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Author Topic: 90 degree adapters lossy -- why?  (Read 1009 times)

Lee Buckalew

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Re: 90 degree adapters lossy -- why?
« Reply #20 on: September 14, 2018, 10:52:02 am »

Dave's original response did not refer to c, it referred to the speed of light in copper, which I clearly understood to be the speed of the wave in the medium.

I can see how it could be read that way although it could also be read as referencing both RF and analogue audio transmission through copper to "the speed of light" which is commonly used to refer to the speed of light in a vacuum.
Technically, I think they both move at the speed of light through copper.
The RF just wiggles a lot faster.


I was not trying to argue here, just trying to clarify so that those reading understood the difference between "the speed of light" as commonly used and "the speed of light transmitted through copper".

Hopefully this thread has been able to clarify what certainly appeared to be confusion at points.

So, yes, the basic understanding is that electricity travels through copper at the same velocity that light travels through copper. 
Neither electricity nor light travel through copper at the commonly understood reference of "the speed of light" which would be the speed of light in a vacuum or "c".

Lee
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Jason Glass

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Re: 90 degree adapters lossy -- why?
« Reply #21 on: September 15, 2018, 03:16:26 pm »

As if the physics of a signal passing through a cable aren't complicated enough, here's yet another concept to consider.

At audio frequencies, an alternating current passes through almost the entire diameter of the conductor and radiates very little at mic and line voltages.  At radio frequencies, signals pass only through the outermost portion of the center conductor diameter due to skin effect and radiate, reflecting back and forth between the outside diameter of the center conductor and the inside diameter of the shield, passing through the dielectric material of the coaxial cable, down the cable's entire length.  The velocity factor of said cable is the percentage of the speed of light through copper that the dielectric material imparts on the signal.

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« Last Edit: September 15, 2018, 03:20:52 pm by Jason Glass »
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Ike Zimbel

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Re: 90 degree adapters lossy -- why?
« Reply #22 on: September 18, 2018, 12:43:27 am »

As if the physics of a signal passing through a cable aren't complicated enough, here's yet another concept to consider.

At audio frequencies, an alternating current passes through almost the entire diameter of the conductor and radiates very little at mic and line voltages.  At radio frequencies, signals pass only through the outermost portion of the center conductor diameter due to skin effect and radiate, reflecting back and forth between the outside diameter of the center conductor and the inside diameter of the shield, passing through the dielectric material of the coaxial cable, down the cable's entire length.  The velocity factor of said cable is the percentage of the speed of light through copper that the dielectric material imparts on the signal.

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And, to bring all of this back to the OP. RF cable is designed to have the distance between the conductor, dielectric, and shield be as consistent as possible. With a 90 degree connector, this means that the conductor inside would have to be be bent very, very precisely to maintain a consistent distance to the outer walls of the connector. I think it's a safe bet that that level of precision manufacturing is not going to be present in a cheap connector from Amazon.
« Last Edit: September 20, 2018, 12:18:33 pm by Ike Zimbel »
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