Roy Lewallen, W7EL wrote:
"Now explain how you`d do it with a box having only two terminals--"

I`ll give the mathematician`s answer: "It`s of no interest. It`s already
been solved." Cecil said he would put a coil in the box. I agree.
Retardation between incident and reflected waves in each direction would
in most cases cause a current difference between the two ends of the
coil. Unlike the usual transmission line, the wire is coiled to get
reactance into a small space. The effect is the same in that phase shift
is distributed along the length of the wire. There is just more of it
and and the intervals between maxima and minima are short. Impedance and
therefore voltage along the vire is a function of site along the wire.
There will be a standing wave pattern throughout the coil.

Best regards, Richard Harrison, KB5WZI

Richard,

After that response all I can say is, this newsgroup is sure good for
entertainment.

73,
Gene
W4SZ

Richard Harrison wrote:
Roy Lewallen, W7EL wrote:
"Now explain how you`d do it with a box having only two terminals--"

I`ll give the mathematician`s answer: "It`s of no interest. It`s already
been solved." Cecil said he would put a coil in the box. I agree.
Retardation between incident and reflected waves in each direction would
in most cases cause a current difference between the two ends of the
coil. Unlike the usual transmission line, the wire is coiled to get
reactance into a small space. The effect is the same in that phase shift
is distributed along the length of the wire. There is just more of it
and and the intervals between maxima and minima are short. Impedance and
therefore voltage along the vire is a function of site along the wire.
There will be a standing wave pattern throughout the coil.

Best regards, Richard Harrison, KB5WZI

Richard Harrison wrote:

Unlike the usual transmission line, the wire is coiled to get
reactance into a small space. The effect is the same in that phase shift
is distributed along the length of the wire.

W8JI measured a 60 degree phase shift through a 100uH coil
at 1 MHz. Consider that at one end of that coil the
forward and reflected currents may be:

Ifor = 0.55 amps at zero deg, Iref = 0.45 amps at zero deg.

Inet = Ifor + Iref = 1 amp at zero degrees.

At the other end of the coil, the forward and reflected
currents may be:

Ifor = 0.55 amps at +60 deg, Iref = 0.45 amps at -60 deg

Inet = Ifor*cos(60) + Iref*cos(-60)

Inet = 0.275 + 0.225 = 0.5 amps at zero deg

Some items of note:

1. The forward current magnitude is the same at both ends
2. The forward current phase is shifted by 60 degrees
3. The reflected current magnitude is the same at both ends
4. The reflected current magnitude is shifted by -60 deg
5. The forward and reflected current phasors rotate in
opposite directions
6. The net current phase is unchanged through the coil
7. The net current magnitude is changed by 100% from 0.5
amps to 1.0 amps.
--
73, Cecil http://www.qsl.net/w5dxp

Cecil Moore incorrectly posted:

W8JI measured a 60 degree phase shift through a 100uH coil
at 1 MHz. Consider that at one end of that coil the
forward and reflected currents may be:
Ifor = 0.55 amps at zero deg, Iref = 0.45 amps at zero deg.

Inet = Ifor + Iref = 1 amp at zero degrees.

At the other end of the coil, the forward and reflected
currents may be:

Ifor = 0.55 amps at +60 deg, Iref = 0.45 amps at -60 deg
Inet = Ifor*cos(60) + Iref*cos(-60)

Inet = 0.275 + 0.225 = 0.5 amps at zero deg

The above analysis clearly shows how wrong Cecil is, and how he invents
reasons to support things.

I NEVER measured a current shift of 60 degrees, and I never said I
measured a current difference of 60 degrees.

The phase shift I measured was in VOLTAGE. It simply shows the voltage
is out of step with the current. It doesn't indicate current is shifted
60 degrees between each inductor terminal at all, and I never said it
did.

The current level at each end of the inductor was, as far as I can
measure with test equipment, equal.

This is another clear case of Cecil taking things out of context and
mixing them with his idea that an inductor treats current differently,
depending on what direction it "flows" (or whatever he is claiming, I
certainly can't make sense of his arguments).

It is always better to let people directly post what they say, and not
have it run through a "Cecil Moore" filter.

73 Tom

wrote:
I NEVER measured a current shift of 60 degrees, and I never said I
measured a current difference of 60 degrees.

The phase shift I measured was in VOLTAGE. It simply shows the voltage
is out of step with the current. It doesn't indicate current is shifted
60 degrees between each inductor terminal at all, and I never said it
did.

