rickman wrote:
On 7/9/2015 1:58 PM, wrote:
rickman wrote:
On 7/9/2015 9:14 AM, Ralph Mowery wrote:
"Jeff" wrote in message
...

The SWR has to be the same at any point on the coax or transmission line
minus the loss in the line. A simple swr meter may show some differance
because of the way that kind of meter works. By changing the length of
the
line , the apparent SWR may be differant at that point.

There is no such thing as apparent SWR. It is what it is in a given
place.


By 'apparent SWR' he means as indicated SWR on the meter, and yes it can
change at various point on the line due to inadequacies in the meter; the
'real' VSWR will of course remain the same at any point on a lossless
line.

Jeff

That is what I mean Jeff. If there is any SWR, by changing the length of
the line, the voltage/current changes in such a maner that at certain points
you may get a 50 ohm match at that point.

https://en.wikipedia.org/wiki/Standi...dance_matching

"if there is a perfect match between the load impedance Zload and the
source impedance Zsource=Z*load, that perfect match will remain if the
source and load are connected through a transmission line with an
electrical length of one half wavelength (or a multiple of one half
wavelengths) using a transmission line of any characteristic impedance Z0."

This wiki article has a lot of good info in it. I have seen a lot of
stuff posted here that this article directly contradicts.... I wonder
who is right?

It has been my observation that when the subject matter is long established
science, such as transmission line theory, wiki is normally correct.

Why do you ignore it when it says Zo is the impedance of the
transmission line and not the source?

I don't; The transmission line in this case IS the source.

The SWR in a system, any kind of system, is measured at a point in a system.

One side of that point is the source and the other side of that point
is the load.

It also does not matter which side you declare the source and which side
you declare the load.

A 50 Ohm source and a 100 Ohm load has the same SWR as a 100 Ohm source
and a 50 Ohm load.

By convention the load side is normally taken as the side which, when
the system is powered, the power is desired to be dissipated.


--
Jim Pennino