On Mon, 30 Apr 2007 06:37:10 -0500, "amdx" wrote:

Are you exploring an intellectual curiosity or trying to
remedy a defect in application?

No, I just have experienced the effect that Bill ask about and
gave my own pet theory about why it happens.
Now I'm looking for a little confirmation or where I went wrong.

Hi Mike,

Well, that is fine and good, but neither of you have given us any real
data, and certainly no Q values to judge if what you both experienced
was within the range of "normal" or out in left field. RF
measurements are difficult to do to any particularly fine accuracy,
and what was observed may have been simple variation due to the
measurer's proximity (offering just one of many things that can go
wrong).

Loss still remains the province of resistance.

Richard, That's like saying rain has water in it. No matter how many times
you say it,
I'm still going to agree with you.

Then this diverges from Bill's premise of Capacitance being the source
of loss and you and he are separable at this point of your common
experience.

Your best argument is that Capacitance exacerbates loss.

I would rephrase that as "interwinding capacitance exacerbates loss".

And with that, you have summed up my argument perfectly.

You have helped reduce my argument to 4 words.

Now, do you agree that interwinding capacitance will reduce Q?
(yes, I know it's the province of resistance)

Give me some metrics to show it is not skin effect.

The issue at hand is your (both you and Bill, or either of you
separately) loops keep changing to fit to the loss rather than to the
application. It makes for a rather strained progression of design as
loops are added, proximity becomes a greater issue, as coil length
collapses, insulation is added, and as frequency shifts to follow
these changes. It is as though a good 10M loop is evolving to operate
poorly there or, worse, in the 160M band where its resonance has
finally come to rest through optimizing for loss.

I can imagine there being enough turn-to-turn capacitance to induce
large currents, but so many correlating factors would have to ride
along with this that they could easily eclipse that contribution of
loss. In other words, it seems the goal of your argument is to raise
that capacitance, which by ordinary means has you drawing the loops
together (insulated or not). This compounds the skin effect and for a
constant frequency demands a lower inductance. The lower inductance,
in turn, then demands a smaller coil which forces a lower Radiation
resistance. A smaller coil (to again follow the demand for more
Capacitance) drives closer loops.

It seems like this is in an infinite regress.

73's
Richard Clark, KB7QHC

"Richard Clark" wrote in message
...
On Mon, 30 Apr 2007 06:37:10 -0500, "amdx" wrote:

Are you exploring an intellectual curiosity or trying to
remedy a defect in application?

No, I just have experienced the effect that Bill ask about and
gave my own pet theory about why it happens.
Now I'm looking for a little confirmation or where I went wrong.

Hi Mike,

Well, that is fine and good, but neither of you have given us any real
data, and certainly no Q values to judge if what you both experienced
was within the range of "normal" or out in left field. RF
measurements are difficult to do to any particularly fine accuracy,
and what was observed may have been simple variation due to the
measurer's proximity (offering just one of many things that can go
wrong).

Yes, RF measurements are difficult to do to any particularly fine
accuracy.
And I claim no great knowledge of how to minimize errors or even how to
recognize where they come from.


Loss still remains the province of resistance.

Richard, That's like saying rain has water in it. No matter how many times
you say it,
I'm still going to agree with you.

Then this diverges from Bill's premise of Capacitance being the source
of loss and you and he are separable at this point of your common
experience.

Your best argument is that Capacitance exacerbates loss.

I would rephrase that as "interwinding capacitance exacerbates loss".

And with that, you have summed up my argument perfectly.

You have helped reduce my argument to 4 words.

Now, do you agree that interwinding capacitance will reduce Q?
(yes, I know it's the province of resistance)

Give me some metrics to show it is not skin effect.

The issue at hand is your (both you and Bill, or either of you
separately) loops keep changing to fit to the loss rather than to the
application. It makes for a rather strained progression of design as
loops are added, proximity becomes a greater issue, as coil length
collapses, insulation is added, and as frequency shifts to follow
these changes. It is as though a good 10M loop is evolving to operate
poorly there or, worse, in the 160M band where its resonance has
finally come to rest through optimizing for loss.

My experience is limited to winding small inductors rather than
loop antennas.

I can imagine there being enough turn-to-turn capacitance to induce
large currents, but so many correlating factors would have to ride
along with this that they could easily eclipse that contribution of
loss. In other words, it seems the goal of your argument is to raise
that capacitance, which by ordinary means has you drawing the loops
together (insulated or not). This compounds the skin effect and for a
constant frequency demands a lower inductance. The lower inductance,
in turn, then demands a smaller coil which forces a lower Radiation
resistance. A smaller coil (to again follow the demand for more
Capacitance) drives closer loops.

It seems like this is in an infinite regress.

