Plain-language answer: Multipath occurs when copies of a signal arrive by different routes, such as direct, reflected, diffracted, or ionospheric paths.
Why it changes the path
Different delay and phase can reinforce, cancel, distort, or rapidly change the received signal as frequency or position moves.
What to observe
Move the antenna slightly, change polarization or frequency, and compare signal plus decoding quality to identify path sensitivity.
The common mistake
Blaming every deep fade on transmitter power or antenna failure.
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.
