Physics

Fresnel Zone Calculator

Find the radius of the first Fresnel zone of a radio link.

Distance to point 1

Distance to point 2

Frequency (GHz)

Calculated Output

First Fresnel zone radius 17.667

Formula: r = 17.31·√(d₁·d₂ ÷ (f·(d₁+d₂)))

Step-by-Step Breakdown

1. Values used:

2. Distance to point 1 = 5

3. Distance to point 2 = 5

4. Frequency = 2.4 GHz

6. First Fresnel zone radius = 17.667

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The math behind it

r = 17.31·√(d₁·d₂ ÷ (f·(d₁+d₂))) in metres, with distances in km and frequency in GHz.

5 km + 5 km at 2.4 GHz → about 17.7 m radius at midpoint.

How much must stay clear?

Keep at least 60% of the first Fresnel zone unobstructed for a reliable link.