Sporadic-E Reflections

The large volume of sporadic-E ionospheric communications logged by Radio Amateurs over the past many years has contributed significantly to understanding the phenomena. There is still more to learn, but many characteristics of sporadic-E communication are now well established. For example, there is a maximum useable frequency (MUF), above which signals are not returned to earth. It may seem counterintuitive at first, but the closer to that frequency one transmits without exceeding it, the further the distance their signal will return to earth via a single sporadic-E reflection. That happens, because the angle of sporadic-E reflection increases as the frequency increases. When the angle increases just to the point where a signal barely returns to earth, it returns at the greatest possible distance. ©2005 Tigertek, Inc. All rights reserved.

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