"Tarmo Tammaru" wrote in message ...

They were MIT EE professors. I think Fano has written a more recent book on
this. MIT is often considered to be the best engineering school in the US.
(Keep forgetting you live "over there")


And they never make mistakes or typos? Ok...


You are making me work my tail off trying to understand just what they did.
You have a line of impedance Zo with load Zr at point z=0. Normalize,
Zn=Zr/Zo. Since the angle of Zo is within +/- 45 degrees, the angle of Zn is
within +/-135 degrees. He draws some vectors and decides maximum gamma is
when the angle of Zn is +/-135. He solves for gamma^2, takes the square
root, and ends up with gamma =



What exactly do you mean by Zr at point z=0? i don't fully
understand the page you sent, and neither do you obviously.



1 + SQRT(2)

I couldn't massage the numbers just right, but the decimal number I got
suggest that max Gamma occurs when

Zo = k(1 - j1)
Zr = jkSQRT(2) k is the same k

He goes on to say that as you move away from z=0, the reflection coefficient
becomes smaller by e**2alpha|z|

This is probably a never ending discussion, but I wanted to point out that
these guys don't think there is anything wrong with your gamma of 1.8 ;
especially since Slick brought it up again. I do not want to retake Fields &
Waves

Tam/WB2TT


Maybe you should retake it.

If the power RC is the square of the MAGNITUDE of the voltage
RC, then a voltage RC 1 will lead to a power RC 1.

How do you get more reflected power than incident power into a
passive network, praytell??


Slick

On Thu, 28 Aug 2003 14:22:55 -0700, W5DXP
wrote:
I guess I don't understand any of the above. Coherency just means the
signals are of the identical frequency. Coherency doesn't specify phase.
The phase of a reflected wave can be anything depending on feedline
length and load.

Hi Cecil,

This shows the lack of your "optics." A laser which amplifies by
virtue of coherency, consists of a phase locked aggregation of what
would have been incoherent illuminations. It would be an LED
otherwise.

As I have said for quite a while now, it is a simple matter of
interference math. Such math shows everything of coherency or
differences. A coherent signal, is by definition of the same
frequency of another who matches that coherency.

To put it ironically, the challenge I offer is deliberately incoherent
to give that math a deliberate solution that is other than the result
of simple addition or subtraction.

73's,
Richard Clark, KB7QHC

"Dr. Slick" wrote
What about the ARRL?
================================

Dear Slick, you must be new round this neck of the
woods.

Don't you realise the ARRL bibles are written by the
same sort of people who haggle with you on this
newsgroup?

"Dr. Slick" wrote in message
om...
What exactly do you mean by Zr at point z=0? i don't fully
understand the page you sent, and neither do you obviously.


Lower case z is distance, with the load at z=0

If the power RC is the square of the MAGNITUDE of the voltage
RC, then a voltage RC 1 will lead to a power RC 1.

He squares it to get the magnitude of the vector. There is still a phase
angle

How do you get more reflected power than incident power into a
passive network, praytell??


You don't. at gamma =2.41, the phase angle is about 65 degrees, and the real
part of gamma =1.0


Now try this: using the conjugate formula, calculate gamma for the case
where the line is terminated in a short circuit, and tell us how that meets
the boundary condition.

Tam/WB2TT

Ian White, G3SEK wrote:
The reason no-one will take on your challenge is that it's an empty one:
the source impedance has no effect on the SWR, so there's nothing there
for us to prove.

I'm still trying to understand the challenge. Do you understand where
the alleged incoherence comes from?
--
73, Cecil http://www.qsl.net/w5dxp



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Yes, Richard . . .

Did you mean "Chipman" by chance?

That is the author's name . . .

--
73/72, George
Amateur Radio W5YR - the Yellow Rose of Texas
Fairview, TX 30 mi NE of Dallas in Collin county EM13QE
"In the 57th year and it just keeps getting better!"






"Richard Clark" wrote in message
...
On Thu, 28 Aug 2003 05:58:09 -0500, W5DXP
wrote:

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

What does the generator impedance have to do with line losses?

