Thread: SWR again.
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Old November 29th 05, 01:56 AM posted to rec.radio.amateur.antenna
Owen Duffy
 
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Default SWR again.

On Mon, 28 Nov 2005 23:52:40 GMT, Cecil Moore wrote:

Owen Duffy wrote:


that resistance. That measurement does not tell you the "impedance
terminating the transmission line" unless the line is of zero length.


A transmission line transforms the impedance in a predictable
manner given the transmission line specifications. One can
backtrack the SWR spiral on a Smith Chart to get a reasonable
estimate for the antenna impedance. The impedances for my dipole


To do that, you need to determine the position of the standing wave
pattern with respect to the load, and a typical reflectometer style
SWR meter does not do that. You could put a ruler to the line, but you
are using another instrument to make a another measurement that the
reflectometer could not make.

It is misleading to suggest that a reflectometer style SWR meter alone
is useful for determining the impede dance of a load connected to the
meter by a length of transmission line, save possibly the case when
VSWR=1 and the line is low loss and Zo is the same as the calibration
Z of the SWR meter.

Owen
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