 x (Ghz/1000))))





Fresnel Zones

Defines how much clearance you need (yes you need more than simple Line-of-Sight) and for longer links > 3 Km (2 miles) whether you may have a ground clearance problem from our friendly planet. M. Fresnel and his theories.

Enter the Total link distance (in Miles or Kilometers), if you do not enter an Obstacle distance (in Miles or Kilometers) the calculator will use the mid-point for all calculations (Note: assumes antennas at same height). Finally enter the system Frequency in MHz and then click the 'Calculate' button. 1 GHz = 1000 MHz e.g. 2400 = 2.4 GHz.

The calculator will generate the radius of the 1st Fresnel zone only (at the obstable point or the mid-point), the 60% (no obstacle) radius and the height of the effective earth curvature at the mid-point of the Total link distance using the effective earth radius.

Calculations and equations used.
Total Link Obstacle Distance 1st Fresnel Zone Radius
 Km
OR
 Miles
 Km
OR
 Miles
 m
at
 Km
 ft
at
 Miles
Frequency   60% No Obstacle Radius
 MHz    m  ft
  Earth Height (mid-point)
     m  ft

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