Rain Fade Attenuation Calculator
Calculate rain-induced attenuation using ITU-R models for microwave and satellite links.
Rain Attenuation vs Frequency
| Frequency | 25 mm/hr | 50 mm/hr | 100 mm/hr |
|---|---|---|---|
| 6 GHz | 0.07 dB/km | 0.17 dB/km | 0.41 dB/km |
| 11 GHz | 0.45 dB/km | 1.1 dB/km | 2.5 dB/km |
| 18 GHz | 1.5 dB/km | 3.3 dB/km | 7.5 dB/km |
| 23 GHz | 2.3 dB/km | 5.0 dB/km | 11 dB/km |
| 38 GHz | 4.5 dB/km | 9.5 dB/km | 20 dB/km |
Approximate values for vertical polarization
ITU-R Rain Fade Model
Specific Attenuation (ITU-R P.838)
gamma = k * R^alpha (dB/km)
where k and alpha depend on frequency and polarization
where k and alpha depend on frequency and polarization
Rain attenuation increases non-linearly with rain rate and frequency. Horizontal polarization experiences higher attenuation than vertical due to raindrop shape.
Path Reduction Factor
r = 1 / (1 + d/d0)
Accounts for non-uniform rain along path
Accounts for non-uniform rain along path
Rain cells have finite extent. Longer paths are less likely to have uniform heavy rain throughout, reducing effective attenuation compared to simple path length multiplication.