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SESK: Stuff Everyone Should Know · sesk.info/ham-ionosphere-fading

What is a likely cause of irregular fading of signals that travel by the ionosphere?

Signals arriving by different paths combining at random.

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  1. Signals arriving by different paths combining at random ✔
  2. Frequency shift caused by Faraday rotation
  3. Interference from thunderstorms

Why: A skywave signal can reach you by several paths at once. As those copies add and cancel at random, the signal fades in and out.

Huh, didn't know that: This is why a distant HF station can go from loud to nearly gone in seconds.

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My HF signal keeps fading in and out. It's not ghosting me, it's just multipath.
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References

Answer: Signals arriving by different paths combining at random. A skywave signal can reach you by several paths at once. As those copies add and cancel at random, the signal fades in and out.

  1. 2026-2030 Technician Class Question Pool, T3A08 ncvec.org/downloads/2026-2030%20Technician%20Pool%20and%20Syllabus%20Public%20Release%20Feb%2019%202026.pdf
    Random combining of signals arriving via different paths
    Checked 2026-10-09.

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