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Fresnel Zone & LOS Clearance Simulator

Animated cross-section of a point-to-point link. Shows 1st and 2nd Fresnel zone radii, earth bulge, terrain obstruction, and required antenna height for 60% 1st Fresnel clearance.

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60% 1st Fresnel Zone Clearance — NOT MET

Clearance above obstruction: 7.0 m (32% of 1st Fresnel radius). Increase antenna height or reduce obstruction height.

Frequency Band

Link Distance5 km

Antenna A Height15 m AGL

Antenna B Height15 m AGL

Obstruction Height8 m

Obstruction Position50% from A

Link Analysis

1st Fresnel Radius (midpoint)

21.7 m

60% required ≥ 13.0 m

2nd Fresnel Radius (midpoint)

30.6 m

2nd zone beyond 1st

Earth Bulge (midpoint)

0.25 m

4/3 Earth radius model

Min. Antenna Height (60% clearance)

21.2 m

Above obstruction + bulge

1st Fresnel at Obstruction

21.7 m radius

At 50% along path

LOS Height at Obstruction

15.0 m

Obstruction: 8 m

Clearance Above Obstruction

7.0 m

32% of 1st Fresnel radius

Wavelength (λ)

0.375 m

at 800 MHz

Rule of thumb: 60% 1st Fresnel clearance provides LOS-equivalent propagation. Below 20% causes significant diffraction loss. For obstructed paths, add 6–20 dB knife-edge diffraction loss to your link budget depending on the degree of encroachment.