I know that fading can be caused by phase rotation of the arriving signal. Can fading be caused by the signal changing arrival angle over time (1-3 seconds)? I ask this because of something I observed while attempting to tune my Shared Apex Loop (SAL) antenna the other night.
In the forward direction I tuned in a strong, distant AM broadcast signal that was fairly steady strength-wise. It would vary less than an S unit as seen on my radio S-meter (FTdx5000). Then I switched to the reverse direction. From the SAL backside the signal experienced rapid fading from S0 to S8. Looking at the elevation pattern of the SAL (or just about any RX antenna design) it can be seen that the forward direction has a broad gain pattern around the 20 degree arrival angle. In the reverse direction there is a deep steep null near that reverse angle. From this I assumed that the signal was changing arrival angle, moving into and out of that deep null. Is this the correct analysis? Kris N5KM _________________ Topband Reflector Archives - http://www.contesting.com/_topband