Plain-language answer: Fading is time- or position-varying received strength caused by propagation, multipath, polarization, absorption, motion, or changing noise.
Why it changes the path
It can affect one station, one frequency, or one signal component differently and does not necessarily indicate hardware instability.
What to observe
Log time, band, path, movement, weather, and multiple signals before changing the antenna.
The common mistake
Retuning the station during every short propagation fade.
Planning boundary
Propagation models and field regions depend on frequency, geometry, terrain, atmosphere, polarization, antenna pattern, and measurement distance. Use them to plan and compare—not to guarantee a contact or installed range.
