Current through coils
 

On Mon, 20 Mar 2006 23:10:15 GMT, Cecil Moore
wrote:

Certainly, no repugnance or disrespect intended. Roy is presently

Couching what "appears" to be apology in a statement that projects an
answer upon Roy (and quite commonly from you, anyone) is sleazy
rhetoric.

Current through coils
 

Richard Clark wrote:
(and quite commonly from you, anyone) is sleazy
rhetoric.

No matter what I say, you consider it to be sleazy
rhetoric, Richard. It's not my problem.

I have been telling Roy this basic technical stuff
for three years or more. It's also not my problem.
--
73, Cecil http://www.qsl.net/w5dxp

Current through coils
 

Yuri Blanarovich wrote:
wrote in message
oups.com...

Yuri Blanarovich wrote:
Yea Tom, it all started with ALL coils, it is MY theory and you can ruin
MY
theory.

What is your theory Yuri?
You didn't explain it.
73 Tom


Nice twist again! (That was sarcasm and take on your comment about ALL
coils)

I didn't produce any MY theory.

OK, so you have no theory and I assume no opinion.

Good enough.

73 Tom

Current through coils
 

Cecil Moore wrote:
Certainly, no repugnance or disrespect intended. Roy is presently
in the unenviable position of agreeing with (EZNEC and me) or
disagreeing with (EZNEC and me). Hint: rhetorical questions
require no answer.
73, Cecil http://www.qsl.net/w5dxp

I'm not sure what that is all about, but Cecil....there are over 550
posts in this thing now.

Can you state in a few clearly written lines what you have learned or
concluded? If that is too involved, that's OK.

I'm just trying to understand what you point is in all of this, and
where your head is at after all the posts.

My conclusion for short mobile or fixed location loaded antennas is:

1.) If a loading coil has compact form and is terminated in a
capacitance that presents a reasonably low impedance compared to
inductor capacitance to the outside world, current taper will be
minimal. As a matter of fact, it can be immeasurable.

2.) Current taper and phase shift do not correspond to the electrical
degrees the loading coil "replaces", except as the physical size of the
loading coil might increase stray capacitance to the outside world.

3.) Phase shift of current is anything from zero to a reasonably small
number of degrees, and does not correspond to the electrical degrees
the inductor replaces.

4.) There are at least two ways to get a good answer. One is by a
circuit model with enough L and C sections, the other is with a wave
theory approximation. Both models have limits.

I think that pretty much is it. What did you conclude? Can you get it
into a few clear words?

I just want to see how far apart everyone still is.

73 Tom

Current through coils
 

wrote:
Can you state in a few clearly written lines what you have learned or
concluded?

http://www.qsl.net/w5dxp/current.htm (bottom of page)

1.) If a loading coil has compact form and is terminated in a
capacitance that presents a reasonably low impedance compared to
inductor capacitance to the outside world, current taper will be
minimal. As a matter of fact, it can be immeasurable.

Current taper depends upon where the coil is installed in the
standing wave antenna system. It can be flat, positive, or
negative. If properly placed, it can even have current flowing
into both ends of the coil at the same time, i.e. a 180 degree
phase shift in the currents at each end.

The coil distorts the current waveform away from the pure cosine
envelope presented by a 1/2 wavelength thin-wire dipole but then
so does a large diameter conductor.

2.) Current taper and phase shift do not correspond to the electrical
degrees the loading coil "replaces", except as the physical size of the
loading coil might increase stray capacitance to the outside world.

Phase shift corresponds to the delay through the coil.
It can be estimated from the self-resonant frequency
measurement where the delay is known to be 90 degrees.
This is a common method of estimating the delay (electrical
length) of a transmission line stub.

3.) Phase shift of current is anything from zero to a reasonably small
number of degrees, and does not correspond to the electrical degrees
the inductor replaces.

My 75m bugcatcher coil occupies about 60 degrees at 4 MHz,
2/3 of the electrical length of the antenna. 60 degrees doesn't
seem to meet the definition of "reasonably small". IMHO, that
would qualify as "reasonably large", i.e. more than half the
electrical length of the 75m mobile antenna.

4.) There are at least two ways to get a good answer. One is by a
circuit model with enough L and C sections, the other is with a wave
theory approximation. Both models have limits.

It is impossible to get a good answer with a model that presupposes
faster than light propagation through the coil with equal amplitudes
and phases at each end of the coil. The error is the same as assuming
such for a piece of transmission line. Dr. Corum's suggested crossover
point where the lumped-circuit model fails is 15 degrees or 0.04 of a
wavelength. Either the distributed-network model or Maxwell's equations
must be used beyond that point in order to obtain valid results.

