Antenna Height Calculator

Calculate required antenna heights for line-of-sight microwave links.

Link Parameters

Site Elevations

Obstacle Information

Trees, buildings, etc. on top of terrain

Design Parameters

Fresnel Zone Clearance Guide

Clearance Performance Use Case
100% F1OptimalCritical links
60% F1StandardMost applications
30% F1MarginalCost-constrained
<30% F1DegradedNot recommended

Knife-edge diffraction loss increases rapidly below 60% F1 clearance

Antenna Height Formulas

Fresnel Zone Radius

F1 = 17.3 * sqrt(d1 * d2 / (f * d))
d1, d2 = distances to obstacle (km), f = freq (GHz), d = total path (km)

The first Fresnel zone represents the volume where most RF energy propagates. Obstructions in this zone cause significant signal loss.

Earth Bulge

h_bulge = (d1 * d2) / (12.74 * K)
d1, d2 in km, K = effective Earth radius factor
  • K=4/3 is standard atmosphere
  • K=0.67 for worst-case fading
  • Consider both K values in design