Tam/WB2TT wrote:

"Cecil Moore" wrote:
The actual SWR on a lossless line doesn't change. Yet, in another
posting, I showed that moving the Bird 1/4WL closer to the load
caused a reported SWR change by the Bird from 1:1 to 2.25:1. How
could both results possibly be right?

The Bird does not know squat about transmission lines, foreward, or
reflected. It only cares about impedance. If you connect a 50 Ohm load to it
through 1/4 wave of 75 Ohm coax, the impedance the Bird sees will be
transformed to 112.5 Ohms; hence the 2.25 SWR. (Actually, a 2.25:1 impedance
ratio)

Yes, that's exactly what I said in the other posting. But some
people seem to believe that inserting a Bird into a transmission
line with a Z0 other than 50 ohms magically changes it to a 50
ohm environment. The 40mm of transmission line inside the Bird
is supposed to accomplish that miracle.
--
73, Cecil http://www.qsl.net/w5dxp