Fresnel Zone Calculator

Calculate the Fresnel zone radius for a wireless link based on frequency and path distances.

Signal frequency

GHz

Distance from transmitter to point

Distance from point to receiver

Fresnel zone number (n)

Fresnel Zone Clearance

A radio link doesn’t just need a clear line of sight — it needs clearance through an elliptical volume called the Fresnel zone to avoid signal degradation from diffraction and destructive interference. The radius of the n^th Fresnel zone at a point along the path is r = √(nλd₁d₂ / (d₁+d₂)), where λ is the wavelength, and d₁ and d₂ are the distances from that point to each end of the link.

The first Fresnel zone (n=1) is the most important; a common rule of thumb is that at least 60% of the first Fresnel zone radius should remain unobstructed for a reliable link. Higher frequencies produce shorter wavelengths and therefore narrower Fresnel zones, which is one reason higher-frequency links can sometimes tolerate closer obstructions than lower-frequency ones.

Last reviewed August 2026