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One needs to first understand why the 18ft myth started. It is obvious to most that the perception that 1/2 wavelength of 11m (~36ft) is of course 18ft. But their misconception is that the velocity factor of the coax isn't brought into the calculation, as Jazzy George brought up.

If they can see that different kinds of coax have different velocity factors, and then use that factor as a multiplier, they can see that it is often shorter than the measured length of a piece of coax.

Cable Velocity Factor | Velocity of Propagation | Coaxial Cable

[QUOTE="Robb, post: 455153, member: 8446"] One needs to first understand why the 18ft myth started. It is obvious to most that the perception that 1/2 wavelength of 11m (~36ft) is of course 18ft. But their misconception is that the velocity factor of the coax isn't brought into the calculation, as Jazzy George brought up. If they can see that different kinds of coax have different velocity factors, and then use that factor as a multiplier, they can see that it is often shorter than the measured length of a piece of coax. [url=http://www.picwire.com/technical/velocity_factor.php]Cable Velocity Factor | Velocity of Propagation | Coaxial Cable[/url] [/QUOTE]

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