But....Just using my built in
"BS" filter only, which rarely seems to fails me, and ignoring all
other influences, I still have to side with Tom. I still think the
current is fairly constant.

Nothing
personal either way...But I have learned never to ignore my BS filter,
so I'm going with it. MK


Same here,
did your filter filtered out W5DXP pudding? The "theoretical" proof is right
there. Or are you drinking the same coolaide as Tom? :-)

Yuri

Reality vs. Speculations? Duuuh?

Yuri Blanarovich wrote:
Same here,
did your filter filtered out W5DXP pudding? The "theoretical" proof is right
there. Or are you drinking the same coolaide as Tom? :-)

Yuri, my latest posting sheds more light. Apparently, W8JI doesn't
realize that there are two superposing currents phasor-adding together
to get the net current and the phase distribution between those two
current waves are opposite because they are traveling in opposite
directions. This is a characteristic of standing-wave antennas.

See what happens when one tries to ignore the component waves?

Because the two currents are traveling in opposite directions, any phase
delay through the coil shifts the phase of the two currents IN OPPOSITE
DIRECTIONS. Thus the total relative phase shift effect through a 10 degree
coil is 20 degrees.
--
73, Cecil http://www.qsl.net/w5dxp



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oSaddam (Yuri Blanarovich) wrote in message ...
But....Just using my built in
"BS" filter only, which rarely seems to fails me, and ignoring all
other influences, I still have to side with Tom. I still think the
current is fairly constant.

Nothing
personal either way...But I have learned never to ignore my BS filter,
so I'm going with it. MK


Same here,
did your filter filtered out W5DXP pudding? The "theoretical" proof is right
there. Or are you drinking the same coolaide as Tom? :-)

Yuri

Reality vs. Speculations? Duuuh?''

Oh, purely speculation on my part. I have no easy way of really
knowing the reality. There is a small part that keeps bugging me, but
I'd have to see for sure where he is measuring the currents. I missed
the pix on the site. I'll assume for now he measured at each end of
the coil, pretty much at the connection to the mast or whip. The part
the bugs me is a possible stunting of the current at the top of the
coil due to the capacitance it is looking at, at the end of the coil.
To my thinking, once you leave the coil, even right at the end, you
should see a reduction of current, compared to say even a turn or two
from the top of the coil. I'm just wondering if this may be giving a
false indication of the true currents within the coil,if he is
measuring slightly outside of the coil. I'd be more satisfied if he
could measure a few turns from each end "using a large, many turns,
coil for 80 or 160" to get a general view within the windings
themselves. But I realize this could be very difficult. You all may be
totally correct. I'd just like to be a little better convinced before
I totally agree. I expect a slight decrease in current at the top vs
bottom. But I don't expect it to be large. I also don't expect the
bottom of the coil to be "hot", with a radical current taper on the
upper windings. The main thing I see to causing a reduction of
current , is the stinger on top of the coil. "capacitance" I wonder if
he is seeing the effects of that capacitance in his lower measurement?
Only the shadow knows for sure....:/
As far as the reverse currents Cecil mentions, I'd have to ponder that
a while.
Seems to me that could wildly vary from antenna to antenna depending
on height, coil positions, any top loading, etc..Although it looks
good on paper, I smell a hook. So I'd have to think about that more.
BTW, this amount of current in the coil, is something I've also
thought about myself. I've just come to the "different" conclusion
it's fairly constant through the coil. I could always be wrong.
Wouldn't be the first time.. But I need to see/hear a bit more to be
convinced. MK

Radio amateurs and just as many professionals suffer from delusions of
accuracy where RF measurements are concerned.

Especially HF current and power measurememts.

Far too much importance is attached to names like GR and HP and Fluke rather
than their own abilitity to assess and sum the accumulation of measuring
errors.

--
=======================
Regards from Reg, G4FGQ
For Free Radio Design Software
go to http://www.g4fgq.com
=======================
"Mark Keith" wrote in message
om...
oSaddam (Yuri Blanarovich) wrote in message
...
But....Just using my built in
"BS" filter only, which rarely seems to fails me, and ignoring all
other influences, I still have to side with Tom. I still think the
current is fairly constant.

