Check this out:
http://jwatrous.org/swtl.pdf
Note that this is the basis of a specific commercial product and there are other people using similar technology for power line defect monitoring. The papers associated with all these show similar results.
Yeah, not exactly a direct parallel, but it’s Saturday and I’m working for free.
Ahh, because?
There are measurements.
There’s discussion of the effects of surface corrosion.
There’s comparison with Sommerfeld-Goubau transmission lines.
(Nothing at all to do with Chip Cohen and his fractal antennas, though)
What issues are being obfuscated? With long single wire lines, the transmission loss is due to either radiation or resistive losses. Or both, of course.
I've read that article and can find no discussion of surface corrosion just the sentence
which hardly tells us much.
Jeez, sorry!
I guess you actually need to go through the material covered by the footnotes and read the theory. I bet that Google thing might have some clues.
For what it's worth - I have old prototype boards at work with IFA style cellular antennas on them, they were made with immersion silver finish and they are now heavily oxidized (actually, they were pretty ugly within a week). They went through carrier compliance testing when new and shiny. They were retested at some point a few months later and the radiated power and isotropic sensitivity figures were nearly identical, within the test setup margin of error.
Microwaves101 | Surface Roughness
I thought it was common knowledge that surface roughness causes increasing loss with increasing frequency.
There are special coaxial cables where the center conductor is silver plated.
Scott I realize you ignored the depth of .003" that I mentioned. That is pretty deep. A very heavy silver plate would be half that typical could be a few percent. Also note silver that is tarnished does not have reduced resistance. Also the tests were on cable directivity not wire.
Just for reference when laying out sheet metal by hand a skilled worker can get accuracy of .005". So that order of surface defects should be visible.
I thought it was common knowledge that surface roughness causes increasing loss with increasing frequency.
There are special coaxial cables where the center conductor is silver plated.
Scott I realize you ignored the depth of .003" that I mentioned. That is pretty deep. A very heavy silver plate would be half that typical could be a few percent. Also note silver that is tarnished does not have reduced resistance. Also the tests were on cable directivity not wire.
Just for reference when laying out sheet metal by hand a skilled worker can get accuracy of .005". So that order of surface defects should be visible.
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Not very special ones. It's very common. Silver plated copper coated steel core is used in common or garden RG214 to name but one.
You said uniform layer of a 1000 times less conductive material how this translates to a roughness in a fully conductive material only you know. Also this is audio not microwaves and you seem to ignore the magnetic properties of the coating which matters to skin depth. There are studies on line of accelerated life tests on power transmission lines with gross corrosion in acid baths.
Silver plating of cavities etc. is well know to increase Q, so we have silver (higher conductivity) with lower loss, bare copper the basic loss, a coating of copper oxide, 1/1000 conductivity, 1.2dB/ft, a coating of Teflon (0 conductivity) puts us where?
If you don't show the formulation you are working from and the assumptions you make there is no point in a discussion. The basic theory here is a bunch of one liners, it's not that hard to present them.
No that is not what I wrote.
I use this construct know as paragraphs as the direction of information changes.
The bit describing a commercial approach to cables contained my estimate that .003" would be needed to be useful filtering an audio cable. I did not mention the type of plating.
Next was the consideration of normal copper wire oxidation. I can't imagine that occurring to a depth of .003". The point was that surface defects could leave spots of deeper and non-uniform oxide inclusions.
I had previously mentioned I found no issues with mistreated wires expected to have a significant increase in fractures. What has not been tested is if the increase in fractures oxidize over time and causes measurable changes.
Y’know, I get your point.
I just somehow misplaced my silver platter sometime in the last week.
I’ll know better next time. Again, sorry.
Saying such doesn't make it true. Everybody knows that, especially you.
I contribute a lot, especially with E/M, soldering, epoxies, and building hardware, coils, magnets, that kind of stuff. I provide lots of info using experience from high energy physics, production line military weapons, satellite, undersea cable, medical, telemetry...
And I do it because I won't be here forever, none of us will. I want the next generation to carry on this stuff. EXACTLY the way you would like the next generation to continue the analog expertise we both see as missing in the current education.
What you call "criticism", I consider well grounded in fact. Making up or passing on completely unfounded and inaccurate speculation about magic technology does not educate the next generation. I will always resist the ridiculous. Your recent "stuff" on e/m microscope thingies was so easily trashed by reading the actual pages, that does not build your credibility, it only lowers it.. That is why I stated you should stick to what you know, you are so good at it...
Even now, I am trying to teach the young controls guys how to control multi-ton objects to the single digit nanometer level during high acceleration and velocities of a mm/sec.....they have no idea what a bode plot is, what phase margin is, how to stabilize a negative feedback system with 6th order response, how to design an adaptive feedback system...THE EXACT TECHNOLOGY THAT YOU ARE AN EXPERT IN!!! Well, most of it anyway. I have the luxury of being able to design feedback systems which can adapt gain, feedforward, and integration to changing phase margin, dynamic springiness, shifting masses, non orthogonal axis...you know, the simple stuff...audio cannot do that in a timely fashion. My biggest problem is, I have to trade off complexity of the system to do the task with the controls peoples ability to understand what I did. 23 years ago, I never considered that, so I still am the only one who understands the system I built then.... Now, I'm a little more seasoned..(and yes, I shower every day so it's not that kind of seasoned...)
I value your expertise...in what you are good at. That is what I would like to see from you. There are so many young guys out there that need your expertise, please figure out how to pass it on..
I am doing that through working groups, seminars, lectures, and presentations I give freely to other national labs.. what are you doing to pass on knowledge?
jn
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Bill,
As somewhere around 27% of the planet is wired with coax for television and these days to a lesser extent telephone and other stuff, most of that coax is not silver plated. So I suspect although silver plated cable is easily available it is still special.
(Yes I made up the 27%!)
JN,
I hired a fellow with a BSEE who couldn't do Ohm's law calculations correctly. I mentioned this to a friend who taught at his alma mater. He looked into it and saw how he managed to get a degree bypassing the basic courses. He made sure it won't happen again.
Now I have to check and see if Bode is still in the required course track.
Now being my not so subtle self, JJ mentioned his local college didn't require calculus until the senior year. I had a bit of trouble believing this until I ran into a pair of graduates who confirmed that, but mentioned most folks took it in their junior year to get it out of the way.
I hired a fellow with a BSEE who couldn't do Ohm's law calculations correctly. I mentioned this to a friend who taught at his alma mater. He looked into it and saw how he managed to get a degree bypassing the basic courses. He made sure it won't happen again.
Now I have to check and see if Bode is still in the required course track.
Now being my not so subtle self, JJ mentioned his local college didn't require calculus until the senior year. I had a bit of trouble believing this until I ran into a pair of graduates who confirmed that, but mentioned most folks took it in their junior year to get it out of the way.
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