SESKStuff Everyone Should Know
SESK: Stuff Everyone Should Know · sesk.info/hamg-g9a06

In what units is RF feed line loss usually expressed?

Decibels per 100 feet.

Start playing free

  1. Decibels per 100 feet ✔
  2. Ohms per 1,000 feet
  3. Decibels per 1,000 feet

Why: Feed line loss is a power ratio, so it is given in decibels. The standard length used is 100 feet, not 1,000 feet.

Huh, didn't know that: Higher loss in a feed line reduces the SWR measured at the input to the line.

The dad joke
Feed line loss is billed by the hundred feet, with no volume discount.
Like this card?
Play the game

References

Answer: Decibels per 100 feet. Feed line loss is a power ratio, so it is given in decibels. The standard length used is 100 feet, not 1,000 feet.

  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
    D. Decibels per 100 feet
    Checked 2026-10-11.
  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
    Higher loss reduces SWR measured at the input to the line
    Checked 2026-10-11.

Think this answer is wrong? Tap "Challenge this answer" on the card in the game and tell us why.

Test yourself in the game

Ham RadioWhat percentage of power is lost when a circuit has a 1 dB loss?Ham RadioAbout how many dB represents a factor of two increase or decrease in power?Ham RadioWhat is the nominal characteristic impedance of window line transmission line?

That's stuff everyone should know.