Tower Height & LOS Calculator

Calculate line-of-sight distance and radio horizon.

4/3 is standard for most calculations

Horizon Distance Reference

Height Geometric 4/3 Earth
10 m (33 ft)11.3 km13.0 km
30 m (100 ft)19.6 km22.6 km
50 m (164 ft)25.3 km29.1 km
100 m (328 ft)35.7 km41.2 km
200 m (656 ft)50.5 km58.3 km

Line of Sight Calculations

Radio Horizon Formula

d = sqrt(2 * k * Re * h)
d = distance (km), k = refraction factor, Re = Earth radius (6371 km), h = height (km)

The radio horizon is farther than the optical horizon due to atmospheric refraction bending radio waves around the Earth's curvature.

K-Factor Explained

  • k = 1.0: Geometric (no refraction)
  • k = 4/3: Standard atmosphere (most common)
  • k > 4/3: Super-refractive (ducting possible)
  • k < 1: Sub-refractive (signals curve up)

For reliable links, design for k=4/3 but verify clearance at k=0.67 (worst case).