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If I want to cut a half wavelength segment of coax for the two-meter band and the velocity factor is 85%, is my cable going to be shorter or longer than a meter?

I'm trying to figure out if the equation should be

  • shorter: $ \text{PhysicalLength}={VF} \cdot \frac{\lambda}{2} $

or

  • longer: $ \text{PhysicalLength}=\frac{\frac{\lambda}{2}}{VF} $

  • or something else?

In my head I seem to think you can fit more wavelengths into a shorter cable if its moving slower than light, but my gut feeling is that is wrong...

This seems like it should be trivial, but I'm twisted around here. If you can explain how I could intuitively understand the meaning of longer or shorter with respect to VF (eg, by analogy) then I would appreciate it!

73

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1 Answer 1

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Shorter. Like you said, the velocity of propagation is lower, which means that the wave travels a shorter distance in the same time, which means that the wavelength is shorter for the same frequency.

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    $\begingroup$ had a brainoutage yesterday; you're right with this answer! $\endgroup$ Apr 15, 2023 at 20:25

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