Nothing
personal either way...But I have learned never to ignore my BS filter,
so I'm going with it. MK


Same here,
did your filter filtered out W5DXP pudding? The "theoretical" proof is
right
there. Or are you drinking the same coolaide as Tom? :-)

Yuri

Reality vs. Speculations? Duuuh?''

Oh, purely speculation on my part. I have no easy way of really
knowing the reality. There is a small part that keeps bugging me, but
I'd have to see for sure where he is measuring the currents. I missed
the pix on the site. I'll assume for now he measured at each end of
the coil, pretty much at the connection to the mast or whip. The part
the bugs me is a possible stunting of the current at the top of the
coil due to the capacitance it is looking at, at the end of the coil.
To my thinking, once you leave the coil, even right at the end, you
should see a reduction of current, compared to say even a turn or two
from the top of the coil. I'm just wondering if this may be giving a
false indication of the true currents within the coil,if he is
measuring slightly outside of the coil. I'd be more satisfied if he
could measure a few turns from each end "using a large, many turns,
coil for 80 or 160" to get a general view within the windings
themselves. But I realize this could be very difficult. You all may be
totally correct. I'd just like to be a little better convinced before
I totally agree. I expect a slight decrease in current at the top vs
bottom. But I don't expect it to be large. I also don't expect the
bottom of the coil to be "hot", with a radical current taper on the
upper windings. The main thing I see to causing a reduction of
current , is the stinger on top of the coil. "capacitance" I wonder if
he is seeing the effects of that capacitance in his lower measurement?
Only the shadow knows for sure....:/
As far as the reverse currents Cecil mentions, I'd have to ponder that
a while.
Seems to me that could wildly vary from antenna to antenna depending
on height, coil positions, any top loading, etc..Although it looks
good on paper, I smell a hook. So I'd have to think about that more.
BTW, this amount of current in the coil, is something I've also
thought about myself. I've just come to the "different" conclusion
it's fairly constant through the coil. I could always be wrong.
Wouldn't be the first time.. But I need to see/hear a bit more to be
convinced. MK

Reg finally figured it out:

Radio amateurs and just as many professionals suffer from delusions of
accuracy where RF measurements are concerned.

Especially HF current and power measurememts.

Far too much importance is attached to names like GR and HP and Fluke rather
than their own abilitity to assess and sum the accumulation of measuring
errors.

Thank goodness we have your formulas, failproof programs and variety of
speculations. Gentlemen, case is solved, closed. We can't measure it, we are
all bunch of dumb delusional morons with faulty instruments who don't know how
to use them. Current must be the same in the coil according to Rauch, Kirchoff,
Ohm, Reg. So now make your antennas out of coils, you will have constant
current radiator tip to tip with 300% efficiency and you can throw your
instruments away. Reg has the formula for it, use it!

Seriously, I thank you Cecil, Fred and few others who enlightened our case,
that's what I was hoping for and found it here. It will be the springboard for
further development, it already gave me some ideas how to improve efficiency of
loaded aerials. The others from the flat earth society showed their colors and
they ain't pretty. Just like democRATs, when they are deficient in arguments
they triviliarize and ridicule.
We are planning mobile antenna shootout here on east coast in the spring, so
get your wares ready and see who is da king koil.

Yuri, da BU/m

Yuri Blanarovich wrote:
Current must be the same in the coil according to Rauch, Kirchoff,
Ohm, Reg.

Kirchhoff and Ohm were not wrong. For a lossless coil, the forward current
magnitude must be the same in the coil and the reflected current magnitude
must be the same in the coil. But the net current is the sum of those two
component waves which have phase angles rotating in opposite directions.
The basic problem is using lumped circuit calculations for a distributed
network problem, a well known no-no.
--
73, Cecil http://www.qsl.net/w5dxp



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Mark Keith wrote:
As far as the reverse currents Cecil mentions, I'd have to ponder that
a while.

While you are pondering, here is a quote from _Antenna_Theory_, by Balanis.

"Standing wave antennas, such as the dipole, can be analyzed as traveling
wave antennas with waves propagating in opposite directions (forward and
backward) and represented by traveling wave currents 'If' and 'Ib' in
Figure 10.1(a)."

