On Thu, 28 Aug 2003 06:27:40 GMT, "George, W5YR"
wrote:

... "Theory and Problems of Transmission Lines" by
Robert A. Chipman. This is a Schaum's Outline book - mine is dated 1968.
Many professionals acknowledge that this is one of the most succinct and
revealing accounts of t-line theory to be found. Mathematical enough to be
rigorous but readable and highly useful.


Hi George,

I have notice you recommended this author several times, and yet you
have casually dismissed his rather straightforward coverage relating
to the characteristic Z of a Transmitter:
There is no need to know, since its value, whatever it might be, plays no
role in the design and implementation of the external portion of the system
driven by the transmitter.

How do you reconcile this with his coverage entitled
"9.10. Return loss, reflection loss, and transmission loss."

You may wish to observe the clearly marked figure 9-26 and
specifically the paragraph that follows (or the entire section for
that matter) that quite clearly reveals what is everywhere else
implied: that ALL SWR discussion presumes a Zc matched source. You
may observe that Chapman thus refutes your statement above. Further,
Chapman goes to some length to describe the Smith Chart's appended
line evaluation scales at the bottom to this very matter.

To substantiate this from other sources I have offered a very simple
example that shows this importance that to date has defied "first
principle" analysis (not first principles however, merely the claim of
its being practiced analytically in this regard). I will offer it
again, lest you missed it.

The scenario begins:

"A 50-Ohm line is terminated with a load of 200+j0 ohms.
The normal attenuation of the line is 2.00 decibels.
What is the loss of the line?"

Having stated no more, the implication is that the source is matched
to the line (source Z = 50+j0 Ohms). This is a half step towards the
full blown implementation such that those who are comfortable to this
point (and is in fact common experience) will observe their answer and
this answer a

"A = 1.27 + 2.00 = 3.27dB"

"This is the dissipation or heat loss...."

we then proceed:

"...the generator impedance is 100+0j ohms, and the line is 5.35
wavelengths long."

Beware, this stumper has so challenged the elite that I have found it
dismissed through obvious embarrassment of either lacking the means to
compute it, or the ability to simply set it up and measure it. It
takes two resistors and a hank of transmission line, or what has been
described by one correspondent as:
There is no institutionalized ignorance, just a
lot of skepticism regarding the reliability of the
analysis methods and the measurement methods.
Clearly a low regard for many correspondent's abilities here, and
hardly a prejudice original to me. Imagine the incapacity of so many
to measure relative power loss - a CFA salesman's dream population.

Actually it is quite obvious several recognize that follow-through
would dismantle some cherished fantasies. Chapman clearly knocks the
underpinnings from beneath them without any further effort on my part.
But then, as you offer, they would merely dismiss it by confirming
another prejudice:
its assumed low station as a Schaum's Outline book

I would point out to all, that Chapman's material dovetails with what
would have been then current research and teachings of the National
Bureau of Standards. Prejudice has "refuted" those findings too. :-)

73's
Richard Clark, KB7QHC