The subject was Kraus' 180 degree current phase shifting coils. Here
are you exact words (and all of your words about that measurement)
quoted from qrz.com:

By the way, I swept S12 phase with my network analyzer on a 100uH
inductor a few hours ago while working on a phasing system. The
phase shift through that series inductor was about -60 or -70 degrees
on 1 MHz, crossing ZERO phase at self resonance (where loss became very
high) near 18 MHz, and gradually increasing leading phase above 18MHz
reaching 90 degrees and staying there well above resonance.

I apologize for missing the small detail that S12 was a voltage
measurement rather than a current measurement but I'm sure you can
see how that was an honest mistake and easy to make. You didn't
mention "voltage" at all in your posting and the context was current.
I didn't recall until your objection here today that S12 is a voltage
parameter measurement.

But that leads to a question. Why were you using voltage measurements
to try to disprove Kraus' statement about 180 degree current phase
shifting coils. Quoting from: "Antennas for All Applications", Kraus
and Marhefka, 3rd edition, page 824: "A coil (or trap) can also act
as a 180 deg (current) phase shifter as in the collinear array ...
The coil may also be thought of as a coiled-up 1/2WL element."

The current level at each end of the inductor was, as far as I can
measure with test equipment, equal.

That sure doesn't make technical sense. If there was no phase shift
in the current, then the voltage was lagging the current. But we know
the current lags the voltage through an inductor by as much as 90
degrees in the ideal case. If the voltage is delayed by 60 degrees,
then the current must necessarily be delayed by 60 degrees plus the
lag to satisfy the laws of physics. If you will run the experiment
using current probes, I assure you that the current will experience
more of a phase shift than the voltage, just as the laws of physics
predict. Which means there was more than a 60 deg current phase
shift through the coil which makes my argument even stronger.

Now, if you are talking only about the magnitude of the current then
of course, the current was equal at both ends of the coil because
reflected energy was absent for that measurement. IT IS THE PRESENCE
OF REFLECTED ENERGY THAT MAKES FALSE YOUR ASSERTION ABOUT NET CURRENT.
I think we are in perfect agreement about systems without reflections.

This is another clear case of Cecil taking things out of context ...

Not out of context, Tom. The entire quote is just above. The mistake
was an honest one and easy to make. I'm only human. :-)

and
mixing them with his idea that an inductor treats current differently,
depending on what direction it "flows" ...

Sorry, I never said that. An inductor treats forward waves and
reflected waves exactly the same according to the laws of physics.
Your statement is more akin to your idea that standing wave current
flows into the bottom of a coil and out the top. The coil treats all
traveling waves exactly according to the laws of physics and exactly
as you and I understand those laws of physics. I accept everything
you say about traveling wave current through a coil. My argument with
you is that a standing wave current is not a traveling wave current
and doesn't behave like a traveling wave current. That seems rather
obvious to me.

1. Just as you say, the forward traveling-wave current through a coil
is of constant magnitude. Here's what Walter Maxwell says: "If an
inductance is in series with a line that has no reflections, the current
will be the same at both ends of the inductor." All three of us agree on
that statment.

2. As in (1) above and just as you say, the reflected current through
a coil is of constant magnitude.

3. There is no law of physics that requires the standing wave
current to be equal at the top and bottom of a coil. In fact,
such a requirement violates those laws of physics. Here's what
Walter Maxwell says: "If an inductance is
in series with a line that has reflections, the current will NOT be
the same at both ends of the inductor. Consequently, circuit analysis
will not work when both forward and reflected currents are present
in a lumped circuit. When reflections are present, a current node
and a current loop can appear at separate points on an inductor
simultaneously." Judging from what he has posted earlier, Richard
Harrison agrees with those statements.

There's an EZNEC graphic at: http://www.qsl.net/w5dxp/qrzgif35.gif

Would you have us believe that 0.1+ amps is flowing into the bottom
of the coil and 0.7+ amps is flowing out of the top of the coil?
It is your concept that standing wave current flows that is the
problem. Please explain how a current with a zero phase angle
from tip to tip on a 1/2WL thin wire dipole can possibly flow without
a rotating phase angle.

It is always better to let people directly post what they say, and not
have it run through a "Cecil Moore" filter.

I agree, Tom, but you were not posting here so I quoted what I honestly
thought you said over on qrz.com. I quoted the same thing on qrz.com over
a number of days. You could have pointed out my mistake a lot sooner and
saved me from making it here.
--
73, Cecil http://www.qsl.net/w5dxp

Cecil Moore wrote:

[snip]


I apologize for missing the small detail that S12 was a voltage
measurement rather than a current measurement but I'm sure you can
see how that was an honest mistake and easy to make. You didn't
mention "voltage" at all in your posting and the context was current.
I didn't recall until your objection here today that S12 is a voltage
parameter measurement.

