Current across the antenna loading coil - from scratch
 

On Wed, 12 Apr 2006 19:04:18 GMT, Cecil Moore
wrote:

Richard Clark wrote:

Cecil Moore wrote:
When trimming one line attributes the posting to a completely
different person, that is a clear violation.

Is that an RMS Net violation of the superposition of all violations
considererd?

Tsk, tsk, Richard, are you defending false attributions?

Tsk Tsk? to what accuracy ±59%?

Current across the antenna loading coil - from scratch
 

On Wed, 12 Apr 2006 19:02:56 GMT, Cecil Moore
wrote:

Richard Clark wrote:

Cecil Moore wrote:
That's a legal term under Texas law.

Oh, must be Phil then, Herr Doktor never explains anything.

I thought the explanation was obvious. If I am going to
get sued because of false attributions, I need a paper
trail and proof that I objected to those false attributions.

Paper trail? Phil, push over those stacks of "research" and fire up
the Xerox!

Current across the antenna loading coil - from scratch
 

Roy Lewallen wrote:
Agreed, it's not quite stated as such. Here are some statements which
were made:

From your web page http://www.k3bu.us/loadingcoils.htm, in bold type:

"In summary:
The current in a typical loading coil in the shortened antennas drops
across the coil roughly corresponding to the segment of the radiator it
replaces."

By Cecil, on March 5, on this newsgroup:
The coil occupies roughly the same number
of degrees of the antenna as the wire it replaces.

Roy, maybe you need to learn the definition of "roughly".
It is certainly not "exactly" as you are clutching at straws
to imply. Why you need to change the definitions of words
is obvious from your flawed arguments. Exactly what is
it about "roughly" that you don't understand?

It's getting muddier and muddier just what you mean by "replace".

That meaning has never been in doubt. "Replace" has always
meant bringing the necessary signals back into phase so the
feedpoint impedance is purely resistive. You know perfectly
well that it has never been about physical length or radiation.
Those are just another two of your straw men. Your attempt
to muddy those waters has been going on for years including
your attempt to discredit the distributed network model in
favor of the lumped circuit model. Hint: The distributed
network model is a superset of the lumped circuit model.
If you succeed in discrediting the distributed network
model, you have automatically succeeded in discrediting
the lumped circuit model. It's a lose-lose proposition
for you.
--
73, Cecil http://www.qsl.net/w5dxp

Current across the antenna loading coil - from scratch
 

Richard Clark wrote:
Paper trail? Phil, push over those stacks of "research" and fire up
the Xerox!

I am indeed printing out the postings just in case the false
attributions result in a lawsuit against me. I can't afford
not to be careful.
--
73, Cecil http://www.qsl.net/w5dxp

Current across the antenna loading coil - from scratch
 

On Wed, 12 Apr 2006 19:24:27 GMT, Cecil Moore
wrote:

Richard Clark wrote:
Paper trail? Phil, push over those stacks of "research" and fire up
the Xerox!

I am indeed printing out the postings just in case the false
attributions result in a lawsuit against me. I can't afford
not to be careful.

But you CAN afford to be paranoid? What a WUSS!

Current across the antenna loading coil - from scratch
 

Richard Clark wrote:
But you CAN afford to be paranoid? What a WUSS!

It doesn't cost anything to be paranoid. :-)
--
73, Cecil http://www.qsl.net/w5dxp

Current across the antenna loading coil - from scratch
 

Cecil Moore wrote:


Roy, maybe you need to learn the definition of "roughly".
It is certainly not "exactly" as you are clutching at straws
to imply. Why you need to change the definitions of words
is obvious from your flawed arguments. Exactly what is
it about "roughly" that you don't understand?

Cecil,

Is 10 degrees of phase shift "roughly" equal to 75 degrees of phase
shift? I don't think anyone is trying to nit-pick the numbers to a
precision of several significant figures. A multiple of greater than 7
would seem to be just a bit outside the scope of "roughly".

73,
Gene
W4SZ

Current across the antenna loading coil - from scratch
 

Ian White GM3SEK wrote:

Ian, I am leaving on a 6 state motorcycle trip and won't be
back until Monday. I would like for you to answer this
question while I am gone.

