Standing Wave Phase
 

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?
73,
Tom Donaly, KA6RUH

Standing Wave Phase
 

Tom, KA6RUH wrote:
"Will somebody explain how this works to Cecil?"

Cecil is capable of solving practically any transmission line problem
without help from anyone. Tom could have been more descriptive by saying
if his line were 50-ohm coax with a velocity factor of about 2/3.

Best regards, Richard Harrison, KB5WZI

Standing Wave Phase
 

On Dec 4, 9:06 pm, "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)

arc cosine, perhaps?

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?

Cecil either knows this, in which case it is unnecessary to explain
it,
or he does not, in which case it will be impossible.

....Keith

Standing Wave Phase
 

Richard Harrison wrote:
Tom, KA6RUH wrote:
"Will somebody explain how this works to Cecil?"

Cecil is capable of solving practically any transmission line problem
without help from anyone. Tom could have been more descriptive by saying
if his line were 50-ohm coax with a velocity factor of about 2/3.

Best regards, Richard Harrison, KB5WZI


No he isn't, Richard, or he wouldn't have made the ignorant statement
that there is no phase information in a standing wave. As to the
velocity factor, the line is one of Cecil's ideal, lossless lines. The
velocity factor is 1. Nice try.
73,
Tom Donaly, KA6RUH

Standing Wave Phase
 

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?
--
73, Cecil http://www.w5dxp.com

Standing Wave Phase
 

Richard Harrison wrote:
Tom, KA6RUH wrote:
"Will somebody explain how this works to Cecil?"

Cecil is capable of solving practically any transmission line problem
without help from anyone. Tom could have been more descriptive by saying
if his line were 50-ohm coax with a velocity factor of about 2/3.

Tom apparently doesn't realize that he needs to be dealing
with more than one Z0 to observe the difference between
electrical degrees and physical degrees. I invite everyone
to solve the dual-Z0 stub problem that I earlier presented
and repeated tonight.
--
73, Cecil http://www.w5dxp.com

Standing Wave Phase
 

Tom Donaly wrote:
No he isn't, Richard, or he wouldn't have made the ignorant statement
that there is no phase information in a standing wave.

Please get it right, Tom. I said there is no phase
information in the standing-wave phase. The phase
information is certainly there but it is in the
amplitude, not in the phase. The following graph
proves it:

http://www.w5dxp.com/travstnd.gif

The phase of the standing-wave is absolutely flat.
--
73, Cecil http://www.w5dxp.com

Standing Wave Phase
 

Keith Dysart wrote:
On Dec 4, 9:06 pm, "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)

arc cosine, perhaps?

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?

Cecil either knows this, in which case it is unnecessary to explain
it,
or he does not, in which case it will be impossible.

...Keith
Right. I lied.
73,
Tom Donaly, KA6RUH

Standing Wave Phase
 

Tom Donaly wrote:
Keith Dysart wrote:
On Dec 4, 9:06 pm, "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)

arc cosine, perhaps?

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?

Cecil either knows this, in which case it is unnecessary to explain
it,
or he does not, in which case it will be impossible.

...Keith
Right. I lied.
73,
Tom Donaly, KA6RUH
To amplify:
Arc Cosine is correct. And the comment on Cecil is right on the mark.
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?
73,
Tom Donaly, KA6RUH

Standing Wave Phase
 

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?
--
73, Cecil http://www.w5dxp.com

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.