I don't understand why you think we want more interwinding capacitance,
We want less.
I will agree that the mechanics involved in trying to reduce interwinding
capacitance
will probably reduce proximity effects and so to seperate out any affect
from the
reduces interwinding capacitance would be difficult.
I need to go,
Later, thanks Richard

"amdx" wrote in message
...

"Richard Clark" wrote in message
...
On Mon, 30 Apr 2007 06:37:10 -0500, "amdx" wrote:

Are you exploring an intellectual curiosity or trying to
remedy a defect in application?

No, I just have experienced the effect that Bill ask about and
gave my own pet theory about why it happens.
Now I'm looking for a little confirmation or where I went wrong.

Hi Mike,

Well, that is fine and good, but neither of you have given us any real
data, and certainly no Q values to judge if what you both experienced
was within the range of "normal" or out in left field. RF
measurements are difficult to do to any particularly fine accuracy,
and what was observed may have been simple variation due to the
measurer's proximity (offering just one of many things that can go
wrong).

Yes, RF measurements are difficult to do to any particularly fine
accuracy.
And I claim no great knowledge of how to minimize errors or even how to
recognize where they come from.


Loss still remains the province of resistance.

Richard, That's like saying rain has water in it. No matter how many
times
you say it,
I'm still going to agree with you.

Then this diverges from Bill's premise of Capacitance being the source
of loss and you and he are separable at this point of your common
experience.

Your best argument is that Capacitance exacerbates loss.

I would rephrase that as "interwinding capacitance exacerbates loss".

And with that, you have summed up my argument perfectly.

You have helped reduce my argument to 4 words.

Now, do you agree that interwinding capacitance will reduce Q?
(yes, I know it's the province of resistance)

Give me some metrics to show it is not skin effect.

The issue at hand is your (both you and Bill, or either of you
separately) loops keep changing to fit to the loss rather than to the
application. It makes for a rather strained progression of design as
loops are added, proximity becomes a greater issue, as coil length
collapses, insulation is added, and as frequency shifts to follow
these changes. It is as though a good 10M loop is evolving to operate
poorly there or, worse, in the 160M band where its resonance has
finally come to rest through optimizing for loss.

My experience is limited to winding small inductors rather than
loop antennas.

I can imagine there being enough turn-to-turn capacitance to induce
large currents, but so many correlating factors would have to ride
along with this that they could easily eclipse that contribution of
loss. In other words, it seems the goal of your argument is to raise
that capacitance, which by ordinary means has you drawing the loops
together (insulated or not). This compounds the skin effect and for a
constant frequency demands a lower inductance. The lower inductance,
in turn, then demands a smaller coil which forces a lower Radiation
resistance. A smaller coil (to again follow the demand for more
Capacitance) drives closer loops.

It seems like this is in an infinite regress.

I don't understand why you think we want more interwinding capacitance,
We want less.
I will agree that the mechanics involved in trying to reduce interwinding
capacitance
will probably reduce proximity effects and so to seperate out any affect
from the
reduces interwinding capacitance would be difficult.
I need to go,
Later, thanks Richard


Ok, I'm back.
Richard, I was starting to lean towards proximity effect possibly causing
all of the affect we have been discussing, so I did some Googling. I kept
find the
same line " increased capacitance lowers Q" But, I think you agree that as
I said
above most efforts to reduce capacitance will also reduce proximity effect.
I ran across W8JI's page, he's usually pretty exacting in his wording, and
he says,

"Capacitance across any inductor carrying time-varying current increases
circulating
currents in the inductor, increasing loss while simultaneously reducing
system bandwidth."

snip "Anything that increases capacitance will reduce component Q"

He never mentions the correlation between interwinding capacitance and
proximity effect

These line were taken from;
http://www.w8ji.com/loading_inductors.htm

What do you think?
Mike

On Mon, 30 Apr 2007 18:30:40 -0500, "amdx" wrote:

Richard, I was starting to lean towards proximity effect possibly causing
all of the affect we have been discussing, so I did some Googling. I kept
find the
same line " increased capacitance lowers Q" But, I think you agree that as
I said
above most efforts to reduce capacitance will also reduce proximity effect.

Hi Mike,

Yup.

I ran across W8JI's page, he's usually pretty exacting in his wording, and
he says,

"Capacitance across any inductor carrying time-varying current increases
circulating
currents in the inductor, increasing loss while simultaneously reducing
system bandwidth."

Tom is also given to non-sequiturs. He polishes his page off with a
list of them such as "Optimum form factor varies with application." As
they used to say, if you want to send a message, call Western Union.

snip "Anything that increases capacitance will reduce component Q"

He never mentions the correlation between interwinding capacitance and
proximity effect

There is not much that can be taken to the bank about what is NOT
said.

The moral of this is standard Engineering practice: start with a goal
and design towards it.

