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no, I am not guessing.

CJ: ""Making a sweeping criticism without pin-pointing the issue will not help. Besides, how is one so sure the questions are even justiable basing on self assumed 'facts' or simply on one's speculation or assumption. Make sure one can substanatiate its criticism or remarks against anything allegedly incorrect.""
You discussed the prop velocity and how we can hear the differences but yet do not have the ability to measure it.

You were therefore asked, how?

It is a simple and logical question which arises from your statement. So, logically, it is a justifiable question.

CJ: ""BTW, this wire & cable fundamental is taken out from a paper published by a leading cable manufacaturer in the USA. I take nothing for granted.""
Unfortunately, what you have done is taken out of context, what appears to be correct information, and incorrectly applied it to the topic at hand.

I explain..

The information you provided is the determination of velocity of propagation for a fully formed e/m wave (TE, TM, and TEM), unconstrained by any physical barriers.

The equation of course, being υ = c/√ (ε μ)

You have cut and pasted information from a site which only considers the variation of ε without regard to μ. So they are only considering the propagation through an isotropic medium with μ equal to that of free space.

That is not how most wires (transmission lines) work.

The ONLY transmission line which has the ability to transfer a signal at the free space velocity of the dielectric is a coaxial line. The coaxial line constrains the magnetic field via external cancellation, and confines the E field within the dieleictric. For all other cases, the velocity of propagation is reduced by the lack of control of the external fields. Zip cables, for example, create a dipole field externally, so does not use the dielectric solely, but uses also the external space around the pair, that being free space.

Note that this use of external space with it's DC of 1, does not mean that the prop velocity will increase. In point of fact, it causes the velocity to decrease.

The equation for any cable is:

υ = c/√ (LC)

Further bounds:

LC = 1034 * εr (for coax)

L in nH per foot, C in pf per foot

LC = 1034 * εeffective for all other cases,

εeffective being the geometrically determined effective εr..I am keeping this simple by ignoring the effective μ, which is really how the unconstrained magnetic field system operates..

If your source thinks otherwise, I will be happy to correct them..


Cheers, John



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