On Mon, 10 Nov 2003 00:50:55 -0800, Roy Lewallen
wrote:

Ok. So far, we have your calculation that the output current should be
5% smaller, and 18 degrees shifted in phase (lagging, I presume) from
the input; and Cecil's, that the output current should equal the
current, both in phase and magnitude. I don't know if Richard is going
to do the calculation or not, so I'll wait a little longer. Anyone else
like to hazard a prediction?

Roy Lewallen, W7EL

(1) Input current = output current
(2) No phase shift.

If you model the circuit using the lumped values for the antenna R and
jX components it's easy to see this.

Anyone not believing this can try modeling the base inductor as:
O----[0.3 ohms R']--[+j192 ohms]---[0.3 ohms R'']----0
Put current through it using your favorite SPICE simulator and compare
the current through the R' and the R''. The two plots coincide.





Jack K8ZOA

Roy, W7EL wrote:
"---feedpoint impedance of 35-j370 at 3.8 MHz. Choose an inductor value
and let me know what the output : input current ratio would be for that
inductor at the base of the antenna. Assume that the inductor is
physically small."

I`ll assume the inductor has no resistance, loss or radiation.

No loss or radiation means the inductance only delays current in the
antenna circuit by the phase angle impedance makes with resistance in
the circuit.

We need 370 ohms of inductive reactance to counteract the capacitive
reactance of the too short antenna. That calculates to 10.926
microhenry.

The current into the resonant antenna circuit is E/R = E/35

The current into the too short antenna alone is E/Z = E/ 371.65

The output : input ratio of the inductor is very nearly one because the
coil is lossless and its size is insignificant in terms of wavelength.

Best regards, Richard Harrison, KB5WZI

Jack Smith wrote:
(1) Input current = output current
(2) No phase shift.

If you model the circuit using the lumped values for the antenna R and
jX components it's easy to see this.

Anyone not believing this can try modeling the base inductor as:
O----[0.3 ohms R']--[+j192 ohms]---[0.3 ohms R'']----0
Put current through it using your favorite SPICE simulator and compare
the current through the R' and the R''. The two plots coincide.

We know what the model says. The original argument was over whether a
75m bugcatcher coil, containing distributed resistance, inductance, and
capacitance, actually possesses those same characteristics in reality.
A statement by a ham over on eham.net triggered the argument:

"If you look at HOW an inductor works, the current flowing in one terminal
ALWAYS equals the current flowing out the other terminal. "

That is how a lumped inductor works in a model. That is not how a distributed
inductor works in reality.
--
73, Cecil http://www.qsl.net/w5dxp



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Roy Lewallen wrote:
And, Art, I'm surprised at your objecting to my bringing up the dreaded
complexity of -- gasp -- phase.

Here's a bench experiment that could be done concerning phase.
Create artificial standing waves with two signal generators equipped
with circulator loads (SGCL).

I1 I2
SGCL1----coil----SGCL2

Vary the phase of one of the signal generators while monitoring the
total current at each end of the coil. The equation for the total
current will be similar to the equation for total current in a
standing wave antenna, i.e. the phasor difference of I1 - I2. The
delay through the coil takes the two currents in opposite phase
directions.
--
73, Cecil http://www.qsl.net/w5dxp



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"Roy Lewallen" wrote in message
...
Jim, it sounds like you're firmly in the camp that believes that a phase
and/or magnitude shift will occur from one terminal to the other of a
physically very small inductor.

Physically very small.........what is that? Is it an inductor that behaves
as if it has no physical dimensions? Does it comprise a coil of wire that
has zero length?

Perhaps you can also propose an inductor I can put at
the base of a short antenna that would guarantee a large phase shift
which would be large and easily seen in a measurement.

How about if I just refer you to one of the many manufacturers of such
things?

73, Jim AC6XG


Roy Lewallen, W7EL

Jim Kelley wrote:
"Roy Lewallen" wrote in message
...

I did read what you said. You said that it wouldn't exhibit a phase
shift if placed at a current maximum. The current at the base of a short
vertical antenna is at its maximum there. So now if you're saying that
it *won't* exhibit a phase shift if placed at the base of a short
antenna, let's try this.


Naturally, the inductance of the coil and the resistance of the circuit
determine how much of a phase shift there will be. But the amount of
resulting change in current magnitude will depend on where on the cosine
curve this shift occurs. A 10 degree phase shift from 40 to 50 degrees
generates almost an order of magnitude greater change in current that it
does shifting from 0 to 10 degrees. Obviously, the closer the center
of
the coil is to zero (or 180) degrees, the smaller the resulting
differential
in current across the coil.

73, Jim AC6XG

On Tue, 11 Nov 2003 10:31:35 -0600, Cecil Moore
wrote:

Jack Smith wrote:
(1) Input current = output current
(2) No phase shift.