I think that pretty much is it. What did you conclude? Can you get it
into a few clear words?

A 75m bugcatcher coil is a "slow wave structure" described by Ramo and
Whinnery, by the IEEE Dictionary, and by Dr. Corum. The velocity factor
of my 75m bugcatcher coil has been measured at ~0.017 which agrees with
the published formula.
--
73, Cecil http://www.qsl.net/w5dxp

Current through coils
 

OK, so you have no theory and I assume no opinion.
Good enough.
73 Tom


That just about summarizes you. You don't need theory, just go measure it as
I described. The theory started with Dr. Nikola Tesla and skillfully
defended by W5DXP. I don't claim to steal anybody's theory, other people
came up with explanation of the effect, I am just defending it based on
reality, burned coils and not coming up with "theory" that would back up
wrong claims.

What the hell is all the discussion about? Your misinformation on your web
site, and you can't allow to get it right, because you can't possibly be
wrong or admit to it.
Just crap, no answer to technical questions, defending your baloney. What's
your theory? RF behaves like DC in a loading coil?

ANSWER the frickin questions!!!
You can't, because you either don't get it or your ego doesn't allow you to
get it.
Pretty sad picture. I have no more to say, if you have no answers. I get
better response from a brick wall.

Just don't claim to be engineer or "JI Engineering". Engineers do not behave
like that, they have certain code of ethics and rules on usage of term
engineer and engineering. You might want to check with Georgia Engineers
association.

I am sorry about all this, but I just don't take a crap and for the umpteen
time, it just gets too much. Man who attacked misinformation on Interned on
QRZ pages is guilty of the same. K7GCO has a name for people like that:
"Technical imposters".

Sayonara!!

Yuri, K3BU

Current through coils
 

Cecil Moore wrote:
wrote:
Can you state in a few clearly written lines what you have learned or
concluded?

http://www.qsl.net/w5dxp/current.htm (bottom of page)


Thanks Cecil. I wanted to be sure where you were at now.
We still disagree about several important points.

In a few more years, there might be a resolution.

73 Tom

Current through coils
 

Grow up.

wrote in message
oups.com...

Cecil Moore wrote:
wrote:
Can you state in a few clearly written lines what you have learned or
concluded?

http://www.qsl.net/w5dxp/current.htm (bottom of page)


Thanks Cecil. I wanted to be sure where you were at now.
We still disagree about several important points.

In a few more years, there might be a resolution.

73 Tom

Current through coils
 

wrote:
Thanks Cecil. I wanted to be sure where you were at now.
We still disagree about several important points.

"The unwillingness of the "gurus" to answer specific
technical questions is pretty disappointing."
- a comment from a reader.

You said you could use the lumped-circuit model to explain
how the current at the top of the coil could be greater
than the current at the bottom of the coil as it is
at the bottom of the page at:

http://www.qsl.net/w5dxp/current.htm

If you are technically correct, why are you so technically
silent on the subject? Does the emperor have no clothes?

At least a dozen of my technical questions have gone
unanswered by being ignored. Lot's of readers have
noticed and commented in emails to me.

If you will repeat your measurements with 1/4WL added
to the top of the base-loaded mobile antenna, you will
start to understand the physics involved. The current
taper through a coil depends upon where in the standing
wave environment that the coil is installed.

The lumped-circuit analysis fails for the typical
75m amateur radio mobile antenna.
--
73, Cecil http://www.qsl.net/w5dxp

Current through coils
 

Cecil Moore wrote:

If you are technically correct, why are you so technically
silent on the subject?

I'm not silent.

I think I've done a good job of explaining things, and I've made
measurements and posted results.

At least a dozen of my technical questions have gone
unanswered by being ignored. Lot's of readers have
noticed and commented in emails to me.

So what?

1.) I told you weeks ago I'm too busy working right now to get deeply
involved in this.

2.) When measurements are made, you dismiss them as "measuring current
in a system with standing waves".

If you will repeat your measurements with 1/4WL added
to the top of the base-loaded mobile antenna, you will
start to understand the physics involved. The current
taper through a coil depends upon where in the standing
wave environment that the coil is installed.

Then why can I measure a fixed inductor location in a dfixed antenna,
and range from no taper at all in current to just under 1/3 reduction
in current? Does you standing wave model explain this very repeatable
measurement?

http://www.w8ji.com/mobile_antenna_c...ts_at_w8ji.htm

The lumped-circuit analysis fails for the typical
75m amateur radio mobile antenna.

I disagree. Unless we want to say so does the standing wave model.

The antenna can be modelled as a series of lumped inductors with
capacitance to the outside world just as well as any other method.

73 Tom