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

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

Of course, those are *physical* degrees. We are
talking about *electrical* degrees. It is impossible
to get the reflected wave in phase with the forward
wave unless there is an electrical 90 degree phase
shift.

If you lay the 43.4 degrees out starting at Z=0
toward the load on the Smith Chart and lay the
10 degrees out starting at Z=infinity toward the
source, you will observe the phase shift caused
by the impedance discontinuity.

... the only
way to determine if something is 90 degrees
(according to your definition) is to ask you.

All one has to do is plot it on a Smith Chart
and the number of electrical degrees is obvious.
If you don't know how to use a Smith Chart it
might be time to learn how.
--
73, Cecil http://www.w5dxp.com