FM Multi-Path Cancellation

Another effect caused by the line-of-sight characteristics is called cancellation.
- This condition exists when the radio waves are reflected from objects or structures.
- The noise produced by cancellation is similar to flutter, with the addition of distortion in the program.
- A more familiar description of cancellation is its similarity to the multiple ghosts and picture jumping that occurs on television when a low flying plane passes.
- The same condition exists in the vehicle, except that the vehicle is moving and the reflecting structure is stationary.
- The reflected signal cancels the normal signal, causing the antenna to pick up noise and distortion.
- Cancellation effects are most prominent in metropolitan areas, but can also become quite severe in hilly terrain and depressed roadways.