Tom Donaly wrote:
The same thing can be accomplished, above, using an open stub and
measuring the voltage at both ends. All this is just theoretical,
though, because line loss will skew the results. Besides, why try to
measure current or voltage when all you have to do is measure length
and frequency?

Tom, you are not going to understand what I am saying until
you perform the stub exercise I provided. Just do one at a
time. Assume ideal lossless conditions with VF=1.0.

---600 ohm line---+---10 deg 100 ohm line---open

How many degrees of 600 ohm line does it take to make the
above stub look like 1/4 wavelength, i.e. 90 degrees?

Until you perform the exercise, you are just creating
diversions and avoiding the technical truth.
--
73, Cecil http://www.w5dxp.com

Keith Dysart wrote:
On Dec 4, 11:13 pm, Cecil Moore wrote:
Tom Donaly wrote:
50 ohm Shorted line 8.5655 meters long. Frequency = 7 Mhz. 2 volt 50 ohm
generator. Current at input = 12.361 milliamps. Current at short =
40 milliamps. Divide the current at the imput of the line by the current
at the short and take the arc sine (in radian mode) of the result. This
is 1.2566. Now take Beta = .14671 and multiply it by the length 8.5655.
This also equals 1.2566, which is the angular length of the shorted
line. Will someone explain how this works to Cecil?
You won't understand what I am talking about until you perform
the stub experiments that I previously posted.

---600 ohm line---+---10 deg, 100 ohm line---open-circuit

How many degrees of 600 ohm line does it take to resonate
that stub to an electrical 1/4WL?

--5 deg, 100 ohm line--+--600 ohm line--+--5 deg, 100 ohm line--open

How many degrees of 600 ohm line does it take to resonate
that stub to an electrical 1/4WL?

You have said multiple times that the electrical length of a
quarter wave stub must be 90 electrical degress, so the
computation is too easy...

1) x + 10 = 90
x = 80 degrees for the 600 Ohm line
2) 5 + x + 5 = 90
x = 80 degrees for the 600 Ohm line

although I suspect others will disagree with your solution.

I have not yet provided a solution. Your's is *wrong*.

The 90 degree physical solution is *wrong* because it results
in more than 90 electrical degrees. Please try again.
--
73, Cecil http://www.w5dxp.com

On Dec 5, 9:14 am, Cecil Moore wrote:
Keith Dysart wrote:
On Dec 4, 11:13 pm, Cecil Moore wrote:
You won't understand what I am talking about until you perform
the stub experiments that I previously posted.

---600 ohm line---+---10 deg, 100 ohm line---open-circuit

How many degrees of 600 ohm line does it take to resonate
that stub to an electrical 1/4WL?

--5 deg, 100 ohm line--+--600 ohm line--+--5 deg, 100 ohm line--open

How many degrees of 600 ohm line does it take to resonate
that stub to an electrical 1/4WL?

You have said multiple times that the electrical length of a
quarter wave stub must be 90 electrical degress, so the
computation is too easy...

1) x + 10 = 90
x = 80 degrees for the 600 Ohm line
2) 5 + x + 5 = 90
x = 80 degrees for the 600 Ohm line

although I suspect others will disagree with your solution.

I have not yet provided a solution. Your's is *wrong*.

The 90 degree physical solution is *wrong* because it results
in more than 90 electrical degrees. Please try again.

I thought that when you specified 5 and 10 degrees in your
problem statement, you meant electrical degrees. That is, the
phase shift encountered by the forward travelling wave.

Certainly, the answer was in terms of electrical degrees. That is,
the phase shift encountered by the forward travelling wave.

Or have I misunderstood the meaning of 'electrical degrees'?

Or perhaps 'electrical degrees' do not sum either?

Keith Dysart wrote:
I thought that when you specified 5 and 10 degrees in your
problem statement, you meant electrical degrees. That is, the
phase shift encountered by the forward travelling wave.

