Cecil Moore wrote:
Fred W4JLE wrote:
Assuming I have an antenna that is perfect on 3.8 MHz. Perfect being
defined, as I am feeding it with exactly 1/2 electrical wave length of 50
Ohm feedline and it is 1:1 SWR measured at the source end.

What would the SWR be if I substituted the 50 Ohm feedline with a 1/2
wavelength of 72 Ohm feedline?

The SWR on the 72 ohm feedline would measure 1.44:1. You do
have an SWR meter calibrated for 72 ohms, don't you? :-)
Your 50 ohm SWR meter will measure 1:1, but as Reg says,
it is merely measuring the degree of match to your
transmitter designed for 50 ohm loads.
--
73, Cecil http://www.qsl.net/w5dxp


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It was stipulated in the original post that the swr was being
measured at the source end for the 50 ohm line. If all one changes is
the impedance of a 1/2 electrical wavelength line, and nothing else,
the answer is 1:1. Did not say anything about measuring the swr
anywhere but at the source. Whatever the antenna Z is in the 50 ohm
example that gives a 1:1 match, determines the swr bridge
characteristics. If the antenna Z was 72 ohms, then the bridge is 72
ohms for a 1:1 match. Change the transmission line to 72 ohms, still a
1:1.
Gary N4AST