Keith wrote:
"And do remember, we are discussing the GENERAL case here which includes
transmission lines with complex impedances."

This is a radio amateur antenna newsgroup. The lines used with these
antennas is a special case in which losses in feedlines are usually so
low that Zo does not differ from Ro.

Great simplification results from a surge impedance which equals sq. rt.
L/C.

Many still question what happens in the simplified equivalent circuit of
a lossless line. Once the simplified line action is understood it will
be rewarding to discuss the general case. Keith has repeatedly
demenstrated a desire to treat r-f feedlines as d-c wires. That won`t
work.

Best regards, Richard Harrison, KB5WZI

On Wed, 17 Sep 2003 06:17:54 -0500, Cecil Moore
wrote:

Richard Clark wrote:

wrote:
On what page in Chipman does the Source Z appear relevant?

You referenced equation 7.34.
What do you see appearing in the illustration on the page opposite?

Sorry, I don't see anything. I don't have the book. I drove over to
Texas A&M to see what equation 7.34 really looks like when it is not
forced into ASCII characters.

Then there is no reason to expect you have access to any other page
you asked me for is there? Such is the plight of speed reading.
Everyone selects their favorite passage in ignorance to the whole of
the work.

I have recited enough extractions (including, additionally, my
response to you above) to no refutation. I note that those who asked
for those same examples continue to embrace Chipman despite refusing
to observe his cautions and, frankly, you are less prepared than they
to engage in that discussion much less debate.

The only point of reciting the source is to establish a basis of
common ground. Without that, it devolves to the common sense that the
load and the source are interchangeable and both observe the same
mechanics of reflection that exist as a terminus to a line. Cecil, I
know that you have already stated as much. The quality (sic) of other
discussion that usually attends this issue from more than a few
correspondents, the source somehow deserves some special status where
it magically exhibits no loss, no gain, no reflection, total
reflection, and each-or-all uttered by those who go numb when asked
just what quantitative value enforces such mysterious actions they
purport to occur.

Some suggest it is the imponderability of nature and the cosmos;
others say confusion exists (but not in themselves - even when they
stumble to answer the simplest question); one suggests that methods
and accuracy are in doubt (and cannot say how much error, nor which
method is vague); many say it doesn't matter (and they rage on
demanding just that); and ALL of them cannot answer simple bench
examples that confound their myopic theories.

Such is the kulture of Institutionalized Ignorance that exists.

73's
Richard Clark, KB7QHC

Richard Clark wrote:
The quality (sic) of other
discussion that usually attends this issue from more than a few
correspondents, the source somehow deserves some special status where
it magically exhibits no loss, no gain, no reflection, total
reflection, and each-or-all uttered by those who go numb when asked
just what quantitative value enforces such mysterious actions they
purport to occur.

Easy for you to say. Would you mind diagraming that sentence?

Such is the kulture of Institutionalized Ignorance that exists.

Indubitably.

73 de ac6xg

Richard Clark wrote:

wrote:
Sorry, I don't see anything. I don't have the book. I drove over to
Texas A&M to see what equation 7.34 really looks like when it is not
forced into ASCII characters.

Then there is no reason to expect you have access to any other page
you asked me for is there?

Of course there is, Richard. I just bought a new Harley Road King Classic
and relish any reason to ride it over to the Texas A&M library.

... the source somehow deserves some special status where
it magically exhibits no loss, no gain, no reflection, total
reflection, ...

I agree with you on that point. But there seems to be little
choice except the above due to measurement problems.

Such is the kulture of Institutionalized Ignorance that exists.

I tend to agree but the ignorance is caused by the difficulty in making
meaningful measurements. It's like, "Prove that God doesn't exist."
--
73, Cecil http://www.qsl.net/w5dxp



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On Wed, 17 Sep 2003 13:28:51 -0700, Jim Kelley
wrote:

Easy for you to say. Would you mind diagraming that sentence?

Hi Jim,

Odd that you should ask. In fact I could, and it would be quite easy
except for the restraint of display imposed here. Unlike many of my
cohorts working on their BA English, I took a bonehead class in
sentence analysis and I am still proficient. Consult:
http://www.cybernalysis.com/diagrams/diagrams.htm

73's
Richard Clark, KB7QHC

On Wed, 17 Sep 2003 16:46:23 -0500, Cecil Moore
wrote:

Richard Clark wrote:

wrote:
Sorry, I don't see anything. I don't have the book. I drove over to
Texas A&M to see what equation 7.34 really looks like when it is not
forced into ASCII characters.