If you model the circuit using the lumped values for the antenna R and
jX components it's easy to see this.

Anyone not believing this can try modeling the base inductor as:
O----[0.3 ohms R']--[+j192 ohms]---[0.3 ohms R'']----0
Put current through it using your favorite SPICE simulator and compare
the current through the R' and the R''. The two plots coincide.

We know what the model says. The original argument was over whether a
75m bugcatcher coil, containing distributed resistance, inductance, and
capacitance, actually possesses those same characteristics in reality.
A statement by a ham over on eham.net triggered the argument:

"If you look at HOW an inductor works, the current flowing in one terminal
ALWAYS equals the current flowing out the other terminal. "

That is how a lumped inductor works in a model. That is not how a distributed
inductor works in reality.


My understanding of the particular question being debated is that the
loading coil is physically small and at the frequency in question may
be safely treated as a lumped element, and that some have said that
current-in current-out.

The fact that the small coil is connected to an antenna which is not
physically small is immaterial.

I apologize if I've misunderstood where this topic is at; it's been
very difficult to follow as it drifts back and forth.


Jack

Jim Kelley wrote:
"Roy Lewallen" wrote in message
...

Jim, it sounds like you're firmly in the camp that believes that a phase
and/or magnitude shift will occur from one terminal to the other of a
physically very small inductor.


Physically very small.........what is that? Is it an inductor that behaves
as if it has no physical dimensions? Does it comprise a coil of wire that
has zero length?


Perhaps you can also propose an inductor I can put at
the base of a short antenna that would guarantee a large phase shift
which would be large and easily seen in a measurement.


How about if I just refer you to one of the many manufacturers of such
things?

73, Jim AC6XG

I was looking for a value, not a part number.

You've said that because the inductor I chose is something like 4%
larger than necessary to resonate the antenna, the magnitude and phase
shift from input to output would be very nearly zero (although the
reasoning is contrary to conventional electrical circuit theory, and I
don't follow it at all). So what I'm asking for is an inductor value
which would exhibit a large enough phase and/or magnitude shift that
would be easily seen in a measurement. I'll be constructing a more ideal
33 foot vertical in the near future, and making similar measurements at
3.8 MHz. So if its feedpoint impedance is, let's say, 35 - j370, what
would be the input to output current ratio (magnitude and phase) for a
physically very small base inductor of, say, +j300 ohms? If it's very
small, then pick an inductor value which would exhibit a substantial
input:output current ratio.

Roy Lewallen, W7EL

Hm. Let's suppose the inductor had a loss resistance of, say, 35 ohms
(equal to the resistive part of the antenna input Z). What would the
ratio be then? This is assuming the loss is dissipative and not "loss"
due to radiation.

Roy Lewallen, W7EL

Richard Harrison wrote:
. . .
The output : input ratio of the inductor is very nearly one because the
coil is lossless and its size is insignificant in terms of wavelength.

Anyone who understands basic circuit theory knows this. But that doesn't
include a number of the participants of this newsgroup. Otherwise, the
thread would have been about two postings long.

Roy Lewallen, W7EL

Jack Smith wrote:
On Mon, 10 Nov 2003 00:50:55 -0800, Roy Lewallen
wrote:


Ok. So far, we have your calculation that the output current should be
5% smaller, and 18 degrees shifted in phase (lagging, I presume) from
the input; and Cecil's, that the output current should equal the
current, both in phase and magnitude. I don't know if Richard is going
to do the calculation or not, so I'll wait a little longer. Anyone else
like to hazard a prediction?

Roy Lewallen, W7EL


(1) Input current = output current
(2) No phase shift.

If you model the circuit using the lumped values for the antenna R and
jX components it's easy to see this.

Anyone not believing this can try modeling the base inductor as:
O----[0.3 ohms R']--[+j192 ohms]---[0.3 ohms R'']----0
Put current through it using your favorite SPICE simulator and compare
the current through the R' and the R''. The two plots coincide.





Jack K8ZOA

Jack Smith wrote in message . ..
On Mon, 10 Nov 2003 00:50:55 -0800, Roy Lewallen
wrote:

Ok. So far, we have your calculation that the output current should be
5% smaller, and 18 degrees shifted in phase (lagging, I presume) from
the input; and Cecil's, that the output current should equal the
current, both in phase and magnitude. I don't know if Richard is going
to do the calculation or not, so I'll wait a little longer. Anyone else
like to hazard a prediction?

Roy Lewallen, W7EL

(1) Input current = output current
(2) No phase shift.

If you model the circuit using the lumped values for the antenna R and
jX components it's easy to see this.

