Microwave Path Profile Calculator

Calculate earth bulge, Fresnel clearance, and path viability for microwave links.

Site Parameters

Path Parameters

Enter 0 if no obstacle, or height of terrain/trees at path midpoint

K-Factor Reference

K-Factor Condition Usage
4/3 (1.333)Standard atmosphereNormal design
1.0True earthGeometric reference
0.67Sub-refractionWorst-case clearance
2.0+Super-refractionDucting analysis

Understanding Microwave Path Profiles

Earth Bulge Formula

h = d1 * d2 / (12.74 * K)
where d1, d2 in km, h in meters, K = effective earth radius factor

Earth bulge represents the apparent rise of terrain due to earth curvature. At the midpoint of a path, this is maximum and must be accounted for in clearance calculations.

ITU-R Recommendations

  • ITU-R P.530: Propagation data for terrestrial LOS systems
  • 60% F1: Minimum clearance for diffraction-free path
  • 100% F1: Ideal clearance for zero diffraction loss
  • K=4/3: Standard refractivity gradient (ITU-R P.453)