Then there is no reason to expect you have access to any other page
you asked me for is there?

Of course there is, Richard. I just bought a new Harley Road King Classic
and relish any reason to ride it over to the Texas A&M library.

Fine, you can start with the illustration offered on the page facing
your referenced equation. You may notice no one here is willing to
give you any help. They act like this is minefield where any mis-step
will make them an amputee candidate in the theory ward.


... the source somehow deserves some special status where
it magically exhibits no loss, no gain, no reflection, total
reflection, ...

I agree with you on that point. But there seems to be little
choice except the above due to measurement problems.

Measurement problems are in direct proportion for those that try to
first calibrate the bone density between their ears. The difficult
part is using simple calipers and a common ruler.

For newcomers it is easily within their skill. Two resistors, a hank
of transmission line, less than an hour's effort and they are done
with unambiguous results. Clearly many, older and slower "students"
here prefer the comfort of ambiguity that so mimics their conditions
of mental constipation.


Such is the kulture of Institutionalized Ignorance that exists.

I tend to agree but the ignorance is caused by the difficulty in making
meaningful measurements. It's like, "Prove that God doesn't exist."

Cecil,

You stand head and shoulders above that crowd of midgets. Hit the
road and prove you can find that page's illustration and I might
suggest several more. Post your query (with proof of reading) from
the student union computers and I will fulfill that offer to save you
time; otherwise find yourself some hog babe along the way, follow the
road out of Texas and enjoy life instead. Choices, choices,
choices....

73's
Richard Clark, KB7QHC

"David Robbins" wrote in message ...
"David Robbins" wrote in message
...

i think the more important thing now is to point out to the arrl the error
of using that form of the reflection coefficient in place of the
'conventional' one in the latest antenna book so it doesn't become gospel
in
the future.


Conventional RC formula is fine, just assume Zo is purely real,
which is what you almost always do anyways.


Slick

"Dr. Slick" wrote:

wrote in message ...

Its not. Its 3.8 volts, which is entirely consistent with circuit
theory and 'classic' rho. Not only is it higher than the incident
voltage, it is higher than the source voltage.

Ok, now take the capacitor off, and measure the voltage at the end
of the inductor. What do you get?

Not possible for me. My scope probes are in the order of 15 pf, which
is signifcant for this experiment.

But try using classic rho and revised rho to predict the results for
a shorted load (Zl = 0). Only classic rho gives a reasonable result
for voltage and current.

And the reflected power can never be greater than the incident.

Classic rho does seem to produce all the proper voltages.
And using the equations implemented in a directional voltmeter,
we get back the expected Vfwd and Vrev.

Using revised rho does not produce the voltages computed with
circuit theory, nor those measured on the bench.
So revised rho does not seem to be the answer to the power
dilemma.

Not really. A rho= -1 means something else with a complex
Zo.

Hint: What is the center of the Smith Chart when it is normalized
to Zo=50+j50?

Let's review. Two competing proposals (classic and revised rho) were
used to predict the outcome of an experiment. The experiment was
performed; the results resoundingly in favour of classic rho.

Are you questioning the scientific method or just the results of
this experiment? If the former, the discussion should probably
move to a different group; if the latter, you are invited to
replicate the experiment and demonstrate that an error was made.

Otherwise, there is no reasonable choice except to accept that
classic rho correctly predicts the reflected voltage.

....Keith

"Dr. Slick" wrote:

"David Robbins" wrote in message ...
"David Robbins" wrote in message
...

i think the more important thing now is to point out to the arrl the error
of using that form of the reflection coefficient in place of the
'conventional' one in the latest antenna book so it doesn't become gospel
in
the future.


Conventional RC formula is fine, just assume Zo is purely real,
which is what you almost always do anyways.

In another branch of this thread it has been demonstrated that the
conventional RC formula correctly predicts the reflected voltage
for lines with non-real Z0. Convential RC is the general predictor
for transmission lines.

The caveat is that for lines with non-real Z0, |rho|^2 can not be
used to predict reflected power. |rho|^2 predicts power only for
the special case of lines with real Z0.

....Keith