Anyone not believing this can try modeling the base inductor as:
O----[0.3 ohms R']--[+j192 ohms]---[0.3 ohms R'']----0
Put current through it using your favorite SPICE simulator and compare
the current through the R' and the R''. The two plots coincide.


Very good Jack,
Now use your skills on a inductance that is NOT
a lumped load, and don't forget its orientation so that any
coupling to ground shows up since the subject of discussion
is a loaded whip antenna.
Ofcourse if you have a pure lumped load
kindly take it to the lab for measurement purposes.
Not sure if it will be too heavy now that you have removed
the resistance , capacitance and non current carrying parts
so keep a wheel barrow at hand. grin
Art




Jack K8ZOA

"Roy Lewallen" wrote in message
...
You've said that because the inductor I chose is something like 4%
larger than necessary to resonate the antenna, the magnitude and phase
shift from input to output would be very nearly zero (although the
reasoning is contrary to conventional electrical circuit theory, and I
don't follow it at all).

Don't know. Didn't say it. Can't help.

So what I'm asking for is an inductor value
which would exhibit a large enough phase and/or magnitude shift that
would be easily seen in a measurement.

Do we agree that the amount of differential will depend on the number of
'degrees missing' from the length of the antenna?

Do we agree that the position of the loading coil plays a significant.
role in determining how much of a current differential will appear across
it?

I'll be constructing a more ideal
33 foot vertical in the near future, and making similar measurements at
3.8 MHz. So if its feedpoint impedance is, let's say, 35 - j370, what
would be the input to output current ratio (magnitude and phase) for a
physically very small base inductor of, say, +j300 ohms? If it's very
small, then pick an inductor value which would exhibit a substantial
input:output current ratio.

Are you going to insist that it be one of these ferrite core jobs, or is it
more like ones on a HF6V?

73, Jim AC6XG

It sounds like the predictions are in. Among the several people who
believe that the current out of a small inductor doesn't equal the
current in, only Yuri was able to calculate a predicted value for the
test, of 2.5 - 5% reduction in current at the output compared to the
input, with a phase shift of about 18 degrees.

What I measured was a 3.1% reduction in magnitude from input to output,
with no discernible phase shift. The 3.1% is an average of two readings,
with the input and output probes exchanged. The output was smaller than
the input in both measurements, about 2% and 4%. So I believe there's a
real difference between output and input current, although with the
accuracy of my measurements, I only have reasonable confidence it's
somewhere between 1 and 5%. I can resolve about 2-3 degrees of phase
shift, though, and I couldn't discern any at all. (Yes, the scope
trigger was from one channel, not alternating.) So I have very high
confidence that Yuri's prediction of 18 degrees is incorrect.

I don't subscribe to the notion that the current out of a very small
inductor should be different than the current in due to some magical
property it acquires when connected to an antenna. My working hypothesis
is that the currrent difference I did see was due to stray capacitance,
either from the probes or simply to the Earth and other objects. It
would take an equivalent of 6.8 pF at the output of the coil (that is,
between the coil output and the current probe) to get 3% reduction, and
only about 1/3 that amount to see the minimum value of reduction of 1% I
estimate was actually present.

I repeated the test on the bench, with a 36 ohm resistor in series with
a 220 pF capacitor substituting for the antenna. The result was a 2.3%
output:input reduction, again with no discernible phase shift. This is
within the measurement error of being the same result. This is what
should be expected -- except for unintentional coupling to the antenna's
field, the inductor's environment is the same on the bench as at the
antenna base, in these single frequency, steady state tests. (That also
contradicts what some newsgroup participants have been claiming.)

So, although the small output:input current reduction was within Yuri's
prediction, the phase shift certainly wasn't. If time permits, I'll make
a more idealized antenna and repeat the measurements with a larger
inductor at the base of a more reactive antenna. I'll predict in advance
that if I double the amount of loading L, I'll approximately double the
amount of current magnitude attenuation -- that is, to somewhere around
6%. That's what should be expected if the cause of the attenuation is
stray C or a similar phenomenon.

I've added a picture to the
http://eznec.com/rraa/Inductor_Current_Measurement.html page, showing
the overall setup including the scope. It gives a little better
perspective on the relative sizes of various objects.

Roy Lewallen, W7EL

On Tue, 11 Nov 2003 13:14:56 -0500, Jack Smith
wrote:

On Tue, 11 Nov 2003 10:31:35 -0600, Cecil Moore
wrote:

The original argument was over whether a
75m bugcatcher coil, containing distributed resistance, inductance, and
capacitance, actually possesses those same characteristics in reality.

I apologize if I've misunderstood where this topic is at; it's been
very difficult to follow as it drifts back and forth.

