Keith Dysart wrote:
On Dec 6, 9:48 pm, Cecil Moore wrote:
So are we agreed that a 43.4 degree stub terminated in
0-j567 ohms impedance is electrically 1/4WL, i.e. 90
degrees long?

There are many ways to get the 0 input impedance:
(1)- 43.4 degrees of 600 ohm line terminated in a lumped 0-j567 impedance
(assuming I recall the problem corrrectly and you did the math
correctly)
(2)- 43.4 degrees of 600 ohm line followed by 46.6 degrees of 600 ohm
line, open at the end
(3)- 43.4 degrees of 600 ohm line followed by 10 degrees (IIRC) of 100
ohm line, open at the end
(4)- a short
(5)- 180 degrees of any impedance line shorted at the end
- and many, many more

If you calculate the complex rho and calculate the phase
shift provided by a -j567 impedance, you will agree with
my statement above.

Are you claiming that all of these are electrically 1/4WL ?

Of course not!!!! I numbered your examples above. Examples
1-3 are electrically 1/4WL long. Example 4 is 0 WL long.
Example 5 is 1/2WL long.

All my remarks apply only to stubs and antennas that are
electrically 1/4WL long. My remarks do NOT apply to any
stub or antenna that is not electrically 1/4WL long. An
ideal open stub that is 3/4WL long has the same impedance
as a 1/4WL stub but is it obviously not 1/4WL long.
--
73, Cecil http://www.w5dxp.com

On Dec 7, 12:37 pm, Cecil Moore wrote:
Keith Dysart wrote:
On Dec 6, 9:48 pm, Cecil Moore wrote:
So are we agreed that a 43.4 degree stub terminated in
0-j567 ohms impedance is electrically 1/4WL, i.e. 90
degrees long?

There are many ways to get the 0 input impedance:
(1)- 43.4 degrees of 600 ohm line terminated in a lumped 0-j567 impedance
(assuming I recall the problem corrrectly and you did the math
correctly)
(2)- 43.4 degrees of 600 ohm line followed by 46.6 degrees of 600 ohm
line, open at the end
(3)- 43.4 degrees of 600 ohm line followed by 10 degrees (IIRC) of 100
ohm line, open at the end
(4)- a short
(5)- 180 degrees of any impedance line shorted at the end
- and many, many more

If you calculate the complex rho and calculate the phase
shift provided by a -j567 impedance, you will agree with
my statement above.

Are you claiming that all of these are electrically 1/4WL ?

Of course not!!!! I numbered your examples above. Examples
1-3 are electrically 1/4WL long. Example 4 is 0 WL long.
Example 5 is 1/2WL long.

All my remarks apply only to stubs and antennas that are
electrically 1/4WL long. My remarks do NOT apply to any
stub or antenna that is not electrically 1/4WL long. An
ideal open stub that is 3/4WL long has the same impedance
as a 1/4WL stub but is it obviously not 1/4WL long.

Your original claim was that 43.4 degrees of 600 ohm
line terminated with 0-j567 was electricall 90 degrees long.
You made no reference to how the 0-j567 was obtained.

You have said that 1, 2 and 3 from above are electically
90 degrees.

How about:
(6) 43.4 degrees of 600 ohm line, 180 degrees of arbitrary
line terminated in a lump of 0-j567. This is just another
way of placing 0-j567 at the end of the 43.4 degrees of
600 ohm line.

And (5), if we use 600 ohm line is also 43.4 degrees of
600 ohm line terminated with 0-j567, this being obtained
with 136.6 degrees of 600 ohm line that is short
circuited.

So while I can accept your statement , "My remarks do
NOT apply to any stub or antenna that is not electrically
1/4WL long.", I am having great difficulty coming up for
a rule so that I will know when your remarks apply.

Can you provide a rule for discerning when a stub or
antenna is electrically 1/4WL long?

....Keith

Keith Dysart wrote:
You have said that 1, 2 and 3 from above are electically
90 degrees.

How about:
(6) 43.4 degrees of 600 ohm line, 180 degrees of arbitrary
line terminated in a lump of 0-j567. This is just another
way of placing 0-j567 at the end of the 43.4 degrees of
600 ohm line.