73's
Richard Clark, KB7QHC

On Apr 29, 4:52 am, "amdx" wrote:
"Bill Bowden" wrote in message

oups.com... Does anyone know why the distributed winding capacitance of a loop
antenna, or any inductor, degrades the efficiency?

-Bill

Hi Bill.
I agree with your assertion that distributed winding capacitance
degrades efficiency.
My thoughts about this are ;
Assume a 10 turn loop, between each turn there is a capacitance,
so, you have a complete circuit, (L,C,R) there is current
flowing through this circuit that is not flowing through the entire 10
turn loop. (this happens in the other 9 turns also)
I think these extra currents flowing that don't make the entire 10
turn circuit increase the losses.

Anyone care to run with that, or explain it more clearly, or shoot it
down.

Mike


I think you are right. Good explanation.

-Bill

"Bill Bowden" wrote in message
ups.com...
On Apr 29, 4:52 am, "amdx" wrote:
"Bill Bowden" wrote in message

oups.com... Does
anyone know why the distributed winding capacitance of a loop
antenna, or any inductor, degrades the efficiency?

-Bill

Hi Bill.
I agree with your assertion that distributed winding capacitance
degrades efficiency.
My thoughts about this are ;
Assume a 10 turn loop, between each turn there is a capacitance,
so, you have a complete circuit, (L,C,R) there is current
flowing through this circuit that is not flowing through the entire 10
turn loop. (this happens in the other 9 turns also)
I think these extra currents flowing that don't make the entire 10
turn circuit increase the losses.

Anyone care to run with that, or explain it more clearly, or shoot it
down.

Mike


I think you are right. Good explanation.

-Bill

Well Bill, That has been the theory I've been thinking with for 8 or 9
years now. However, if as Richard suggests the phenomena is caused
by proximity effect, the techniques I used to lower interwinding capacitance
and raise Q, would be the same I'd use to reduce proximity efect and raise
Q.
If there are circuilating currents caused by interwinding capacitance, it
seems
they would cause the proximity effect to be even stronger and pinch down the
current flow area even more and raise losses.

A question for all,
Does a basketweave winding reduce proximity effect?
Mike

Bill Bowden wrote:
"Does anyone know why the distributed winding capacitance of a loop
antenna, or any inductor, degrades the efficiency?"

I`ll speculate that current to build the magnetic field and the current
required to charge the stray capacitance of the inductor occur at
different times. The magnetic field is the source of self-inductance of
the coil, but the displacemnt current in the stray capactance is
gratuitous and only adds loss to the coil.

Best regards, Richard Harrison, KB5WZI

Distributed capacitance may affect single-turn coils differently from
multiturn-coils. And those vary as their length to diameter ratio
varies.

Mike wrote:
"Anything that increases capacitance will reduce component Q. I believe
he was quoting W8JI.

Mike also wrote:
"What do you think?"

In 1999 Tom Bruhns was experimenting, trying to find the relationship
between coil Q and parasitic C. He picked up reports that helical
resonators weere superior to short coaxial resonators. Tom also wrote:
"Reg (Edwards,RJE) then thinks the internal coil capacitance is just
femanding extra extra coil current and loss as the result of its cyclic
charge and discharge."

Reg seems to have had a nice explanation for coil loss from parasitic
capacitance.

Best regards, Richard Harrison, KB5WZI

"Richard Harrison" wrote in message
...
Distributed capacitance may affect single-turn coils differently from
multiturn-coils. And those vary as their length to diameter ratio
varies.

Mike wrote:
"Anything that increases capacitance will reduce component Q. I believe
he was quoting W8JI.

Mike also wrote:
"What do you think?"

In 1999 Tom Bruhns was experimenting, trying to find the relationship
between coil Q and parasitic C. He picked up reports that helical
resonators weere superior to short coaxial resonators. Tom also wrote:
"Reg (Edwards,RJE) then thinks the internal coil capacitance is just
femanding extra extra coil current and loss as the result of its cyclic
charge and discharge."

Reg seems to have had a nice explanation for coil loss from parasitic
capacitance.

Do you know where this explanation might be found?

Thanks, Mike

amdx wrote:
Do you know where this explanation might be found?

From "Current through coils", March 5, 2006 2:47pm
Looks like Reg originated this thread.

"Every coil has length. Both L and C are distributed. Therefore the
coil behaves as a transmission line. There are standing waves. Current
and voltage both vary with length."

And on March 9:

"The whole thing could be summarised in one short sentence -

'Coils are distributed transmission lines.'

The same general equations apply to coils of all dimensions, for any
number of turns, at all frequencies, in all applications. There's no
need to unnecessarily complicate things by artificially dividing them
into lumped and other varieties."
--
73, Cecil http://www.w5dxp.com