Phase Shift through a 75m Texas Bugcatcher Coil
 

Jim Kelley wrote:
As a suggestion, you might consider increasing the current for the EZNEC
simulation on your webpage. At 20 amps per division it's plus or minus
a pixel at 1024x768.

Excellent suggestion, Jim. I'm sure there is a way to do that
within the EXCEL charting function but, so far, I haven't figured
out how to split the scales. I was going to mow the yard but it's
92 degrees out there and I would rather play with EZNEC anyway.
--
73, Cecil http://www.w5dxp.com

Phase Shift through a 75m Texas Bugcatcher Coil
 

Jim Kelley wrote:
As a suggestion, you might consider increasing the current for the EZNEC
simulation on your webpage.

Done as you suggested by changing the current amplitude scale.
What do you think about the simulation? Stand by for more
additions to that web page.
--
73, Cecil http://www.w5dxp.com

Phase Shift through a 75m Texas Bugcatcher Coil
 

Cecil Moore wrote:

Jim Kelley wrote:

As a suggestion, you might consider increasing the current for the
EZNEC simulation on your webpage.


Done as you suggested by changing the current amplitude scale.
What do you think about the simulation? Stand by for more
additions to that web page.

From what I gathered, the objective of loading the coil with its
characteristic impedance was that there would be no reflection. I was
therefore surprised when you reported something other than a straight
line for the current amplitude along the radiator (let alone an
increase at some point). It is now apparent that what you are
actually plotting is the superposed forward and reflected currents,
and that you have somewhat more than a negligible amount of reflected
current.

The primary utility in looking at the standing wave profile lies in
the fact that it gives an idea of what the superposed field intensity
plot might look like in the near field of the antenna. But it is
obviously the currents associated with waves traveling on the antenna,
both forward and reflected, that actually do the radiating.

I agree with you that it is useful to understand the exact effect the
loading coil has on the traveling wave, and hence the standing wave
profile of the antenna. But I still think it would be prudent to
explore and understand the precise nature of the delay through the
coil more thoroughly before making too many assumptions about this.

73, Jim AC6XG

Phase Shift through a 75m Texas Bugcatcher Coil
 

Jim Kelley wrote:
I was
therefore surprised when you reported something other than a straight
line for the current amplitude along the radiator (let alone an increase
at some point).

Just proves that you are not omniscient. Such is the nature
of a real world inductance especially close to self-resonance.
This is just evidence of another failure of lumped inductance
models. The current through a real-world inductance is NOT
linear if the operating frequency is within 15% of the self-
resonant frequency. For the Nth time, please read and
understand the IEEE white paper at:

http://www.ttr.com/TELSIKS2001-MASTER-1.pdf
--
73, Cecil http://www.w5dxp.com

Phase Shift through a 75m Texas Bugcatcher Coil
 

Cecil Moore wrote:

Jim Kelley wrote:

I was therefore surprised when you reported something other than a
straight line for the current amplitude along the radiator (let alone
an increase at some point).


Just proves that you are not omniscient.

I doubt that proof of that is actually required. In fact, I think
you'll find that to be true in general for other people as well.


For the Nth time, please read and
understand the IEEE white paper at:

http://www.ttr.com/TELSIKS2001-MASTER-1.pdf

University of Yugoslavia. Yeah, sure thing. Whether it's valid or
not, I'm not convinced that's what you have in your EZNEC printout.
And unless Roy accounts for "current pileup", it's unlikely that it
would show up there.

73, AC6XG

Phase Shift through a 75m Texas Bugcatcher Coil
 

"Jim Kelley" wrote in message
...

University of Yugoslavia. Yeah, sure thing. .....

What's that supposed to mean?
If it is not overpriced American Liberal Alma Mater then is "Yeah"????

Nikola Tesla did more for the mankind than anyone produced by US colleges.
Quite an insult to thousands of Slavic engineers immigrants who built IBMs,
GMs, etc.

