"Reg Edwards" wrote:
There is a 50 ohm line feeding a 100 ohm antenna.
There is an SWR meter located at the line-antenna junction.
The meter has a reading. Does the reading apply to SWR of the
antenna, or does it apply to the SWR along the feedline?
______________

It applies to the match of the RF network that follows the SWR meter to the
impedance for which the SWR meter was calibrated.

And if in your example the SWR meter has been calibrated for 50 ohms, and is
moved to the input end of that line+antenna RF network, it will also have a
reading -- which will be the same as when it was inserted at the
antenna-line junction, less the round-trip RF attenuation of the
transmission line (assuming that the transmission line is 50 +/- j0 ohms
throughout its length).

In fact it is a common practice to optimise the transmission line/antenna
match of commercial FM and TV broadcast antenna systems by use of a variable
transformer inserted at the antenna input, whose adjustment is made by
reference to the far-end reflection seen at the sending end of the
transmission line, using a high-directivity reflectometer, or SWR meter.

The same physics applies to ham antenna systems and methods/means of
measurement.

RF

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