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SESK: Stuff Everyone Should Know · sesk.info/hame-parabolic-gain-doubling

How much does an ideal parabolic dish's gain increase when the operating frequency doubles?

6 dB, which is four times the power gain.

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  1. 3 dB
  2. 2 dB
  3. 6 dB ✔

Why: At a doubled frequency the dish is twice as big in wavelengths, so it focuses a narrower beam. Gain rises with the square of the frequency, which is 6 dB.

Huh, didn't know that: Top loading an electrically short HF vertical improves radiation efficiency (E9D07).

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References

Answer: 6 dB. At a doubled frequency the dish is twice as big in wavelengths, so it focuses a narrower beam. Gain rises with the square of the frequency, which is 6 dB.

  1. NCVEC 2024-2028 Amateur Extra Question Pool, 4th Errata (Feb 4, 2026) ncvec.org/downloads/2024-2028%20Extra%20Class%20Question%20Pool%20and%20Syllabus%20Public%20Release%20with%204th%20Errata%20Feb%204%202026.pdf
    D. 6 dB
    Checked 2026-10-11.

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