Rain Fade
The attenuation of a satellite signal caused by precipitation along the signal propagation path, most pronounced at Ku-band frequencies and above.
Full Definition
Rain fade occurs when water droplets in rain, snow, or hail absorb and scatter microwave energy travelling between a satellite and a ground station. The effect intensifies as signal frequency increases, making Ka-band and Q/V-band systems especially vulnerable. Engineers design link budgets with rain fade margins derived from ITU-R rain zone models (e.g., ITU-R P.618). Editors working on technical documents should render the term as two words hyphenated when used attributively ('rain-fade margin', 'rain-fade event') but as two open words when used predicatively ('the signal experienced rain fade'). It should not be conflated with general atmospheric attenuation.
Usage
Usage note: Hyphenate when used attributively ('rain-fade margin'); leave open when used as a noun ('the link experienced rain fade'). Not interchangeable with the broader term 'atmospheric attenuation'.
In Context
- "The Ka-band terminal's rain-fade margin of 8 dB was validated against ITU-R P.618 predictions for the site's rain zone." — Link Budget Report
- "Operators recorded a 12-minute rain fade outage during the tropical storm, reducing availability below the contracted SLA threshold." — Incident Report