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Old October 5th 03, 05:23 AM
Cecil Moore
 
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Walter Maxwell wrote:
How then can the reflected voltage and current be other than 180 degrees
regardless of the load?


Consider a transmission line driven by two identical sources which are
signal generators with circulators+loads designated by SGCL.

SGCL1-----------50 ohm coax----------SGCL2

All the power sourced by SGCL1 is dissipated in SGCL2 and all the power
sourced by SGCL2 is dissipated in SGCL1. The system is perfectly
symmetrical. Will there be ordinary standing waves? Of course. The voltage
and current from SGCL1 are in phase. The voltage and current from SGCL2
are in phase. The only difference between the two currents is
Kirchhoff's convention. When the voltages are maximum at the same point,
they superpose to 2*V. When the two currents are maximum at the same point,
they superpose to zero because they are traveling in opposite directions.

We would say that SGCL2's voltage and current are 180 degrees out of
phase.

Someone looking at the experiment from the other side of the screen
would say that SGCL1's voltage and current are 180 degrees out of phase.

It is only a convention, one that doesn't exist for 3D light.
--
73, Cecil http://www.qsl.net/w5dxp



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