Fresnel zone

During propagation in space, the radio wave occupies a volume in the form of a rotation ellipsoid with the maximum radius in the middle of the span, called the Fresnel zone. Natural (land, hills, trees) and artificial (buildings, poles) obstacles, entering this space weaken the signal.

Instruction

- Enter the distance and frequency.
- Click "Calculate". The radius of the 1st Fresnel zone at its widest part can be calculated with this calculator. Here d is the link length in kilometers, f is the frequency in GHz, and r - the Fresnel zone radius in meters. * Remarks:

1. Usually blocking 20% of the Fresnel zone introduces negligible attenuation into the channel. Above 40% signal attenuation becomes significant, and obstacles should be avoided in the propagation path.
2. This calculation assumes the earth flat. It does not take into account the curvature of the earth's surface. For extended channels, a comprehensive calculation considering the terrain and natural obstacles in the propagation path should be conducted. For long links, try to increase the antenna suspension height, considering the curvature of the earth's surface.

Distance in Km.	Frequency in GHz
(Kilometers)	(GHz)
First Fresnel zone meters	80% of the first Fresnel zone meters