Hi Jack,

No apology is required from you. This thread has a very specific
question from a single correspondent (Roy). The substituted topic
that you find confusion with is a common form of (Cecil's) not being
responsive to the topic by deflection to other issues. The comedy
consists of the "gentlemen's agreement" to not cut this short when
this occurs.

But such is the gamesmanship that is being conducted, from the start.
The withholding of data to embarrass correspondents is not uncommon.
Lord knows how many I've embarrassed with simpler topics (the current
crew being only a subset). However, I generally restrain my
participation such that those threads are smaller. Otherwise the
posting of:
On Tue, 11 Nov 2003 10:26:32 -0800, Roy Lewallen wrote:

Otherwise, the
thread would have been about two postings long.
which totals 75 (soon to be 76 with this), and for which Roy has
contributed very little new details, nor any data across the majority
of 27 of his own (appealing for inductor values to force the issue
would have made the thread three postings long, c'mon now) obviously
reveals that entertainment is being served. OK, OK, for the sake of
the mythical lurker, we can all give a wink and a nod that it is
"edutainment."

I hope none expect an Emmy for these sweeps. [I would like to thank
all my books and their authors; and especially the large supporting
cast, all the little people, for making this possible.]

73's
Richard Clark, KB7QHC

Jack Smith wrote:
My understanding of the particular question being debated is that the
loading coil is physically small and at the frequency in question may
be safely treated as a lumped element, and that some have said that
current-in current-out.

A 200 cubic inch 75m bugcatcher coil is NOT physically small and should
NOT be treated as a lumped element if one desires real-world results.
--
73, Cecil http://www.qsl.net/w5dxp



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Roy Lewallen wrote:
So what I'm asking for is an inductor value
which would exhibit a large enough phase and/or magnitude shift that
would be easily seen in a measurement.

How about a coil with 180 degree phase shift as described by Kraus?

"A coil can also act as a 180 degree phase shifter as in the collinear
array of 4 in-phase 1/2WL elements in Fig. 23-21b. 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 thought of as a coiled-up 1/2WL element."

Here's the diagram in 23-21b

--------------coil-------------FP---------------coil----------------
1/2WL 1/2WL 1/2WL 1/2WL

The coils are designated as "Phase-reversing". Each coil occupies 1/2WL
electrically.

Have you never encountered phased arrays like the above or understood
that the coils are causing a 180 degree phase shift? That's the way
my Diamond 440 MHz mobile antenna works.
--
73, Cecil http://www.qsl.net/w5dxp



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Roy Lewallen wrote:
Anyone who understands basic circuit theory knows this. But that doesn't
include a number of the participants of this newsgroup. Otherwise, the
thread would have been about two postings long.

Too bad lumped inductors bear absolutely no resemblance in reality to
75m bugcatcher coils. Don't you believe Kraus when he says 180 degrees
of current phase shift can be accomplished by a single coil in a wire
antenna?

I once had an engineer like you working for me. He took four man-months
to engineer and breadboard a design that was over budget and out of spec.
I, a VP, turned out another design (from scratch) in one long weekend that
was under budget and exceeded the specs.
--
73, Cecil http://www.qsl.net/w5dxp



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Richard Clark wrote:
This thread has a very specific
question from a single correspondent (Roy).

Huh? This thread is a direct result of W8JI's alleged assertion that
the current into a coil and out of a coil is always the same or else
Kirchhoff's law is violated. Here is the quote, allegedly from W8JI,
that started this whole discussion.

"If you look at HOW an inductor works, the current flowing in one terminal
ALWAYS equals the current flowing out the other terminal."

Have you been on vacation or what?
--
73, Cecil http://www.qsl.net/w5dxp



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Cecil, W5DXP wrote:
"Here is the diagram in 23-21b."

Thanks, Cecil. My copy of Kraus is new and I`d not yet read page 824.
Kraus says:

"The coil may also be thought of as a coiled-up halfwave element."

I like his preceding sentence:

"Here the elements present a high impedance to the coil which may be
resonated without external capacitance due to its distributed
capacitance."

A "phase reversing coil" does present a 180-degree phase shift between
its ends.

Best regards, Richard Harrison, KB5WZI

I, a VP, turned out another design (from scratch) in one long weekend that
was under budget and exceeded the specs.
--
73, Cecil http://www.qsl.net/w5dxp

====================================

A design which 'exceeds' specified performance is as poor as one which
'under exceeds'.

Significant deviations in either direction are sure indications of poor
engineering education and incompetence.

Both deviations are equally expensive and wasteful in terms of time,
materials and labour.

Even kids living with rats in the sewers of Rio de Janerio know this.

Rats themselves are highly intelligent, abundent, successful animals.

Should our campuses be transferred? ;o)
---
Reg.

Now, that's quite an insult, based on a total lack of information about
my career and what I've accomplished.

