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
inpututput current ratio.

Roy Lewallen, W7EL

"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
inpututput 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

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
inpututput 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

"Roy Lewallen" wrote in message
...

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.

The discussion is about 'long' inductors. You continue to try to steer the
discussion away from them. Why is that?

73, Jim AC6XG

"Roy Lewallen" wrote in message
...
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.

Perhaps the statement was poorly worded. The presumption is that the
"missing degrees" of length are supplied by the coil. Do you believe this
is untrue? Realize of course, that a sufficiently simple model can fail to
describe any phenomenon which has been oversimplified in the model.

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.

Yes, Roy. The discussion is limited to those coils which cause a current
differential from one end to the other. The other kind don't meet the
requirement. :-)

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?

No. Note the shape of the current vs position curve along the antenna. It
doesn't change linearly with position. There are relatively flat regions
near the ends, and there's region nearer the middle where the current
changes rapidly with position. Presumably it's related to the way the
impedance changes with position along the antenna.

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?

The 'ferrite jobs' provide considerably more inductance for a given coil
size. Fewer turns, shorter length of wire, physically smaller, no
radiation. Do you agree there's a difference between air and ferrite?

Only after people understand
how a physically small inductor works will they have any chance of
understanding how a physically long one does.

Which people are those, Roy?

73, Jim AC6XG

Jim Kelley wrote:
Perhaps the statement was poorly worded. The presumption is that the
"missing degrees" of length are supplied by the coil. Do you believe this
is untrue? Realize of course, that a sufficiently simple model can fail to
describe any phenomenon which has been oversimplified in the model.

Roy's measurements verify Yuri's predictions. Assuming 1.0 amps at zero
degrees on one side of the coil, 0.95 amps out is almost exactly 18 degrees
since arc-cos(0.95)=18.2 degrees. Am I missing something?
--
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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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

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

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