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RE: Velocity Factor



Hello el bachir

> the length of the radiating inner wire is not just the
> quarter of the wavelenth, but it should be multiplied by the VF(velocity
> factor) constant of the coax cable witch depends on its type. Could anyone
> bring to me more information?

The _radiating_ part can be assumed to have a VF of 100% with the dielectric
around the conductor having a negligible effect. The total dielectric will
include not only the exposed sheath but also the air around it back to earth
and the other half of the dipole - the effect of the air dielectric far
outweighs that of any solid dielectric.

However, a 'shortening factor' of about 95% should be used (varies slightly
depending on how thick your coax 'elements' are), but this is nothing to do
with whether the dipole is made of coax or just wire.

73 Howard G6LVB

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