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Old September 4th 03, 07:16 AM
Dr. Slick
 
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"David Robbins" wrote in message ...
sorry, no scanner here.

how do you get rho1? please give me the Zo and Zl to try out, i have been
playing for a while with the basic equations and haven't found a case where
either formulat gives rho1.

and of course if |rho|=1 then swr can never be negative.


I think Reg put it best:

"Dear Dr Slick, it's very easy.

Take a real, long telephone line with Zo = 300 - j250 ohms at 1000 Hz.

Load it with a real resistor of 10 ohms in series with a real
inductance of
40 millihenrys.

The inductance has a reactance of 250 ohms at 1000 Hz.

If you agree with the following formula,

Magnitude of Reflection Coefficient of the load, ZL, relative to line
impedance

= ( ZL - Zo ) / ( ZL + Zo ) = 1.865 which exceeds unity,

and has an angle of -59.9 degrees.

The resulting standing waves may also be calculated.

Are you happy now ?"
---
Reg, G4FGQ


If it were not for Reg pointing out this example, i wouldn't have
researched and corrected my original, "purely real" Zo post with the
more general conjugate Zo formula.

And i researched it because i knew that you cannot have a R.C.
greater than one for a passive network (you can only have a R.C.
greater than one for an active network, which would be a "return gain"
instead of a "return loss"), so i knew that when Zo is complex, my
original post must have been wrong.


Intelligent people can be close-minded, that is for certainly, in
which case, their intelligence is blunted.



Slick