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Jim Kelley wrote:
I guess one could infer that that if G / C R / L, and R + jwL G + jwC, then perhaps there are losses. I would only add that there are probably also small currents in shunt distributed along the line. If R 0 and G 0, then there are losses. The only time a line is lossless is when R = G = 0 which, according to Reg, is only in my wet dreams about circles on Smith Charts. :-) For real world transmission lines at HF, (usually) R/Z0 G*Z0. When I was a member of the high speed cable group at Intel, I remember test leads designed for R/Z0=G*Z0 but they were expensive special order devices. We apparently are more successful at designing very good dielectrics than in finding an economically feasible conductor with a couple of magnitudes less resistance than copper. Thus our ordinary transmission lines have a lot more series resistance than shunt conductance, especially open-wire transmission lines in free space. :-) -- 73, Cecil http://www.qsl.net/w5dxp |
Gene Fuller wrote:
Do you s'pose that if the equality is perfect for zero-loss lines then maybe it is an useful approximation for low-loss lines? Do you really think R&W were proposing that this simple relationship is more appropriate for low loss lines than for zero loss lines? Nope, exactly the opposite. Apparently, they were proposing that this simple relationship doesn't hold for highly lossy lines. Chipman also has something to say about highly lossy lines. -- 73, Cecil http://www.qsl.net/w5dxp |
Dr. Slick wrote:
Well, that is pretty entertaining and interesting, i will admit. However, the result isn't very practical... On the contrary, the result is extremely practical and isn't very ideal, just like real-world physics. :-) -- 73, Cecil http://www.qsl.net/w5dxp |
Wes Stewart wrote in message . ..
On 23 Nov 2004 07:36:11 -0800, (Dr. Slick) wrote: [snip] | Since i trust Les Besser more than |other people, Heh heh. Reminds me... I took his video taped course, "RF/Microwave Transistor Amplifier Design". I was watching one tape at home while the XYL was making dinner. She could hear the audio and finally asked me to turn it off since it was making *her* fall asleep. [g]. Really smart guy, but not a very dynamic speaker. Hehe! Yeah, also not exactly the sexiest guy on the planet, is he! I have his full RF Fund. course One and Two on tape, like 12 tapes in all. We should have a Les Besser Get together sometime. Wooohaaa! Fun! Slick |
Cecil Moore wrote in message ...
Dr. Slick wrote: Well, that is pretty entertaining and interesting, i will admit. However, the result isn't very practical... On the contrary, the result is extremely practical and isn't very ideal, just like real-world physics. :-) When was the last time you used "G = C * R / L" for anything? Slick |
Dr. Slick wrote:
When was the last time you used "G = C * R / L" for anything? Yesterday. |
Cecil Moore wrote:
Dr. Slick wrote: When was the last time you used "G = C * R / L" for anything? Yesterday. Just curious, Cecil. What were you using a distortionless line for? Tom Donaly, KA6RUH |
Tom Donaly wrote:
Cecil Moore wrote: Dr. Slick wrote: When was the last time you used "G = C * R / L" for anything? Yesterday. Just curious, Cecil. What were you using a distortionless line for? Methinks you jumped to conclusions. Slick didn't ask when was the last time I used a distortionless line. He asked when was the last time I used the equation "G=C*R/L" for anything. I'm using it right now. I used it yesterday to refresh my memory about distortionless lines which I did use quite often before I retired from Intel in 1998. If I presently held a job in the cable modem group, I suppose I would still be using them. -- 73, Cecil http://www.qsl.net/w5dxp |
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