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Old September 26th 03, 07:22 PM
Roy Lewallen
 
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No. The voltage reflection coefficient is the ratio of two voltages, and
has nothing to do with their directions. The reverse voltage wave is
always traveling toward the source. The forward voltage wave is always
traveling toward the load. The angle of the reflection coefficient is
the relative phases of these two at the point the reflection coefficient
is being evaluated. It makes sense to speak of the reflection
coefficient as having a "sign" only in the two special cases of zero and
180 degree angles. Otherwise, it has an angle, not a positive or
negative "sign".

The current reflection coefficient is a little more ambiguous because of
the freedom of defining which direction represents positive flow of Ir.
If Ir is defined to be positive toward the load (the more common
definition), then the current reflection coefficient, Ir/If = -Vr/Vf. If
it's defined to be positive toward the source, then Ir/If = Vr/Vf.

Roy Lewallen, W7EL

Jim Kelley wrote:
"Cecil Moore" wrote in message
...

Jim Kelley wrote:

Since rho represents the fraction of forward voltage that is reflected,
what does a negative value for rho indicate?


rho = +1 means there is a zero degree phase shift in the reflected


voltage.

rho = -1 means there is a 180 degree phase shift in the reflected voltage.



So in other word the sign sometimes indicates phase, and other times
indicates a direction in propagation depending on which hand is waving..
Thanks.

73, Jim AC6XG



 
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