Can we discuss technical matters or rather play know-it-alls gurus?
Can you point out what is wrong with that paper?

73 Yuri, oK3BU

Phase Shift through a 75m Texas Bugcatcher Coil
 

Cecil, W5DXP wrote:
"No, just that phasing of RF signals is what is confusing the DC gurus,
just like AC phasing confused Edison."

In W8JI`s pages I found this on the subject of "Mobile antennas, short
verticals, loading" :
It`s long and Tom warns about taking anything from context, so it should
be searched out and read in its entirety. I have no quarrel with most of
Tom`s pages but find this statement curious:
"When current flows in the transmitter-end of the coil, a magnetic field
is created. The time-varying magnetic field causes charges in the other
turns to instantly move."

Instant movement of charges is instant current, and everyone knows that
current in a coil lags the voltage.

Best regards, Richard Harrison, KB5WZI

Phase Shift through a 75m Texas Bugcatcher Coil
 

Richard Harrison wrote:
"When current flows in the transmitter-end of the coil, a magnetic field
is created. The time-varying magnetic field causes charges in the other
turns to instantly move."

Instant movement of charges is instant current, and everyone knows that
current in a coil lags the voltage.

Instant movement of charges is impossible except in the mind
of someone using the lumped-element model. Apparently, anything
is possible in that kind of mind. As Dr. Corum said: "Lumped
circuit theory fails because it's a *theory* whose presuppositions
are inadequate. Every EE in the world was warned of this in their
first sophomore circuits course. ... Lumped circuit theory isn't
absolute truth, it's only an analytical *theory* - and in those
resonators we have the case where this sophomore *theory* fails
*experimentally. The engineer must either use Maxwell's equations
or distributed elements to model reality."
--
73, Cecil http://www.w5dxp.com

Phase Shift through a 75m Texas Bugcatcher Coil
 

Richard Harrison wrote:
Cecil, W5DXP wrote:
"No, just that phasing of RF signals is what is confusing the DC gurus,
just like AC phasing confused Edison."

In W8JI`s pages I found this on the subject of "Mobile antennas, short
verticals, loading" :
It`s long and Tom warns about taking anything from context, so it should
be searched out and read in its entirety. I have no quarrel with most of
Tom`s pages but find this statement curious:
"When current flows in the transmitter-end of the coil, a magnetic field
is created. The time-varying magnetic field causes charges in the other
turns to instantly move."

Instant movement of charges is instant current, and everyone knows that
current in a coil lags the voltage.

Best regards, Richard Harrison, KB5WZI


Richard,

This is one of those situations where the exact definitions are
critical. In the case of "current lags voltage" the current is measured
through the coil and the voltage is measured between the ends of the coil.

The voltage at the input of the coil (to some reference point) is not
important; only the voltage across the coil matters. Since there is
nothing in the problem statement about the coil output voltage it is not
possible to determine if there is any violation of "current lags
voltage" or not.

I am not saying anything about the assertion from W8JI. The "current
lags voltage" principle simply does not settle anything in this case.

73,
Gene
W4SZ

Phase Shift through a 75m Texas Bugcatcher Coil
 

On May 7, 7:26 pm, "Yuri Blanarovich" wrote:
"Jim Kelley" wrote in message

If it is not overpriced American Liberal Alma Mater then is "Yeah"????

You make a good point.

Nikola Tesla did more for the mankind than anyone produced by US colleges.

Let's not get carried away. And I don't think Tesla was from
Yugoslavia.

Quite an insult to thousands of Slavic engineers immigrants who built IBMs,
GMs, etc.

No insult to them was ever intended. They didn't write the paper by
any chance....??

Can we discuss technical matters or rather play know-it-alls gurus?
Can you point out what is wrong with that paper?

I wish I understood this obsession you and Cecil have with gurus. I
don't share it.

About the paper; do you believe everything you read in the papers?
As I said, whether it is correct or not, I don't think it is
illustrated in Cecil's EZNEC printout.

73, Jim AC6XG