I'm going to do my best to ignore Cecil's postings from here on. They're
abusive and insulting. And any time he's asked for a number,
calculation, or equation to back his point of view, he dodges, ducks,
and diverts -- and insults.

Some of the readers are undoubtedly impressed by this. That's fine --
those readers won't benefit from my postings anyway.

Roy Lewallen, W7EL

Cecil Moore wrote:
Roy Lewallen wrote:

Anyone who understands basic circuit theory knows this. But that
doesn't include a number of the participants of this newsgroup.
Otherwise, the thread would have been about two postings long.


Too bad lumped inductors bear absolutely no resemblance in reality to
75m bugcatcher coils. Don't you believe Kraus when he says 180 degrees
of current phase shift can be accomplished by a single coil in a wire
antenna?

I once had an engineer like you working for me. He took four man-months
to engineer and breadboard a design that was over budget and out of spec.
I, a VP, turned out another design (from scratch) in one long weekend that
was under budget and exceeded the specs.

Can we make a physically small "phase reversing coil" that has 180
degree phase shift between its ends? If so, how?

Roy Lewallen, W7EL

Richard Harrison wrote:
Cecil, W5DXP wrote:
"Here is the diagram in 23-21b."

Thanks, Cecil. My copy of Kraus is new and I`d not yet read page 824.
Kraus says:

"The coil may also be thought of as a coiled-up halfwave element."

I like his preceding sentence:

"Here the elements present a high impedance to the coil which may be
resonated without external capacitance due to its distributed
capacitance."

A "phase reversing coil" does present a 180-degree phase shift between
its ends.

Best regards, Richard Harrison, KB5WZI

Jim Kelley wrote:
"Roy Lewallen" wrote in message
...

You've said that because the inductor I chose is something like 4%
larger than necessary to resonate the antenna, the magnitude and phase
shift from input to output would be very nearly zero (although the
reasoning is contrary to conventional electrical circuit theory, and I
don't follow it at all).


Don't know. Didn't say it. Can't help.

I apologize. I looked back at what I thought you had said, and I was
mistaken.


So what I'm asking for is an inductor value
which would exhibit a large enough phase and/or magnitude shift that
would be easily seen in a measurement.


Do we agree that the amount of differential will depend on the number of
'degrees missing' from the length of the antenna?

No. In a few minutes, I'll post a description of a more recent
measurement I made that refutes this. Of course, elementary circuit
theory refutes it also, which is the basis for my disagreement.

Do we agree that the position of the loading coil plays a significant.
role in determining how much of a current differential will appear across
it?

If you're talking about a physically long coil, yes. If you're talking
about a physically small coil, no.

But if you believe that the amount of antenna the coil "replaces"
determines the differential, wouldn't this be true regardless of the
placement of the coil in the antenna?

I'll be constructing a more ideal
33 foot vertical in the near future, and making similar measurements at
3.8 MHz. So if its feedpoint impedance is, let's say, 35 - j370, what
would be the input to output current ratio (magnitude and phase) for a
physically very small base inductor of, say, +j300 ohms? If it's very
small, then pick an inductor value which would exhibit a substantial
input:output current ratio.


Are you going to insist that it be one of these ferrite core jobs, or is it
more like ones on a HF6V?

Is there something about a "ferrite job" that makes it follow different
rules? But the answer is no to both. I insist on using a physically
small toroid wound on a powdered iron core. Only after people understand
how a physically small inductor works will they have any chance of
understanding how a physically long one does.

Roy Lewallen, W7EL

Today's project was to construct and measure a more idealized antenna.

The antenna is 33 feet high, made of #16 insulated wire. I put out 23
radials on the surface of the wet ground. Radials were of various
lengths, most about 30 feet long. The feedpoint impedance of the
antenna, measured with a GR bridge, was 15.8 - j437 ohms at 3.8 MHz.
Allowing 3% lengthening effect for insulation, EZNEC says a lossless
vertical of that height and diameter should have an input Z of 7.5 -
j478. 8.3 ohms loss resistance is reasonable for that number of radials,
and the somewhat lower than predicted reactance is likely due to the
fact that the radial wires were grouped together as they came up a few
inches to the antenna base, and not immediately coming in contact with
the ground. That would add a bit of inductive reactance.

I wound an inductor on a T-106-6 core as before, but with more turns,
for a measured Z of 1.3 + j387 ohms. After putting it in series with the
antenna at the base, the base impedance measured 17.1 - j54 ohms. This
is only 4 ohms from the expected reactance, and spot on the expected
resistance, so measurements are consistent.

Analyzing verticals with EZNEC, made from #16 wire at 3.8 MHz, shows that:

-- An antenna 63.2' high is resonant.
-- An antenna 35.9' high has a feedpoint reactance of -j437 ohms.
-- An antenna 59.35' high has a feepoint reactance of -j54 ohms.

