Reg Edwards wrote:
Write it down. It will then be obvious, to make the angle of Zo equal to
zero it is necessary only that the angle of R+j*Omega*L be made equal to the
angle of G+j*Omega*C.

Reg, there is no contradiction between what I have said and what you have said.

Continuing the discussion - For average transmission lines used on HF
frequencies, "... the value of G ... is likely to be too small to affect the
attenuation factor ..." Quote from "Transmission Lines" by Chipman, page 94.

Some of Chipman's calculations indicate that, for a typical 10 MHz example,
R is about 0.1 ohm/meter while G is about 0.9 micromhos/meter. That's about
a 100,000:1 ratio making G negligible as far as attenuation factor goes.

The attenuation factor depends almost entirely on R, the series resistance
parameter. G, the parallel conductance parameter, has a negligible effect
on the attenuation factor at HF.

Since, at HF, the attenuation factor consists almost entirely of series
resistance, and since the attenuation factor is identical for voltage and
current, it logically follows that the series resistance is primarily
responsible for the attenuation of the current.

Or even more simple, for Zo to be purely resistive, G = C*R/L

Actually, that is only an approximation for low-loss lines.
--
73, Cecil, W5DXP

Cec, I was well aware of what Chipman was about to write years before he
wrote his most excellent, most reliable book on the subject of transmission
lines. There are are very few errors. All of those which I have found can be
attributed to the printer. But you don't find these unless you actually use
the book, fully understand the book, and do some practical sums.

There are far too many people who use books as bibles because they have
found them verbally convincing but who have never actually used them by
inserting practical engineering numbers. No-one unfamiliar with numbers can
call himself an engineer. More likely he is a plagiarising Old Wife.

I do not worship Chipman. I think he is still plodding around in his 90's. I
don't worship anybody.

Whilst on the subject of reliability, I have very recently had a serious
accident.

My corkscrew broke.

It can only have been due to metal fatigue and all the use its had.
Probably made in Taiwan or Korea.

For 5 days, for one reason or another, I have been confined to the house
without the opportunity to replace corkscrews. Yet there have been 4
unopened bottles of perfectly good wine in the cooler, with clean glasses.
Calamity! Absolute misery!

But my long mechanical engineering experience came to the rescue. I
discovered a 1/4" Philips screwdriver and a hammer. With lots of hammering I
eventually drove the cork (of a bottle of Premieres Cotes de Bordeaux,
sweet-white), inside the bottle.

The cork floats on the top of the wine and there's few problems with
pouring. The cork remains quite intact. No contaminating bits to spit out.

So everything is now back to normal. I shortly expect to obtain a new
corkscrew - this time with a spare.

Hic!
----
Reg.



"Cecil Moore" wrote in message
...
Reg Edwards wrote:
Write it down. It will then be obvious, to make the angle of Zo equal
to
zero it is necessary only that the angle of R+j*Omega*L be made equal to
the
angle of G+j*Omega*C.

Reg, there is no contradiction between what I have said and what you have
said.

Continuing the discussion - For average transmission lines used on HF
frequencies, "... the value of G ... is likely to be too small to affect
the
attenuation factor ..." Quote from "Transmission Lines" by Chipman, page
94.

Some of Chipman's calculations indicate that, for a typical 10 MHz
example,
R is about 0.1 ohm/meter while G is about 0.9 micromhos/meter. That's
about
a 100,000:1 ratio making G negligible as far as attenuation factor goes.

The attenuation factor depends almost entirely on R, the series resistance
parameter. G, the parallel conductance parameter, has a negligible effect
on the attenuation factor at HF.

Since, at HF, the attenuation factor consists almost entirely of series
resistance, and since the attenuation factor is identical for voltage and
current, it logically follows that the series resistance is primarily
responsible for the attenuation of the current.

Or even more simple, for Zo to be purely resistive, G = C*R/L

Actually, that is only an approximation for low-loss lines.
--
73, Cecil, W5DXP

Reg Edwards wrote:
There are far too many people who use books as bibles ...

Ain't that the truth? I post "1+1=2" and somebody wants a reference.
I just bought "Mathematics From the Birth of Numbers" by Jan Gullberg.
In addition to information on virtually all branches of mathematics,
it gives the history of the branches. It's really interesting.

With lots of hammering I
eventually drove the cork (of a bottle of Premieres Cotes de Bordeaux,
sweet-white), inside the bottle.

At the beer/wine busts at Texas A&M during the 50's, nobody
could ever remember to bring a corkscrew so that's the way
we did it. Sometimes we forgot a bottle opener and used the
bumper of my old '49 Chevvy to open the beer.
--
73, Cecil, http://www.qsl.net/w5dxp