That specification is the same for physical and electrical
degrees because we are dealing with a single Z0 piece of
transmission line. The 100 ohm line is indeed 10 degrees
long both physically and electrically.

Certainly, the answer was in terms of electrical degrees. That is,
the phase shift encountered by the forward travelling wave.

You, and others, are going to be surprised to find out the
600 ohm section is only 43 degrees of physical length. How
can 43 degrees of 600 ohm line add to 10 degrees of 100 ohm
line to equal 90 electrical degrees of stub? Hint: Like I
told Roy and Tom years ago, there's a 37 degree phase shift
at the impedance discontinuity between the 600 ohm line and
the 100 ohm line. 43+37+10 = 90 electrical degrees.

Understand that simple stub example and you will understand
loaded mobile antennas. Most of the "experts" here are just
full of you-know-what.
--
73, Cecil http://www.w5dxp.com

On Dec 5, 10:01 am, Cecil Moore wrote:
Keith Dysart wrote:
I thought that when you specified 5 and 10 degrees in your
problem statement, you meant electrical degrees. That is, the
phase shift encountered by the forward travelling wave.

That specification is the same for physical and electrical
degrees because we are dealing with a single Z0 piece of
transmission line. The 100 ohm line is indeed 10 degrees
long both physically and electrically.

Certainly, the answer was in terms of electrical degrees. That is,
the phase shift encountered by the forward travelling wave.

You, and others, are going to be surprised to find out the
600 ohm section is only 43 degrees of physical length.

Hardly surprised. After all, the same can be achieved with an
inductor and/or capacitor which has essentially
0 physical (or electrical) length.

How
can 43 degrees of 600 ohm line add to 10 degrees of 100 ohm
line to equal 90 electrical degrees of stub? Hint: Like I
told Roy and Tom years ago, there's a 37 degree phase shift
at the impedance discontinuity between the 600 ohm line and
the 100 ohm line. 43+37+10 = 90 electrical degrees.

So the important take-away is that the system phase shift is
NOT equal to the sum of the phase shifts of the components.

This then begs the question, is the physical (or electrical) phase
shift in the components of much interest?

Keith Dysart wrote:
Hardly surprised. After all, the same can be achieved with an
inductor and/or capacitor which has essentially
0 physical (or electrical) length.

Only true for a lumped inductor which doesn't exist
in reality. Any large coil, such as the coil tested
by W8JI, has considerable electrical length at 4 MHz.
This electrical length is what some folks have been
denying for years even though they should certainly
know better by now.

This then begs the question, is the physical (or electrical) phase
shift in the components of much interest?

It is - when someone tries to convince the world that
there is a 3 ns delay through a 2" dia, 10 TPI,
100 turn coil. The electrical length (phase shift)
through a coil is necessary and sufficient to kill
the old wives tales being supported by some so-called
"experts" on this newsgroup.
--
73, Cecil http://www.w5dxp.com

On Dec 5, 10:40 am, Cecil Moore wrote:
Keith Dysart wrote:
Hardly surprised. After all, the same can be achieved with an
inductor and/or capacitor which has essentially
0 physical (or electrical) length.

Only true for a lumped inductor which doesn't exist
in reality. Any large coil, such as the coil tested
by W8JI, has considerable electrical length at 4 MHz.
This electrical length is what some folks have been
denying for years even though they should certainly
know better by now.

This then begs the question, is the physical (or electrical) phase
shift in the components of much interest?

It is - when someone tries to convince the world that
there is a 3 ns delay through a 2" dia, 10 TPI,
100 turn coil. The electrical length (phase shift)
through a coil is necessary and sufficient to kill
the old wives tales being supported by some so-called
"experts" on this newsgroup.

But again, given that the key message is "that the system phase shift
is NOT equal to the sum of the phase shifts of the components.",
why is the question of delay through the coil important?

Is it just to have a "debate" with some called experts?

Or does it offer some advancement in the solution of antenna
problems? Having computed (or measured) the delay through
the coil, how would this alter the design of the antenna?

