Jim Kelley wrote:
Cecil Moore wrote:
Are you actually omniscient?

I know bullcrap when I see it.

So you have the omniscient gift of recognizing
bullcrap just by observing it with absolutely
no technical rebuttal and no possibility of
your being conceptually wrong? Exactly what
is it about Drs. Corum paper that you don't
understand?

Jim, if you want to retain one iota of respect,
please present a technical argument to refute
what I have asserted. Your gut feelings of
"bullcrap" are completely irrelevant. How about
your equations that prove Dr. Corums's IEEE
paper's equations are wrong?
--
73, Cecil, IEEE, OOTC, http://www.w5dxp.com

Cecil Moore wrote:
Jim, if you want to retain one iota of respect,
please present a technical argument to refute
what I have asserted.

Sorry OM, you haven't proven your argument. You've provided no
substantive data, and have shown nothing that indicates that this coil
would conduct surface waves or behave as a tightly wound slow wave
structure. It that's a Tesla coil, then so is any other coil. I'm just
stating the obvious here.

ac6xg

Jim Kelley wrote:
I'm just stating the obvious here.

One lurker stated the obvious in an email to me.
"It seems these guys will argue that black is white
if it's you that is saying white is white!"

The 75m Texas Bugcatcher loading coil satisfies the
boundary conditions given for a slow-wave structure.
What is obvious is that you and others absolutely
refuse to engage in any technical argument concerning
the subject. It is indeed obvious why you refuse to
do so.

Jim, I ask you again: How can one possibly use the
following current as reported by EZNEC to measure
the delay through a wire or through a loading coil?

EZNEC+ ver. 4.0
1/4WL vertical 5/7/2009 5:34:16 PM
--------------- CURRENT DATA ---------------
Frequency = 7.29 MHz
Wire No. 1:
Segment Conn Magnitude (A.) Phase (Deg.)
1 Ground 1 0.00
2 .97651 -0.42
3 .93005 -0.83
4 .86159 -1.19
5 .77258 -1.50
6 .66485 -1.78
7 .54059 -2.04
8 .40213 -2.28
9 .25161 -2.50
10 Open .08883 -2.71

Your silence on the subject has so far been deafening.

How do you explain Roy's (w7el) assertion at:
http://www.w8ji.com/agreeing_measurements.htm

"As described in my posting on rraa of November 11,
the inductor "replaces" about 33 electrical degrees
of the antenna."

w8ji's measurement was a 3 nS delay. If an EM wave
can travel through 33 degrees in 3 nS at 4 MHz, it
is traveling considerably faster than the speed of
light which is entirely possible with the lumped-
circuit model. How do you explain that?
--
73, Cecil, IEEE, OOTC, http://www.w5dxp.com

Cecil Moore wrote:
Jim, I ask you again: How can one possibly use the
following current as reported by EZNEC to measure
the delay through a wire or through a loading coil?

Ask as many times as you like. You're asking me explain how to use a
printout from a computer program to measure current. The question makes
no sense, Cecil. What I'd like to know is how is one supposed to
respond to such nonsense.

If what you want to know is how to measure current on a coil, I suggest
that you need to build a current probe. Ask W8JI about it. According
to your reference, the Corum paper, you would then plot current as a
function of position along the axis of the helix. From that one can
determine the axial length of the standing wave pattern - the length of
the wave, so to speak. Given the frequency and the wavelength, one can
easily arrive at the propagation velocity. If you need help with it,
good luck.

ac6xg

Jim Kelley wrote:
Ask as many times as you like. You're asking me explain how to use a
printout from a computer program to measure current. The question makes
no sense, Cecil. What I'd like to know is how is one supposed to
respond to such nonsense.

Jim, I'm sorry that you are not capable of converting
the EZNEC printout into a graph. Would you like me to
show you how to do it?

If what you want to know is how to measure current on a coil, I suggest
that you need to build a current probe. Ask W8JI about it. According
to your reference, the Corum paper, you would then plot current as a
function of position along the axis of the helix. From that one can
determine the axial length of the standing wave pattern - the length of
the wave, so to speak. Given the frequency and the wavelength, one can
easily arrive at the propagation velocity. If you need help with it,
good luck.

You're preaching to the choir, Jim. You and I know that
the phase information for a standing wave is contained
in the amplitude and the phase relative to time is constant
at all points on the antenna for any particular time.

What you should be doing is explaining that to w7el and
w8ji because they don't seem to understand that the
current phase in standing wave antennas does NOT change
with distance. Here's an earlier question that you guys
ignored. Given a 1/2WL dipole with current probes at x and y:

---------------------------fp--------x--------y---------

points x and y are 30 degrees apart. What will be the
difference between the phase of the current at x and
the phase of the current at y? EZNEC says ~1 degree.
How can current phase change by one degree in 30
degrees of wire?
--
73, Cecil, IEEE, OOTC, http://www.w5dxp.com

Jim Kelley wrote:
Cecil Moore wrote:
Jim, if you want to retain one iota of respect,
please present a technical argument to refute
what I have asserted.