Of course, if you add 180 degrees you have added 180
degrees to whatever existed before. Do you disagree?

Can you provide a rule for discerning when a stub or
antenna is electrically 1/4WL long?

Of course! When the reflected wave undergoes a phase
shift of 180 degrees in its round trip to the end of
the stub and back, the stub is electrically 1/4WL long.
How can you disagree with that?
--
73, Cecil http://www.w5dxp.com

On Dec 7, 4:21 pm, Cecil Moore wrote:
Keith Dysart wrote:
You have said that 1, 2 and 3 from above are electically
90 degrees.

How about:
(6) 43.4 degrees of 600 ohm line, 180 degrees of arbitrary
line terminated in a lump of 0-j567. This is just another
way of placing 0-j567 at the end of the 43.4 degrees of
600 ohm line.

Of course, if you add 180 degrees you have added 180
degrees to whatever existed before. Do you disagree?

So this meets the criteria you originally proposed and
is an example of 90 degree electical length?

Can you provide a rule for discerning when a stub or
antenna is electrically 1/4WL long?

Of course! When the reflected wave undergoes a phase
shift of 180 degrees in its round trip to the end of
the stub and back, the stub is electrically 1/4WL long.
How can you disagree with that?

So (4), a short, meets this criteria. It did not have to go
far down the stub, but it did arrive back with a 180 degree
phase change. But previously, you did not include (4).

Is it now in the list?

....Keith

Keith Dysart wrote:
Cecil Moore wrote:
Keith Dysart wrote:
Of course, if you add 180 degrees you have added 180
degrees to whatever existed before. Do you disagree?

So this meets the criteria you originally proposed and
is an example of 90 degree electical length?

Don't be silly. 180 degrees plus any positive angle
is more than 180 degrees.

The context was mobile loaded antennas shorter than
a physical 1/4WL.
--
73, Cecil http://www.w5dxp.com

On Dec 8, 12:43 am, Cecil Moore wrote:
Keith Dysart wrote:
Cecil Moore wrote:
Keith Dysart wrote:
Of course, if you add 180 degrees you have added 180
degrees to whatever existed before. Do you disagree?

So this meets the criteria you originally proposed and
is an example of 90 degree electical length?

Don't be silly. 180 degrees plus any positive angle
is more than 180 degrees.

The context was mobile loaded antennas shorter than
a physical 1/4WL.

Hmmmm. So you are no longer in agreement with your
original question:
"So are we agreed that a 43.4 degree stub terminated
in 0-j567 ohms impedance is electrically 1/4WL, i.e.
90 degrees long?"

This is good. You can now understand why some were
not quick to jump to agreement.

The concept of electrical/physical degrees is an
occasionally useful way to think about delay on
a transmission line that is used in a single frequency
environment. It even helps understand stubs where
the reflection arrives back with some phase shift
from the original. But extending the concept to lumped
circuits or expecting to find 90 degrees when different
impedances are involved has little value. It leads
to worthless questions like "where did the missing
degrees go?"

This is much like ascribing excessive reality to
"reflected power" which leads to worthless questions
like "where did the reflected power go?".

Or asking "where is the missing dollar?'. The flawed
underpinnings lead to worthless questions. Well maybe
not worthless, like the hotel puzzle, they test the
ability of the answerer to detect flawed assumptions.

....Keith

Keith Dysart wrote:
On Dec 8, 12:43 am, Cecil Moore wrote:
Keith Dysart wrote:
Cecil Moore wrote:
Keith Dysart wrote:
Of course, if you add 180 degrees you have added 180
degrees to whatever existed before. Do you disagree?
So this meets the criteria you originally proposed and
is an example of 90 degree electical length?
Don't be silly. 180 degrees plus any positive angle
is more than 180 degrees.

The context was mobile loaded antennas shorter than
a physical 1/4WL.

Hmmmm. So you are no longer in agreement with your
original question:
"So are we agreed that a 43.4 degree stub terminated
in 0-j567 ohms impedance is electrically 1/4WL, i.e.
90 degrees long?"