With a resonant height of 63.2', you could say that 63.2' is "90
electrical degrees" as far as the antenna is concerned. So you might say
that my inductor has "replaced 33.4 electrical degrees" of the antenna.

Using Yuri's cosine rule, we should then expect the inductor output
current to be cos(33.4 deg) times the input current, or 16.5% less.
Also, we should expect to see those 33 degrees of "replaced antenna" as
phase shift from the input to the output of the inductor. That is, the
current change from the input to output of the inductor is the same as
it would be for the portion of the antenna it "replaces". (I think Jim
Kelley subscribes to this theory also, but I'm not sure.)

In contrast, conventional electrical circuit theory predicts no current
difference between the input and output for a physically very small
inductor with no radiation or stray coupling. I saw about 3% in the
previous measurement, which I believe can be attributed to stray
capacitance. So I predicted that we should see about twice that amount
with the higher valued inductor used for this experiment (387 vs 192
ohms reactance). I didn't see any measurable phase shift between input
and output before, so I didn't expect to see it this time.

So for this test, there's quite a difference in predictions for
output:input current --

**Yuri's method predicts a reduction of output current magnitude of
16.5% and a phase shift of 33 degrees.

**I predict around 6% magnitude reduction (due to stray C) and no
measurable phase shift (less than 2 or 3 degrees).

I have very high confidence that my measurements are good enough to
resolve the difference between these two possibilities.

Would anyone care to comment before I post the measurement results? And,
Yuri, please correct me if I've misinterpreted your theory.

Roy Lewallen, W7EL

Roy, W7EL wrote:
"Can we make a physically small "phase reversing coil" that has 180
degree phase shift between its ends? If so, how?"

Yes. Kraus was discussing collinear arrays composed of 1/2-wave elements
interconnected by phase inverters to keep the currents in all elements
in-phase, that is, flowing in the same direction.

More than the phase delay of the coil is involved. Its self-capacitance
is involved in making a parallel resonant circuit at the operating
frequency.

The phase relations would be the same for a smaller inductance shunted
with a larger capacitance.

Two reasons for using self resonance; simplicity and wider bandwidth
with the low-C circuit.

These parallel resonant circuits replace short-circuit 1/4-wave stubs in
some collinears.

Best regards, Richard Harrison, KB5WZI

I apologize if the reason for my delay in posting measurement results is
seen as being to embarrass people. That's not at all the purpose. The
intent is simply to force people to make numerical predictions based on
their theories, rather than explaining the results after the fact. As it
turns out, Yuri is the only one confident enough of his theory to make a
numerical prediction(*). I happen to believe it's wrong, but by making
it he's earned my respect. A theory can be tested only if it predicts
results which can be tested. Whether it turns out to be right or wrong,
we learn from it. Those who've waffled and dodged the issue aren't in my
opinion worthy of the respect Yuri is.

When all this is done, I hope that readers come away with some assurance
that circuit theory does work and can be applied to antenna problems --
provided that the assumptions made for the components are valid. If all
that's taken away is a feeling that I've been doing this to try and
embarrass people, then it's been worse even than a monumental waste of
time. I really did have other things I wanted to do today besides make
antenna measurements, and I spent the time doing it only in the hope
that it would open some eyes.

Roy Lewallen, W7EL

(*) I've really solicited predictions only from people who don't agree
with conventional circuit theory, and believe that there will be a
difference in current from input to output. So there are also a number
of people who agree with me that conventional circuit theory holds, but
haven't explicitly made a prediction.

Richard Clark wrote:
. . .
But such is the gamesmanship that is being conducted, from the start.
The withholding of data to embarrass correspondents is not uncommon.
Lord knows how many I've embarrassed with simpler topics (the current
crew being only a subset). However, I generally restrain my
participation such that those threads are smaller. Otherwise the
posting of:
. . .

Reg Edwards wrote:
A design which 'exceeds' specified performance is as poor as one which
'under exceeds'.

It would have cost money and space to add the circuits to bring the
measurable jitter up to the RS232 specification allowable threshold.
You really think I should have done that?
--
73, Cecil http://www.qsl.net/w5dxp



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Roy Lewallen wrote:
Now, that's quite an insult, based on a total lack of information about
my career and what I've accomplished.

Why is it OK for you to insult my engineering capabilities but not
vice versa? How does it feel?

I'm going to do my best to ignore Cecil's postings from here on. They're
abusive and insulting.

Yours were abusive and insulting first and second. I did this one just
to let you know how your insults feel. If you will stop saying
things to me like, "I am continually amazed at how truly ignorant
some engineers are ...", I will not feel the need to retaliate.
--
73, Cecil http://www.qsl.net/w5dxp



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Roy Lewallen wrote:
Can we make a physically small "phase reversing coil" that has 180
degree phase shift between its ends? If so, how?