Standing wave antennas necessarily have standing waves caused by forward
waves and reflected waves. Analyze any coil subjected to forward current
and reflected current and you will be forced to agree that the current
at one end of the coil is not the same as the current at the other end
of the coil. W8JI is thinking lumped circuits when he should be thinking
distributed networks. The phase shift through the coil changes the
phase relationship between the forward current and reflected current, so
of course, their superposed value will be different at each end of the coil.
--
73, Cecil http://www.qsl.net/w5dxp



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Cecil Moore wrote in message ...
Mark Keith wrote:
As far as the reverse currents Cecil mentions, I'd have to ponder that
a while.

While you are pondering, here is a quote from _Antenna_Theory_, by Balanis.

"Standing wave antennas, such as the dipole, can be analyzed as traveling
wave antennas with waves propagating in opposite directions (forward and
backward) and represented by traveling wave currents 'If' and 'Ib' in
Figure 10.1(a)."

Standing wave antennas necessarily have standing waves caused by forward
waves and reflected waves. Analyze any coil subjected to forward current
and reflected current and you will be forced to agree that the current
at one end of the coil is not the same as the current at the other end
of the coil. W8JI is thinking lumped circuits when he should be thinking
distributed networks. The phase shift through the coil changes the
phase relationship between the forward current and reflected current, so
of course, their superposed value will be different at each end of the coil.

How much though? What would be an average ratio difference you would
be likely to see on a 8 ft center loaded whip? Or lets go one
better...What would be a likely "worse case" scenario? Will this vary
from antenna to antenna? I would think so. I've never said there would
not be a difference. I actually expect a small difference. But I still
don't think it would be a large amount. Will this change in value be
enough to cause large errors in modeling these antennas? It's already
obvious to me that any info I may gleen from these tests will have no
impact on the position of my loading coils, being I already use them
at the optimum heights. Or as close as physically possible anyway. So
any info gleaned from these tests would only be useful from a modeling
aspect. And I'm not in a position to really comment on that too much.
I don't design modeling engines. Is it your opinion that the modeling
we now see with these antennas and coils is quite flawed? It's obvious
Yuri seems to think so. Myself, I really don't know at this point.
I've never worried about it too much. I don't model shorter than 1/4
wave verticals. MK

Mike,
the differences in current are in order of 40 - 60%, that is significant.
The lower the band, the shorter the antenna, the bigger the effect, the more
important where the coil is. It will vary from antenna to antenna, depending on
the coil "shortening" factor. If the coil is closer to the feedpoint, the
current difference is lees, but efficiency suffers most. As you move coil up
the radiator, turns increase, current difference increases and effciency goes
up. If you replace (part of) coil with top loading, current differences
decrease (0 difference at 0 deg. long coil) and your efficiency goes up.
Efficiency or radiated power of loaded antenna is roughly proportional to the
area under the corresponding current curve of the remaining (straight)
radiator. Coil "eats" part of the radiator and its current carrying (radiating)
capabilities, this is why the current will be significantly different at the
ends of the coil. I hope this illustrates the situation?

As Cecil showed, modeling is not accounting for the effect and now that Roy is
on, we hope to sort things out and come up with ways to best implement the
phenomena in modeling programs. Right now, it appears that the best way to
approximate the effect is to use loading stubs of the same inductance as
intended coil.

Barry and Cecil agreed to cooperate on the article describing in detail (and in
civil manner :-) this subject and we hope that Roy will join us adding the
modeling aspect to it.

Yuri, K3BU/m

Mark Keith wrote:
How much though? What would be an average ratio difference you would
be likely to see on a 8 ft center loaded whip?

A lot on 75m. Not much on 12m.

Or lets go one
better...What would be a likely "worse case" scenario?

The worse case I can think of is a short center-loaded whip
on 160m. :-) The coil is almost all of the necessary 1/4WL.

Will this vary from antenna to antenna? I would think so.

Of course. It is all capable of being calculated.

Is it your opinion that the modeling
we now see with these antennas and coils is quite flawed?

The antenna current reported by EZNEC is inaccurate because of
simplified assumptions. EZNEC assumes that the current doesn't
change through the single point inductive load. Therefore, EZNEC
cannot be used to prove that the current doesn't change.
--
73, Cecil http://www.qsl.net/w5dxp



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