SESK: Stuff Everyone Should Know · sesk.info/hame-half-wave-line-length-14mhz
About how long is an air-insulated parallel conductor line that is electrically a half wavelength at 14.10 MHz?
About 10.6 meters.
- 10.6 meters ✔
- 7.0 meters
- 13.3 meters
Why: A half wavelength at 14.10 MHz is about 10.6 meters in free space. Air-insulated open-wire line has a velocity factor near 1, so the physical length is almost the same.
Huh, didn't know that: Coax is electrically longer than its physical length because waves move more slowly in it than in air (E9F03).
You know you might be a ham when you are two hours late picking up your date because you were working DX on twenty meters.
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References
Answer: 10.6 meters. A half wavelength at 14.10 MHz is about 10.6 meters in free space. Air-insulated open-wire line has a velocity factor near 1, so the physical length is almost the same.
- 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
C. 10.6 meters
Checked 2026-10-11.
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