But that leads to a question. Why were you using voltage measurements
to try to disprove Kraus' statement about 180 degree current phase
shifting coils. Quoting from: "Antennas for All Applications", Kraus
and Marhefka, 3rd edition, page 824: "A coil (or trap) can also act
as a 180 deg (current) phase shifter as in the collinear array ...
The coil may also be thought of as a coiled-up 1/2WL element."

Cecil,

Interesting,

The complete quote from Kraus on page 744 in my copy of his 2nd edition is:

"A coil (or trap) can also act as a 180 degree phase shifter as in the
collinear array of 4 in-phase lambda/2 elements in Fig. 16.30b. Here the
elements present a high impedance to the coil which may be resonated
without an external capacitance due to its distributed capacitance. The
coil may also be though of as a coiled-up lambda/2 element."


* It is possible that Kraus edited the comment in the 3rd edition, but I
don't see the word "current" in this quote. It is considered good
editorial form to indicate clearly when you have altered the original
wording, unless you are trying to make a point, I suppose.

* The coil in this case is self-resonant at the frequency of use. Do you
use a self-resonant coil for your 80 meter bugcatcher? (Such a coil
might be more appropriate for a pterodactyl catcher.) In any case, this
has little to do with all of your rantings about loading coils. I
suspect even at A&M they must have mentioned something about the
characteristics of resonant circuits.

* You might have noticed the prominent role of capacitance. I believe
that was the item that spurred this thread.

73,
Gene
W4SZ

Gene Fuller wrote:
Cecil Moore wrote:
I apologize for missing the small detail that S12 was a voltage
measurement rather than a current measurement but I'm sure you can
see how that was an honest mistake and easy to make. You didn't
mention "voltage" at all in your posting and the context was current.
I didn't recall until your objection here today that S12 is a voltage
parameter measurement.

But that leads to a question. Why were you using voltage measurements
to try to disprove Kraus' statement about 180 degree current phase
shifting coils. Quoting from: "Antennas for All Applications", Kraus
and Marhefka, 3rd edition, page 824: "A coil (or trap) can also act
as a 180 deg (current) phase shifter as in the collinear array ...
The coil may also be thought of as a coiled-up 1/2WL element."

The complete quote from Kraus on page 744 in my copy of his 2nd edition is:

"A coil (or trap) can also act as a 180 degree phase shifter as in the
collinear array of 4 in-phase lambda/2 elements in Fig. 16.30b. Here the
elements present a high impedance to the coil which may be resonated
without an external capacitance due to its distributed capacitance. The
coil may also be though of as a coiled-up lambda/2 element."

* It is possible that Kraus edited the comment in the 3rd edition, but I
don't see the word "current" in this quote. It is considered good
editorial form to indicate clearly when you have altered the original
wording, unless you are trying to make a point, I suppose.

Gene, I assume you know it is common practice to insert words in
parentheses in a quotation to make the meaning clear. Such words
are understood not to be part of the quote. Since Kraus illustrated
the current, not the voltage in Figure 23-21 and earlier in figures
14-2, 14-3, and 14-4, it is rather obvious that he was talking about
a 180 degree current shift. Nowhere that I have seen does Kraus
illustrate the voltage on a standing wave antenna or talk much about
that voltage. Do you see the arrows drawn on the antenna in question?
Do you not know that an arrow drawn on a line denotes current? And
note that since all the current arrows are pointing to the right,
there is a 180 degree current phase shift in each of those phase-
shifting coils.

However, I see I should have used brackets because Kraus was already
using parentheses. I promise to do better next time.

Again, there is hardly any technical content in your reply. You have
refused to respond to the questions I listed for you in an earlier
posting. One wonders why you are avoiding the technical issues.

So I'll ask again. At http://www.qsl.net/w5dxp/qrzgif35.gif

is an EZNEC simulation. How do you explain the 0.1+ amp of current
'flowing' into the bottom of the coil and 0.7+ amp of current
'flowing' out of the top of the coil. How, exactly, is the coil
manufacturing extra current? Hint: such a thing happens all the
time in a standing wave environment because standing wave current
doesn't flow. How could it possibly flow with a constant fixed zero
degree phase angle?
--
73, Cecil http://www.qsl.net/w5dxp