Loading Coils; was : Vincent antenna
 

Owen Duffy wrote:
It seems reasonable that a stand alone coil can be characterised as a
transmission line having a delay that equates to an electrical length in
degrees, radians, wavelengths or a velocity factor. In fact the
inductance calculator at http://hamwaves.com/antennas/inductance.html is
based on that approach and shows the calculated value of Beta.

But, but, but, Owen, the first reference in that web page
is the very Corum IEEE paper that I referenced that has
been completely and totally debunked by most of the gurus
on this newsgroup.
--
73, Cecil http://www.w5dxp.com

Loading Coils; was : Vincent antenna
 

Ian White GM3SEK wrote:
My apologies to AI4QJ. He was talking about a parallel R-L circuit, and
my reply was about a series R-L circuit. Each of our statements was
correct in its own context.

Sorry, but your statement is still incorrect. In a
traveling-wave circuit, the current phase varies
every inch along the circuit path. If it didn't,
rhombic antennas wouldn't work.
--
73, Cecil http://www.w5dxp.com

Loading Coils; was : Vincent antenna
 

Cecil Moore wrote:
Gene Fuller wrote:
As far as I can tell, W8JI did not do any math or other type of
analysis to come up with the 3 ns delay. There was some surrounding
discussion, but the delay itself was simply read from an instrument.
So let me repeat my earlier questions.

I previously answered your question in capital letters.

What went wrong? Why is that number incorrect?

This is about the 20th time that I have explained the error
that W8JI made. The signal he used to measure phase shift
didn't possess a phase shift. W7EL made the same mistake in
his "delay through a loading coil" measurements. When the
phase of the total current changes hardly at all from one
end of a 1/2WL dipole to the other, that current CANNOT even
be used to measure the delay through the wire. Why do you,
W8JI, and W7EL think a current with an essentially unchanging
phase can be used to measure phase shift? This is all explained
on my web page.

And for the 21st time, we are talking about delay, not phase shift. That
point seems difficult for you to fathom.

One of the reasons this entire issue goes on and on is that the
terminology is a bit foggier than it might first appear. The
revolutionary Corum "n=0 sheath helix waveguide mode" is derived for a
single frequency in steady-state conditions. So how does one even define
"delay" under that condition? If you add some sort of marker signal, the
measurement of "delay" will be for the propagation of that marker
signal, not the original underlying steady-state wave.

By the way, Corum does not mention delay at all, with one minor exception.

73,
Gene
W4SZ

Loading Coils; was : Vincent antenna
 

Owen Duffy wrote:

[snip]


If you use the inductance calculator at
http://hamwaves.com/antennas/inductance.html to determine Beta, you get
2.008 rad/m. The coil is .254m long, so that suggests a one-way phase
delay of 0.51 rad, or 29.2°. Some suggest that this coil will replace the
equivalent electrical length in a quarter wave monopole to shorten it
with inductive loading, and irrespective of the position of the loading
coil... which is not consistent with experience that a larger loading
coil is needed the further it is from the base.



Something to consider about the Hamwaves calculator. This Corum
calculation appears to analyze everything in terms of the "n=0 sheath
helix waveguide mode", whether it is appropriate or not. This web page
does not contain any of the caveats that were in the Telsiks article.
Try some extreme numbers and you can see that the expected results do
not occur.

It is somewhat ironic that the work of David Knight, referenced by
Corum, appears to refute quite of bit of Corum's claim. Knight
recognizes, as many people do, that there is a transition between a
lumped model regime and the quarter wave resonance regime. The resonance
model does not apply when the coil is shorter or the frequency is lower.

73,
Gene
W4SZ

Loading Coils; was : Vincent antenna
 

Gene Fuller wrote:
And for the 21st time, we are talking about delay, not phase shift. That
point seems difficult for you to fathom.

They are related in a traveling-wave environment. They are
virtually unrelated in a standing-wave environment. W8JI
asserts that the delay through a 100T coil at 4 MHz is
3 ns which is impossible. If he had asserted that the
standing-wave current undergoes a 4.5 degree phase shift
through that coil, we wouldn't be having this argument
because the phase of standing-wave current is virtually
constant over the length of a 1/2WL dipole. At the ends
of a dipole longer than 1/2WL, it does an abrupt 180 degree
phase shift. W8JI and W7EL seem to be totally ignorant of
that fact of physics since they both tried to use standing-
wave current to "measure" phase-shift/delay.
--
73, Cecil http://www.w5dxp.com

Loading Coils; was : Vincent antenna
 

Gene Fuller wrote:
Try some extreme numbers and you can see that the expected results do
not occur.

A 10TPI, 2" dia., 100T coil used on 4 MHz is NOT an extreme
example. Why don't you just admit that you and W8JI have been
wrong for years and get it over with?
--
73, Cecil http://www.w5dxp.com

Loading Coils; was : Vincent antenna
 

Cecil Moore wrote:
Owen Duffy wrote:
It seems reasonable that a stand alone coil can be characterised as a
transmission line having a delay that equates to an electrical length
in degrees, radians, wavelengths or a velocity factor. In fact the
inductance calculator at http://hamwaves.com/antennas/inductance.html
is based on that approach and shows the calculated value of Beta.

But, but, but, Owen, the first reference in that web page
is the very Corum IEEE paper that I referenced that has
been completely and totally debunked by most of the gurus
on this newsgroup.

Cecil,

I don't believe anyone has actually challenged what Corum *says*. What
*has* been challenged is your misreading of the paper, especially the
required conditions for the validity of the analysis.

73,
Gene
W4SZ

Loading Coils; was : Vincent antenna
 

Cecil Moore wrote:
Gene Fuller wrote:
Try some extreme numbers and you can see that the expected results do
not occur.

A 10TPI, 2" dia., 100T coil used on 4 MHz is NOT an extreme
example. Why don't you just admit that you and W8JI have been
wrong for years and get it over with?

I never said that condition was extreme. Try the calculator at 40 kHz
and see what you get.

73,
W4SZ
Gene

Loading Coils; was : Vincent antenna
 

Cecil Moore wrote:
Gene Fuller wrote:
And for the 21st time, we are talking about delay, not phase shift.
That point seems difficult for you to fathom.

They are related in a traveling-wave environment. They are
virtually unrelated in a standing-wave environment. W8JI
asserts that the delay through a 100T coil at 4 MHz is
3 ns which is impossible. If he had asserted that the
standing-wave current undergoes a 4.5 degree phase shift
through that coil, we wouldn't be having this argument
because the phase of standing-wave current is virtually
constant over the length of a 1/2WL dipole. At the ends
of a dipole longer than 1/2WL, it does an abrupt 180 degree
phase shift. W8JI and W7EL seem to be totally ignorant of
that fact of physics since they both tried to use standing-
wave current to "measure" phase-shift/delay.

Cecil,

As usual you clipped out the interesting part of the message.

By the way, saying something is "impossible" is religion, not science.
The distance from one end of the coil to the other is clearly within
reach without violating the speed of light.

73,
Gene
W4SZ

Loading Coils; was : Vincent antenna
 

Gene Fuller wrote:
Cecil Moore wrote:
Gene Fuller wrote:
Try some extreme numbers and you can see that the expected results do
not occur.

A 10TPI, 2" dia., 100T coil used on 4 MHz is NOT an extreme
example. Why don't you just admit that you and W8JI have been
wrong for years and get it over with?

I never said that condition was extreme. Try the calculator at 40 kHz
and see what you get.

73,
W4SZ
Gene

Where did the calculator gets its' method/formula/equation(s) from, W8JI
:-o

Regards,
JS