I've heard that, while operating portable, if I attach
a wire to my 75m mobile whip and run it up a tree, I
will be able to make more contacts. So I attach a 1/4WL
wire to the whip of my 75m mobile bugcatcher system.

I decide to measure the current "into" the bottom of the
coil and "out" of the top of the coil. To my utter amazement
I measure 1.3 amps flowing "into" the bottom of the coil and
2.1 amps flowing "out" of the top of the coil.

How does your lumped circuit theory explain that? Where is
that extra 0.8 amps of current coming from?

Please don't insult our intelligence by saying it cannot
happen. It does happen. I suspect you are at a loss to
explain it.
--
73, Cecil http://www.qsl.net/w5dxp

Current across the antenna loading coil - from scratch
 

Gene Fuller wrote:
Is 10 degrees of phase shift "roughly" equal to 75 degrees of phase
shift?

Of course not. The 10 degrees of phase shift has already been
proven to be wrong because of reflections within the coil.
Why do you insist on bringing up old invalid data?

Please note that *nobody* is alleging that the phase shift
through a 75m bugcatcher coil is 75 degrees. That is just
another one of your straw men.

Now why don't you become a rational, ethical person and
suggest a valid way of measuring the phase shift through
a coil? Can you improve on my suggestion of yesterday?
--
73, Cecil http://www.qsl.net/w5dxp

Current across the antenna loading coil - from scratch
 

Cecil Moore wrote:
Ian White GM3SEK wrote:
Now what happens if the load is not exactly 50 ohms?

If the feedline is 50 ohms, what happens is reflected
energy that is easily visible using a TDR, time domain
reflectometer.

One is that if the meter scale says "power", then there genuinely
are forward and reflected traveling waves of power on the line. In the
"93 - 23 = 70W" example, the belief is that there genuinely is a
power flow of 93W towards the load, only 70W of which is accepted and
23W is returned.

One correction. The Bird wattmeter is installed at a point
on the transmission line and it measures the power at that
point. What is traveling is the energy. Power is the number
of joules per second passing a fixed point. "Power flow" is
somewhat of a misnomer.

Sorry, you're right about "power flow". What I meant was a forward
travelling wave carrying 93W towards the load.


The other school of thought is that that's not true. The meter may
*read* more "forward power" than is actually being delivered to the
load, but that is a false indication because the instrument is not
being used in the situation for which the power scale was calibrated.

It certainly is being used in the situation for which it was
calibrated if the Z0 of the transmission line is 50 ohms.

I'm not sure which "transmission line" you meant here, but I don't think
it matters anyway.

The inserts are individually calibrated with a 50 ohm load impedance
connected to the "Antenna" socket. The internal pot is adjusted to give
the correct power reading (at one point on a meter scale that is
pre-printed), and then the insert is reversed and a tab is bent to
adjust the capacitive coupling to give the lowest possible reading.
There may be some interaction requiring the two adjustments to be
repeated, I don't know.

If you meant the transmission line outside of the instrument, the
calibration load may or may not include a length of matched 50 ohm
transmission line - it doesn't matter. Inside the instrument, the
characteristic impedance of the internal line is 50 ohms in order to
avoid introducing an impedance bump into a system that is already
matched, but even with say a 57 ohm internal line, the Bird insert could
be set up to indicate power correctly into a 50 ohm load. The only
difference is that the performance would become frequency-sensitive.


On the other hand, we have yet to see an explanation in equivalent
physical detail that is based entirely and exclusively on the
viewpoint of travelling waves of power ...

Please give up on your misconception. Those are traveling waves
of *ENERGY*. Power is what is measured when traveling energy passes
a fixed point. Perhaps that is your whole point of confusion.

You're right, they would indeed be travelling waves of energy rather
than power. But otherwise the same challenge is still out the if
forward and reflected travelling waves of energy exist, we would expect
to see a detailed explanation of how the Bird or any similar instrument
interacts with such waves as distinct from the explanations that we
already have for travelling waves of voltage and current.


--
73 from Ian GM3SEK 'In Practice' columnist for RadCom (RSGB)
http://www.ifwtech.co.uk/g3sek