SESKStuff Everyone Should Know
SESK: Stuff Everyone Should Know · sesk.info/hamg-daytime-low-bands

Why is long-distance work on 160, 80, 60 and 40 meters harder in the daytime?

The D region absorbs those signals in daylight.

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  1. The E region is unstable in daylight
  2. The D region absorbs those signals in daylight ✔
  3. The F region absorbs those signals in daylight

Why: Sunlight builds up the D region, and it soaks up lower HF signals. At night the D region fades away, so those bands open for long-distance contacts.

Huh, didn't know that: In summer, the lower HF bands typically have high levels of atmospheric noise or static.

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You know you're a ham when your spouse yells, "Turn off that radio, it's 4 a.m. and I'm trying to sleep!"
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References

Answer: The D region absorbs those signals in daylight. Sunlight builds up the D region, and it soaks up lower HF signals. At night the D region fades away, so those bands open for long-distance contacts.

  1. NCVEC 2023-2027 General Class Pool and Syllabus (6th Errata, Feb 4 2026) ncvec.org/downloads/General%20Class%20Pool%20and%20Syllabus%202023-2027%20Public%20Release%20with%206th%20Errata%20Feb%204%202026.pdf
    The D region absorbs signals at these frequencies during daylight hours
    Checked 2026-10-10.
  2. NCVEC 2023-2027 General Class Pool and Syllabus (6th Errata, Feb 4 2026) ncvec.org/downloads/General%20Class%20Pool%20and%20Syllabus%202023-2027%20Public%20Release%20with%206th%20Errata%20Feb%204%202026.pdf
    High levels of atmospheric noise or static
    Checked 2026-10-10.

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Ham RadioWhich ionospheric region is closest to the Earth's surface?Ham RadioOn which HF bands do General licensees have some off-limits portions?Ham RadioOn which of these bands is voice (phone) operation prohibited?

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