Why are you so hung up on physically small coils? The subject is
center-loading coils on mobile antennas, like bugcatchers.
--
73, Cecil http://www.qsl.net/w5dxp



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Roy Lewallen wrote:
When all this is done, I hope that readers come away with some assurance
that circuit theory does work and can be applied to antenna problems --
provided that the assumptions made for the components are valid.

Roy, isn't everything moot after Kraus tells us that an antenna coil
can cause a 180 degree phase reversal? Plus his graph of current in
a loaded antenna that shows a step function in the current at the
loading coils? The entire purpose of this discussion was to determine
if the following statement, allegedly made by W8JI, is true or false.

"This is in any book, including the ARRL Handbook. If you look at HOW
an inductor works, the current flowing in one terminal ALWAYS equals
the current flowing out the other terminal."

That's the very clear statement that was questioned by Yuri. And you
have already proved it not to be true even with your toroidal coil.

Incidentally, given a 180 degree phase reversing coil, the current
is flowing into both ends at the same time.
--
73, Cecil http://www.qsl.net/w5dxp



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Would anyone care to comment before I post the measurement results? And,
Yuri, please correct me if I've misinterpreted your theory.

Roy Lewallen, W7EL



It is not my theory. My argument with W8JI and his followers: is the current in
typical loading coil in quarter wave radiator same at both ends or does it drop
with distance from the feedpoint. I have made temperature observations, W9UCW
measured the difference, W5DXP provided some explanation. Based on Cecils
analysis of data you provided, and on my understanding of the phenomena I
guestimated drop in current in your setup. No theory, no mathematical procedure
(yet) just attempt (using degrees replaced by coil in a radiator) at
explanation of what is happening. I will measure things myself, try to verify
previous measurements and then come up with conclusions and "theory". So far
Cecils (and ON4UN book) theory seems to be closest to the truth.

As far as your measurements, it appears that you are trying to use the worse
case extreme situation (feed point, toroid) to prove your case. Why don't you
use thermo ammeters or current probe without leads and normal coil and do it on
typical mobile whip antenna.
Here is the info on homebrew current probe:
http://www.isd.net/~lyle/currprob/currprob.htm

I am going to build one too, it is handy to check the current while sliding
along the radiator, which easier than inserting ammeter.

I posted my 7 points, so far not one argument against, had few agreements.

What's this guessing game anyway? Why don't you try to prove that W9UCW
measurements are off the rocker?

Yuri, K3BU

A design which 'exceeds' specified performance is as poor as one which
'under exceeds'.

Significant deviations in either direction are sure indications of poor
engineering education and incompetence.

Both deviations are equally expensive and wasteful in terms of time,
materials and labour.



Now that is some "wisdom" coming out of FGQ think tank :-)
All the briliant engineers and inventors? Shame on you!
You come up with better and cheaper solution, you are incompetent!
(must be union mentality)

BUm

Ok,

For anyone who cares, the magnitude of the current out of the inductor
in the later test measured 5.4% less than the current in. No phase shift
was discernible. An analytical person could build on this information to
investigate the properties of longer inductors placed elsewhere in the
antenna.

Thank you for the comments, Cecil, Yuri, Richards, Art, and others. I've
learned a good lesson from this -- that this isn't an appropriate forum
or appropriate audience for the sort of quantitative analysis and
reasoning I'm familiar and comfortable with. And that the considerable
time and effort required to make careful measurements is really of very
little benefit -- certainly not anywhere near enough to justify it.

With a great sigh of relief from everyone, I'm sure, I'll now turn this
thread back over to Yuri, Cecil, et al.

My apologies to everyone for taking up so much bandwidth.

73,
Roy Lewallen, W7EL

Yuri Blanarovich wrote:
Would anyone care to comment before I post the measurement results? And,
Yuri, please correct me if I've misinterpreted your theory.

Roy Lewallen, W7EL




It is not my theory. My argument with W8JI and his followers: is the current in
typical loading coil in quarter wave radiator same at both ends or does it drop
with distance from the feedpoint. I have made temperature observations, W9UCW
measured the difference, W5DXP provided some explanation. Based on Cecils
analysis of data you provided, and on my understanding of the phenomena I
guestimated drop in current in your setup. No theory, no mathematical procedure
(yet) just attempt (using degrees replaced by coil in a radiator) at
explanation of what is happening. I will measure things myself, try to verify
previous measurements and then come up with conclusions and "theory". So far
Cecils (and ON4UN book) theory seems to be closest to the truth.