Sorry OM, you haven't proven your argument. You've provided no
substantive data, and have shown nothing that indicates that this coil
would conduct surface waves or behave as a tightly wound slow wave
structure. It that's a Tesla coil, then so is any other coil. I'm just
stating the obvious here.

ac6xg


Cecil's using the old "You cain't prove it ain't" argument. Where has
that come up before?
73,
Tom Donaly, KA6RUH

Tom Donaly wrote:
Cecil's using the old "You cain't prove it ain't" argument.

I have presented my arguments. Nobody has refuted
them technically. All the objections have been ad
hominem or based on false premises.

A 75m Texas Bugcatcher coil meets the Corum test
for a helical sheath. That test is on page 4 of:

http://www.ttr.com/TELSIKS2001-MASTER-1.pdf

"... is valid for helices with 5ND^2/WLo 1
where N is the TPI and D is the diameter."

That figure is 0.244 1 for the 75m Texas Bug
Catcher used on 4 MHz.

5*4*6^2/2952 = 0.244

So all you guys have to do to shoot down my analysis
is to prove that 0.244 is not less than one.
--
73, Cecil, IEEE, OOTC, http://www.w5dxp.com

Still here, and still trying to strip away the personal attacks to try
to understand the various underlying technical opinions!

When I model a "bugcatcher" plus stinger using EZNEC, I see
significantly less current at the top of the coil compared with the
bottom of the coil. I also see a slight increase in current part way
up the coil before it then decreases towards the top.

In reply to an earlier question of mine, Roy assured me that this
current distribution was "real" and not some problem that EZNEC has
modelling this arrangement.

I have two questions if I may:

1) Cecil: I believe I understand how the Corum transmission line model
accounts nicely for the reduced current at the top of the coil. Does
it also account for the slight increase in current a short way from
the bottom?

2) Jim, Tom, Roy (and any others): It appears you think the Corum
model is flawed, or not appropriate to the "bugcatcher". What I've not
yet understood is what alternative model you are advocating which
would match the EZNEC results more closely than the Corum model. I've
heard at least Roy say that a lumped-inductor model is inappropriate,
but I don't think I've yet heard any other model proposed. Perhaps I
missed it?

Regards,
Steve G3TXQ

wrote:
Still here, and still trying to strip away the personal attacks to try
to understand the various underlying technical opinions!

When I model a "bugcatcher" plus stinger using EZNEC, I see
significantly less current at the top of the coil compared with the
bottom of the coil. I also see a slight increase in current part way
up the coil before it then decreases towards the top.

In reply to an earlier question of mine, Roy assured me that this
current distribution was "real" and not some problem that EZNEC has
modelling this arrangement.

I have two questions if I may:

1) Cecil: I believe I understand how the Corum transmission line model
accounts nicely for the reduced current at the top of the coil. Does
it also account for the slight increase in current a short way from
the bottom?

2) Jim, Tom, Roy (and any others): It appears you think the Corum
model is flawed, or not appropriate to the "bugcatcher". What I've not
yet understood is what alternative model you are advocating which
would match the EZNEC results more closely than the Corum model. I've
heard at least Roy say that a lumped-inductor model is inappropriate,
but I don't think I've yet heard any other model proposed. Perhaps I
missed it?

Regards,
Steve G3TXQ

EZNEC _is_ a model. If you can accept that, then you've got your model.
If you want to know why current is less at one end of the bugcatcher
coil than at the other, you'll have to study electromagnetic theory.
(Try adding a large top hat to the bug catcher and see what that does
to the current in the coil.) If you're satisfied with Cecil's work,
fine. Whatever works for you. Rules of thumb and such sometimes work
pretty well. The late Reg Edwards knew that and worked out some programs
that relied on such. You might want to see if you can find some of his
work on the web.
73,
Tom Donaly, KA6RUH

wrote:
1) Cecil: I believe I understand how the Corum transmission line model
accounts nicely for the reduced current at the top of the coil. Does
it also account for the slight increase in current a short way from
the bottom?

I will say, apparently not. The Corum equations are stated
to be plus or minus 10 percent. The current increase in the
coil appears to be about 10%.

Typically, the current increases from a normalized 1.0 at
the bottom of the coil to about 1.1 close to the middle
and then falls off from there to 0.8 or so. Empirically,
it seems that one can take the rise in current, i.e. 0.1,
from the bottom of the coil to the middle of the coil and
subtract that value from the current at the top of the
coil to compensate mathematically for the curve not being
a pure cosine curve because of end-effects of the coil.

Example: Given a coil with a current of 1.0 at the bottom,
1.1 at the midpoint, and 0.8 at the top. It appears that
the ARCCOS(0.8-0.1) = ARCCOS(0.7) may yield an approximation
for the delay in degrees through the coil, i.e. ARCCOS(0.7)
equals ~45 degrees.

This makes sense to me since the current profile through
the coil is obviously not a pure cosine wave. It is obviously
distorted by the turn-to-turn coupling of the fields. But
just as obviously, this is an empirical curve-fitting technique
as used by Drs. Corum.
--
73, Cecil, IEEE, OOTC, http://www.w5dxp.com