....Keith

"Keith Dysart" wrote in message
...
On Dec 5, 10:40 am, Cecil Moore wrote:
Keith Dysart wrote:
Hardly surprised. After all, the same can be achieved with an
inductor and/or capacitor which has essentially
0 physical (or electrical) length.

Only true for a lumped inductor which doesn't exist
in reality. Any large coil, such as the coil tested
by W8JI, has considerable electrical length at 4 MHz.
This electrical length is what some folks have been
denying for years even though they should certainly
know better by now.

This then begs the question, is the physical (or electrical) phase
shift in the components of much interest?

It is - when someone tries to convince the world that
there is a 3 ns delay through a 2" dia, 10 TPI,
100 turn coil. The electrical length (phase shift)
through a coil is necessary and sufficient to kill
the old wives tales being supported by some so-called
"experts" on this newsgroup.

But again, given that the key message is "that the system phase shift
is NOT equal to the sum of the phase shifts of the components.",
why is the question of delay through the coil important?

Is it just to have a "debate" with some called experts?

Or does it offer some advancement in the solution of antenna
problems? Having computed (or measured) the delay through
the coil, how would this alter the design of the antenna?

...Keith


That train of arguments and nitpicking developed from the main argument
about distribution of (standing wave) current along the loading coil and
antenna.
"Gurus" and some literature claimed that current is the SAME at both end of
the coil (Kirchoff "said so"). That would mean that current remains constant
along the coil and then drops drastically towards (almost) zero at the tip.
This makes loaded whip antenna look better than it is.

The reality is that current drops around 40 - 60 % along the loading coil,
which makes the distribution along the remaining stinger starting with less
and overall efficiency less.

The key to understand the loaded radiator is to trying to maximize the
current in the physical "straight wire" - so the higher the coil, larger
hat, will stretch the high current portion of the radiator and make it more
efficient. Fooling yourself by modeling the loading coil as a lumped
inductance and making it look better in modeling program does not help.
Again, this effect is magnified in multi element loaded arrays, so while
some might consider this not a big deal in a mobile whip, the errors would
magnify in multielement designs.

I hope I can get the main "problem" across, the rest was digging into the
smaller effects like coil radiates, junction impedance discontinuity, bla,
bla....

Now I also understand the small "bump" increase in the current at the bottom
of the coil due to some loses that reflected wave encounter on the way
"there and back" to the tip of the radiator from the bottom of the coil (?)

73 Yuri, www.K3BU.us

Cecil Moore wrote:
Keith Dysart wrote:
Hardly surprised. After all, the same can be achieved with an
inductor and/or capacitor which has essentially
0 physical (or electrical) length.

Only true for a lumped inductor which doesn't exist
in reality. Any large coil, such as the coil tested
by W8JI, has considerable electrical length at 4 MHz.
This electrical length is what some folks have been
denying for years even though they should certainly
know better by now.

This then begs the question, is the physical (or electrical) phase
shift in the components of much interest?

It is - when someone tries to convince the world that
there is a 3 ns delay through a 2" dia, 10 TPI,
100 turn coil. The electrical length (phase shift)
through a coil is necessary and sufficient to kill
the old wives tales being supported by some so-called
"experts" on this newsgroup.

Cecil,

No one has ever said that there is a 3 ns delay *through* the coil. Ask
Richard Harrison if Faraday screens work, even without any conduction
path at all. Radiation is real.

You keep trying to change the topic, but the only debate is the relative
contributions of "round and round the wire" vs. other coupling. The math
is not easy, and the problem is not readily amenable to solution by
intuition and word games.

73,
Gene
W4SZ

On Wed, 5 Dec 2007 07:18:47 -0800 (PST), Keith Dysart
wrote:

This then begs the question, is the physical (or electrical) phase
shift in the components of much interest?

Hi Keith,

Its consideration is listed by the Department of Commerce as an
important occupation for the home bound and invalid during the Winter
months.

73's
Richard Clark, KB7QHC