Loading Coils; was : Vincent antenna
 

Richard Clark wrote:
On Wed, 05 Dec 2007 15:43:11 GMT, Cecil Moore
wrote:

Toroidal current pickup coils designed by W7EL
with the standard voltage probes.

What did you load those pickup coils with?
Do you have an URL to the design?

It was in an article by Roy, W7EL, but I can't
lay my hands on it at the moment.
--
73, Cecil http://www.w5dxp.com

Loading Coils; was : Vincent antenna
 

Roy Lewallen wrote:
EZNEC does not, either
in internal calculations or in reporting, split the current into any
kind of "traveling wave", "standing wave", or any other kind of wave
components.

Sorry, you are wrong, Roy. EZNEC faithfully reports
traveling wave current when reflected wave current
is not present. If you had looked at the file I
sent to you instead of threatening to refund my
money, you would know that.

Model a rhombic antenna. EZNEC reports the traveling
wave amplitude and phase.

Model a lossless stub. EZNEC reports the standing
wave amplitude and phase.
--
73, Cecil http://www.w5dxp.com

Loading Coils; was : Vincent antenna
 

On 5 Dec, 19:26, (Richard Harrison) wrote:
Art wrote:

"These are not my laws, they are Maxwell`s"
Yes. They are old butthey still work. Art`s discovery of Gaus has not
replaced Maxwell`s equations.

The origin of Maxwell`s equations may be of interest.

Faraday found that voltage induced in a loop is directly proportional to
the rate of change of the magnetic flux which passes through a loop.
Voltage arises more or less all along the contour of the loop.

Faraday`s law is: V = -dphi/dt

Flux passing through the contour is the integral of the flux density.

The rate of change of the total flux is thus the tate of change of the
integral.

In the years 1856-1873, Maxwell rewrote Faraday`s law by substiturions
to equate the electric field with the changing magnetic flux. The
contour of the magnetic field does not require a current carrying wire
around it.

An electric field is present in space so long as a changing magnetic
field is present.

Another discovery was that the magnetomotive force around a current is 4
pi I. It does not depend on shape or distance in the contour.

Displacement flux is created in a dielectric whenever an electric field
is applied. Electric charges can create it, so it is expressed in
coulombs per square meter. Displacement current is proportional to the
rate of change of the dielectric displacement.

Maxwell knew about displacement current and speculated it would poduce
magnetic flux the same as conduction current does. That was the key to
electromagnetic radiation. If an alternating current flows in a wire, an
alternating magnetic field will be produced in the space around the
wire. The alternating magnetic field creates an alternating electric
field in the surrounding space. This alternating electric field creates
an alternating displacement "current" in the dielectric (maybe it should
be called a displacement stress since the dielectric is an insulator) of
space which gives rise to another alternating magnetic field. This
expanding succession of fields continues ad infinitum. Heinrich Hertz
proved in 1888 that Mexwell`s speculations were correct.

The preceding is presented much more elegantly by B. Whitfield Griffith,
Jr. in "Radio-Electronic Transmission Fundamentals" from which it was
lifted.

Now you are being silly Richard.Try reading what the discussion is
about
before you pick up a book to quote. Maxwells laws are NOT in
contention.
I have no idea where you got that from, maybe another thread.
What we are talking about is the trail from Newton to Maxwellian laws
which will allow for a full understanding. We have the laws which
we all can agree on but the present trail has a lot of gaps.
Why do you think that Einstein and many others spent so much time
trying to fill in the gaps especially with respect to particles?
Or was it in a book that was held from distribution?
Richard hold off for 24 hours before you post, you mind is not
as agile as it once was.
Art

Loading Coils; was : Vincent antenna
 

AI4QJ wrote:
Going further, I am
still trying to consider how the extra angle can also be absorbed "into" an
impedance discontinuity.

I have started a phasor diagram of it but it is not
finished yet. Maybe a Smith Chart explanation will
work. All lines are lossless.

On a Smith Chart normalized to 100 ohms, lay out the
10 degrees of 100 ohm line from the infinity point,
i.e. the open-circuit point. The reactance value
is tan(90-10) = 5.67. That means the reactance value
is 5.67*100 = -j567 ohms which has to be the value
at the impedance discontinuity.

Now on a Smith Chart normalized to 600 ohms, lay out
the x degrees of 600 ohm line from the zero point
to the point where -j567/600 is located. Read the
number of degrees required. It is Arctan(567/600)
which is equal to ~43 degrees.

