📡 Radar Horizon Calculator
Find the maximum radar line-of-sight distance based on antenna and target height.
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Radar Line-of-Sight Horizon
The radar horizon is the maximum distance at which a radar can detect a target due to the curvature of the Earth, accounting for the slight downward bending of radio waves caused by atmospheric refraction. It’s commonly estimated using d (km) = 4.12 × (√h1 + √h2), with heights h1 and h2 in meters for the radar antenna and target respectively.
The constant 4.12 (instead of the pure optical value of about 3.57) accounts for the standard “4/3 Earth radius” approximation used in radio propagation, which models the atmosphere’s typical bending of radar waves. Actual range also depends on radar power, target size, and atmospheric conditions.
Last reviewed August 2026