Now I understand your confusion. I was talking about
a -j567 ohm *capacitor*, not a virtual impedance.

I was, of course, using the "impedor" definition of
impedance but since that confused you, let me restate
the question:

"So are we agree that a 43.4 degree stub terminated in
a -j567 ohm impedor is electrically 1/4WL, i.e. 90
degrees long?"

This was the original meaning of the question. I'm sorry
that you took it the wrong way and wasted so many postings
on such a trivial misunderstanding.

It leads
to worthless questions like "where did the missing
degrees go?"

Click on "Load Dat" in the EZNEC model below. There are
*no* missing degrees. All necessary degrees are present
and accounted for. But you will never see them if you
are trying to use standing-wave current to see them.

http://www.w5dxp.com/coil512.ez

This is much like ascribing excessive reality to
"reflected power" which leads to worthless questions
like "where did the reflected power go?".

Since energy must be conserved, the proper question
is: "Where did the reflected wave *energy* go?" Do
you even know the answer? The answer is that there
is exactly the amount of energy existing in a transmission
line to support the forward wave and the reflected wave.
--
73, Cecil http://www.w5dxp.com

On Dec 8, 9:18 am, Cecil Moore wrote:
Keith Dysart wrote:
On Dec 8, 12:43 am, Cecil Moore wrote:
Keith Dysart wrote:
Cecil Moore wrote:
Keith Dysart wrote:
Of course, if you add 180 degrees you have added 180
degrees to whatever existed before. Do you disagree?
So this meets the criteria you originally proposed and
is an example of 90 degree electical length?
Don't be silly. 180 degrees plus any positive angle
is more than 180 degrees.

The context was mobile loaded antennas shorter than
a physical 1/4WL.

Hmmmm. So you are no longer in agreement with your
original question:
"So are we agreed that a 43.4 degree stub terminated
in 0-j567 ohms impedance is electrically 1/4WL, i.e.
90 degrees long?"

Now I understand your confusion. I was talking about
a -j567 ohm *capacitor*, not a virtual impedance.

I was, of course, using the "impedor" definition of
impedance but since that confused you, let me restate
the question:

"So are we agree that a 43.4 degree stub terminated in
a -j567 ohm impedor is electrically 1/4WL, i.e. 90
degrees long?"

This was the original meaning of the question. I'm sorry
that you took it the wrong way and wasted so many postings
on such a trivial misunderstanding.

So does this new question rule out the cases (previously
accepted) where the 0-j567 is obtained with 46.4 degrees
of 600 ohm line or 10 degrees of 100 ohm line? These are
not lumped capacitors.

Some consistency that persists longer than one post would
be valuable.

....Keith

Keith Dysart wrote:
So does this new question rule out the cases (previously
accepted) where the 0-j567 is obtained with 46.4 degrees
of 600 ohm line or 10 degrees of 100 ohm line? These are
not lumped capacitors.

No, but they are an electrical 1/4WL, not any
other length. The electrical length of a stub
is whatever it is. If it is not 1/4WL, it is
some other length. Why is that difficult to
understand?
--
73, Cecil http://www.w5dxp.com

On Dec 8, 5:59 pm, Cecil Moore wrote:
Keith Dysart wrote:
So does this new question rule out the cases (previously
accepted) where the 0-j567 is obtained with 46.4 degrees
of 600 ohm line or 10 degrees of 100 ohm line? These are
not lumped capacitors.

No, but they are an electrical 1/4WL, not any
other length. The electrical length of a stub
is whatever it is. If it is not 1/4WL, it is
some other length. Why is that difficult to
understand?

Well, I know what I mean by 1/4WL and in my
definition there is no way that (46.4 + 10) = 90.

However I am trying to help you articulate your
definition in a way that is sufficiently precise
that I can use it to determine what you would
consider to be 1/4WL. Unfortunately, at the
moment, it is sufficiently fuzzy that the only
way to determine if something is 90 degrees
(according to your definition) is to ask you.
The need of an oracle to answer such questions
is not the basis for sound science.

Tautologies such as "If it is not 1/4WL, it is
some other length." do not further the definition,
but are good if you want to keep the job of
oracle.

....Keith