Hi Cecil,

From Chapman (you following this George?) page 28:

"It is reasonable to ask at this point how, for the circuit of
Fig. 3-1(b), page 18, on which the above analysis is based, there
can be voltage and current waves traveling in both directions on
the transmission line when there is only a single signal source.
The answer lies in the phenomenon of reflection, which is very
familiar in the case of light waves, sound waves, and water waves.
Whenever traveling waves of any of these kinds meet an obstacle,
i.e. encounter a discontinuous change from the medium in which
they have been traveling, they are partially or totally
reflected."
...
"The reflected voltage and current waves will travel back along
the line to the point z=0, and in general will be partially
re-reflected there, depending on the boundary conditions
established by the source impedance Zs. The detailed analysis of
the resulting infinite series of multiple reflections is given in
Chapter 8."

The Challenge that I have offered more than several here embody such
topics and evidence the exact relations portrayed by Chapman (and
others already cited, and more not). The Challenge, of course, dashes
many dearly held prejudices of the Transmitter "not" having a
characteristic source Z of 50 Ohms. Chapman also clearly reveals that
this characteristic Z is of importance - only to those interested in
accuracy.

Those hopes having been dashed is much evidenced by the paucity of
comment here; and displayed elsewhere where babble is most abundant in
response to lesser dialog (for the sake of enlightening lurkers no
less). Clearly those correspondents hold to the adage to choose
fights you can win. I would add so do I! The quality of battle is
measured in the stature of the corpses littering the field. :-)

So, Cecil (George, Peter, et alii), do you have an answer? Care to
take a measure at the bench? As Chapman offers, "just like optics."
Shirley a man of your erudition can cope with the physical proof of
your statements. ;-)

The only thing you and others stand to lose is not being able to
replicate decades old work. Two resistors and a hank of line is a
monumental challenge.

73's
Richard Clark, KB7QHC

On Thu, 28 Aug 2003 21:01:54 -0500, W5DXP
wrote:

Richard Clark wrote:
To put it ironically, the challenge I offer is deliberately incoherent
to give that math a deliberate solution that is other than the result
of simple addition or subtraction.

So how do you get the reflections in a single source system to be
incoherent?

Hi Cecil,

Two reflective interfaces with an aperiodic distance between.

The cable (or any transmission line) falls in between. So does most
instrumentation to measure power. All fall prey to this indeterminacy
(unless, of course, it is made determinant through the specification
of distance, which it is for the challenge). As I offered, this
challenge is not my own hodge-podge of boundary conditions, it was
literally drawn from a standard text many here have - hence the quote
marks that attend its publication by me. I am not surprised no one
has caught on, I also pointed out this discussion is covered in the
parts of Chapman that no one reads. Whatchagonnado?

The example of the challenge serves to illuminate (pun intended) the
logical shortfall of those here who insist that a Transmitter exhibits
no Z, or that it is unknowable (to them, in other words), or that it
reflects all power that returns to it (to bolster their equally absurd
notion that the Transmitter does not absorb that power). Chapman is
quite clear to this last piece of fluff science - specifically and to
the very wording. Engineers and scientists simply converse with the
tacit agreement that the source matches the line when going into the
discussion of SWR (and why Chapman plainly says this up front on the
page quoted earlier). This is so commonplace that literalists who
lack the background (and skim read) fall into a trap of asserting some
pretty absurd things. It follows that for these same literalists, any
evidence to the contrary is anathema, heresy, or insanity - people
start wanting to "help" you :-P

Ian grasped at the straw that the discussion simply peters out by the
steady state and wholly disregards the compelling evidence (and
further elaboration of Chapman to this, but he lacks another voice,
the same Chapman, to accept it) with a forced mismatch at both ends of
the line. It is impossible to accurately describe the power delivered
to the load without knowing all parameters, the most overlooked is
distances traversed by the power (total phase in the solution for
interference). I put the challenge up to illustrate where the heat
goes (the line); and it is well into the steady state, as I am sure no
one could argue, but could easily gust
"t'ain't so!"
At least I saved them from the prospect of strangling on their own
spit sputtering "shades of conjugation." [Another topic that barely
goes a sentence without being corrupted with a Z-match
characteristic.]