As far as your measurements, it appears that you are trying to use the worse
case extreme situation (feed point, toroid) to prove your case. Why don't you
use thermo ammeters or current probe without leads and normal coil and do it on
typical mobile whip antenna.
Here is the info on homebrew current probe:
http://www.isd.net/~lyle/currprob/currprob.htm

I am going to build one too, it is handy to check the current while sliding
along the radiator, which easier than inserting ammeter.

I posted my 7 points, so far not one argument against, had few agreements.

What's this guessing game anyway? Why don't you try to prove that W9UCW
measurements are off the rocker?

Yuri, K3BU

Yuri Blanarovich wrote:
What's this guessing game anyway?

If you can talk an astronomer into predicting the day in 2004 when
the first level 3 solar storm will hit earth, you can discredit him
when his prediction falls through.
--
73, Cecil http://www.qsl.net/w5dxp



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Roy Lewallen wrote:
Now, that's quite an insult, based on a total lack of information about
my career and what I've accomplished.


Cecil wrote:
Why is it OK for you to insult my engineering capabilities but not
vice versa? How does it feel?


I wrote:
Ditto happened to me, started with W8JI (they can do that) but when I responded
in kind, they don't like it and the cultists join in choir, defending their
favorite "guru", ignoring the facts.
If it works on transmit, it should work on receive too :-)

I mentioned on the outset, if we can exchange arguments in a civil manner, I am
for it and will respond in kind, but when someone pulls out ridicule, snotty
remarks and insults, then the gloves are off.
As the famous King said: "Can we all get along?"

Yuri

Roy Lewallen wrote:
For anyone who cares, the magnitude of the current out of the inductor
in the later test measured 5.4% less than the current in. No phase shift
was discernible.

A better way to measure phase shift is to measure the delay between
the zero-crossings of the two currents.
--
73, Cecil http://www.qsl.net/w5dxp



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or approximately 22 inches per division...at the speed of light.

"Cecil Moore" wrote in message
...
Roy Lewallen wrote:
If the small inductor
shows a measureable phase shift from input to output, I'll be just as
wrong as I'll be if it shows a magnitude change.

And if the small inductor shows a phase shift too small to be
measured, you will have invented faster than light transmission
because inches per nanosecond is easy to measure nowadays. Heck,
my old bench scope will display two nanoseconds per division.
--
73, Cecil http://www.qsl.net/w5dxp



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Yuri Blanarovich wrote:
I mentioned on the outset, if we can exchange arguments in a civil manner, I am
for it and will respond in kind, but when someone pulls out ridicule, snotty
remarks and insults, then the gloves are off.

It gets downright aggravating to hear over and over just how competent the
guru side is compared to the other (implied) ignorant side (as if gurus
cannot possibly be wrong).
--
73, Cecil http://www.qsl.net/w5dxp



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w4jle wrote:
or approximately 22 inches per division...at the speed of light.

Hard to believe RF can propagate through a coil faster than that, eh?
--
73, Cecil http://www.qsl.net/w5dxp



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If it is proved that the coil works differently than my assumptions, will my
radio stop working?

Why bother with an expensive loading coil if nothing changes through it? I
may as well take down my bug catcher and replace it with a hunk of pipe.
That way I can put an even bigger capacitance hat on it.

I am resuming the count of pirouetting angels...If only the darn pin would
quit sticking me!

"Cecil Moore" wrote in message
...
w4jle wrote:
or approximately 22 inches per division...at the speed of light.

Hard to believe RF can propagate through a coil faster than that, eh?
--
73, Cecil http://www.qsl.net/w5dxp



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Roy, W7EL wrote:
"When all this is done, I hope that readers come away with some
assurance that circuit theory does work and can be applied to antenna
problems -- provided that the assumotions made for the components are
valid."

Yes. And, there is another proviso. The reflected energy must be
considered along with the incident energy. Antenna problems are
relatives of transmission line problems.

Terman wrote of impedance in a transmission line with a reflection:
"When a reflected wave is present, the impedance will be alternately
greater and lower than the characteristic impedance, as illustrated in
Fig. 4-10."

This is also true of standing-wave antennas but is complicated by r-f
radiation from the antenna.

Early in this thread, I gave the example of W5LIT`s mobile antenna which
was all coil. It was a bamboo pole wound end to end with wire. At the
feed end its impedance was low. Approximately 90-degrees away at the tip
end, impedance was very high as indicated by the corona often produced
by the high voltage.

The current at the tip end was much less than at the feed point. The
ARRL Antenna Book shows how this can happen in Fig 6 on page 16-4 of the
19th edition.

I admire and appreciate Roy`s experimental verification of antenna
speculations and predictions. Until demonstrated, theory is only theory
and all such explanations are not necessarily so.

Best regards, Richard Harrison, KB5WZI