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SESK: Stuff Everyone Should Know · sesk.info/hame-fresnel-zone-smallest

Which of these frequency bands has the smallest first Fresnel zone?

5.8 GHz, the highest frequency listed.

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  1. 2.4 GHz
  2. 900 MHz
  3. 5.8 GHz ✔

Why: The Fresnel zone gets narrower as the frequency goes up and the wavelength gets shorter. So the highest band here needs the least clearance around the path.

Huh, didn't know that: Soil conductivity determines ground losses for a ground-mounted HF vertical (E9A11).

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References

Answer: 5.8 GHz. The Fresnel zone gets narrower as the frequency goes up and the wavelength gets shorter. So the highest band here needs the least clearance around the path.

  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
    A. 5.8 GHz
    Checked 2026-10-11.

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