Using this example for the challenge forces out the canards that the
source is adjusting to the load (in fact, the challenge presents no
such change in the first place) and dB cares not a whit what power is
applied unless we have suddenly entered a non-linear physics. None
have gone that far as they have already fallen off the edge earlier.

Now, be advised that when I say "accurately" that this is of concern
only to those who care for accuracy. Between mild mismatches the
error is hardly catastrophic, and yet with the argument that the
Transmitter is wholly reflective, it becomes catastrophic. The lack
of catastrophe does not reject the math, it rejects the notion of the
Transmitter being wholly reflective. This discussion in their terms
merely drives a stake through their zombie theories.

I would add there has been another voice to hear in this matter. The
same literalist skim readers suffer the same shortfall of perception.
We both enjoy the zen-cartwheels so excellently exhibited by the drill
team of naysayers. ;-)

73's
Richard Clark, KB7QHC

On Fri, 29 Aug 2003 03:01:50 GMT, "George, W5YR"
wrote:

Yes, Richard . . .

Did you mean "Chipman" by chance?

That is the author's name . . .

Hi George,

Ha! You got me there! ;-)

And here I've been ignoring my spell checker. :-(

This will no doubt vindicate many from the minutes of drudgery of
working over a hot bench to reduce my challenge to ashes.
"The best-laid schemes o' Mice an' Men
gang aft a-gley...."

73's
Richard Clark, KB7QHC

Well, I really was hoping I'd shame someone (especially Garvin) into
_actually_ going through the math exercise. It's not all that
difficult, and as you've said before, and as I agree, they'd benefit
from actually doing it, and also from thinking about what's going on.
Some of the more subtle physics (such as phase shifts associated with
skin effect) isn't so easily accessible, but surely these things are
to those who are willing. It seems like everyone agrees fairly
readily that Zo=Vf/If=-Vr/Ir (to a good approximation, anyway), and
also to the couple other things you need to let you find Vr/Vf, but
things rather rapidly seem to fall apart along the way to Vr/Vf. I've
given up trying to understand why, Reg, so I might as well get a bit
of dry humor out of it all.

Actually, I think you _did_ state the value once or twice recently in
these annals.

Cheers,
Tom


"Reg Edwards" wrote in message ...
Tom, to save everybody a lot of trouble -

The greatest theoretical value of the magnitude of the
reflection coefficient occurs when the angle of Zo is
-45 degrees, and the terminating impedance is a pure
inductive reactance of |Zo| ohms.

Do you think I should have mentioned this when I
began this and other threads by saying a reflection
coefficient greater than unity can occur?

The riot police can now return to barracks.
----
Reg, G4FGQ.
....

(Dr. Slick) wrote in message . com...
(Tom Bruhns) wrote in message om...

Garvin, it's a book, not a paper. Your bookstore can probably help
you with it. Besser, at least, apparently came to understand the
error of his ways on this point, and Besser Associates is now
presenting the correct formula in their classes, per the email I
posted from them. I haven't checked with Pozar or Kurokawa, but
strongly suspect you are taking their works out of context and
misinterpreting them.

Cheers,
Tom


You are full of sh**. You never emailed Besser, and they are
teaching it correctly.

So why don't you email Rex Frobenius, ,
or call him at 650-949-3300, and ask him if he remembers the email he
got from me through Besser's web site last Thursday, 21 Aug.? And
while you're at it, ask him what they are _now_ teaching. By posting
stuff like the above, you're only degrading yourself. Folk here who
have known me for several years know full well that I'd check out
sources like that, and would not lie about it or fabricate a reply
such as I posted. You might consider doing yourself a favor and
growing up a bit, but in the mean time, be aware that you're providing
me with a source of humor, at your expense.

Cheers,
Tom