Fresnel Zone Calculator

Calculate Fresnel zone clearance radius for wireless link design. Includes earth curvature bulge and minimum antenna height.

Frequency

MHz

Link Distance

Obstacle Position Along Path

Tab to move between fields

1st Fresnel Zone Radius

12.5 m

60% Clearance (Min.)

7.5 m

Min Clearance Height

7.87 m

2nd Fresnel Zone Radius17.67 m

3rd Fresnel Zone Radius21.64 m

Max Radius (at Midpoint)12.5 m

Earth Curvature Bulge0.37 m

Wavelength0.1249 m

How to Use This Calculator

Enter link frequency (MHz) and total link distance (km).
Set the obstacle position along the path as a fraction of total distance (0.0 to 1.0).
Review the 1st, 2nd, and 3rd Fresnel zone radii at the obstacle location.
Ensure 60% of the 1st Fresnel zone is clear of obstacles for a clean line-of-sight link.
Use required clearance height to specify tower heights or choose alternate path routing.

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Formula

r = √(n × λ × d₁ × d₂ / D)

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