The phase shift at the impedance discontinuity is
therefore 90-10-43 = 37 degrees.
--
73, Cecil http://www.w5dxp.com

Loading Coils; was : Vincent antenna
 

On Wed, 5 Dec 2007 16:21:39 -0800 (PST), art
wrote:

On 5 Dec, 12:35, Richard Clark wrote:
On Wed, 5 Dec 2007 12:18:17 -0800 (PST), art
wrote:

do not stray from the term "RESULTANT VECTOR"

It might help to know the vector units;
it might help to know result of what vector operation.

73's
Richard Clark, KB7QHC

Richard,
You are obviously behind in physics with this succession of questions
like a prosecutor adressing the accused.
You start off with a vector along the axis

What is the vector's unit?

73's
Richard Clark, KB7QHC

Loading Coils; was : Vincent antenna
 

On Wed, 05 Dec 2007 22:02:50 -0600, Cecil Moore
wrote:

Richard Clark wrote:
On Wed, 05 Dec 2007 15:43:11 GMT, Cecil Moore
wrote:

Toroidal current pickup coils designed by W7EL
with the standard voltage probes.

What did you load those pickup coils with?
Do you have an URL to the design?

It was in an article by Roy, W7EL, but I can't
lay my hands on it at the moment.
What did you load those pickup coils with?

Loading Coils; was : Vincent antenna
 

On Wed, 05 Dec 2007 15:43:11 GMT, Cecil Moore
wrote:

Richard Clark wrote:
Using what probes?

Toroidal current pickup coils designed by W7EL
with the standard voltage probes.
What voltages did they present to the O'scope?

Loading Coils; was : Vincent antenna
 

Cecil Moore wrote:
AI4QJ wrote:
Going further, I am still trying to consider how the extra angle can
also be absorbed "into" an impedance discontinuity.

I have started a phasor diagram of it but it is not
finished yet. Maybe a Smith Chart explanation will
work. All lines are lossless.

On a Smith Chart normalized to 100 ohms, lay out the
10 degrees of 100 ohm line from the infinity point,
i.e. the open-circuit point. The reactance value
is tan(90-10) = 5.67. That means the reactance value
is 5.67*100 = -j567 ohms which has to be the value
at the impedance discontinuity.

Now on a Smith Chart normalized to 600 ohms, lay out
the x degrees of 600 ohm line from the zero point
to the point where -j567/600 is located. Read the
number of degrees required. It is Arctan(567/600)
which is equal to ~43 degrees.

The phase shift at the impedance discontinuity is
therefore 90-10-43 = 37 degrees.

Wrong. In the first place, you obviously don't know the criterion for
resonance. In the second place you just assume the number
90 without any reason. In the third place, the number 37
has only your assumption for the necessity of a 90 degree
phase shift to justify its existence. As I wrote before, this
is pretty poor shooting for a professional symbol slinger.
73,
Tom Donaly, KA6RUH

Loading Coils; was : Vincent antenna
 

Richard Clark wrote:
What did you load those pickup coils with?

Sorry, I don't remember. I just copied what
W7EL suggested. It may have been a 50 ohm
carbon resistor at the end of a length of
50 ohm coax.
--
73, Cecil http://www.w5dxp.com

Loading Coils; was : Vincent antenna
 

On Dec 5, 8:47 pm, "AI4QJ" wrote:
And I was making a big mistake considering it as a lumped component (like
the 1950's concept) until I was brought up to date here so I should not
badmouth ARRL. That photo using a thermocouple type ammeter on both ends of
the coil, where they even turned the coil upside down and repeated the
measurement was pretty convincing although there is enough controversy by
the people in this ng that it needs to be verified more. Going further, I am
still trying to consider how the extra angle can also be absorbed "into" an
impedance discontinuity. You are saying that 44 degrees phase shift is equal
to 44 degrees electrical length? Thus, using "phase shift", provided
(resistance free) by nature, it is possible to have electrical length over
zero physical length? I still have some considering to do on that one but it
is immensly interesting to say the least.

In your deliberations, do consider the case where the impedance
matching is obtained using lumped components. All of the "phase
shift" will then be occurring over 0 length.

I am reminded of the small joke:
Three people need to rent a room for the night. The each give the
clerk
$10 for a total of $30. The clerk realizes the price is $25 and gives
the
valet 5 one dollar bills to refund to the people. But it is hard to
split
$5 three ways, so they each take $1 and tip the valet $2.
So 3 people each paid $9 and the valet got $2 for a total of $29.
But the original was $30. Where did the extra $1 go?

Perhaps there is just no reason why the "phase shifts" should add
to 90. That would make the problem go away.

....Keith