W5DXP wrote in message ...
David Robbins wrote:
but Vmax and Vmin don't occur at the same location on the line. when
measuring Vmax and Vmin you have to look 1/4 wave apart on the line... so by
definition it is a distributed measurement so losses do matter.

The measured 'rho' at any *point* can be determined by Sqrt(Pref/Pfwd).
That means, for lossy lines, measured SWR increases toward the load and
decreases toward the source. An open-ended 400 ft. piece of RG-58 will
show a near perfect SWR at the source end on 440 MHz.


I agree with both of you on this one.

This is why people will tell you that your SWR meter should really
be
at the antenna, instead of at the end of 100 ft. of RG-58, if you
wanna measure the SWR at the attenna!

Absolutely agrees with everything i know up to this point.

But, you SWR meter is at one point only! You don't have to
measure at two places 1/4 wave apart! This is because the SWR is
based on the forward and reflected powers.

But i agree, if you move 200 feet down RG-58 from the SWR meter at
the antenna, the SWR will most certainly improve!

My point is that the RC equation calculated the RC at one point,
and so the SWR equation will also apply at that ONE point.

But if you want to get the SWR 200 feet down the line, you will
have to
move the SWR meter and measure at the new location.


Slick