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What propagation often causes occasional strong signals on 10, 6 and 2 meters from beyond the horizon?

Sporadic E.

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  1. Backscatter
  2. Gray-line propagation
  3. Sporadic E ✔

Why: Sporadic E happens when patches of the ionosphere's E region suddenly get dense enough to reflect higher frequencies. It can bring in surprise long-distance signals.

Huh, didn't know that: Sporadic E openings come and go, which is why the signals are called occasional.

The dad joke
Why is sporadic E so hard to plan for? It never sends a calendar invite.
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References

Answer: Sporadic E. Sporadic E happens when patches of the ionosphere's E region suddenly get dense enough to reflect higher frequencies. It can bring in surprise long-distance signals.

  1. HamStudy 2026-2030 Technician pool, section T3C hamstudy.org/browse/E2_2026/T3C
    Sporadic E
    Checked 2026-10-09.

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