Don, the swr at the 100 ohm end of the 75 ohm coax is 100/75=1.333.
In the case the 75 ohm coax is 1/4 wavelength long the impedance at the
other end is 75/1.333 or 56.26 ohms.
The swr at the 56.26 ohm end of the 75 ohm coax 75/56.26=1.333.
The swr anywhere along the 75 ohm coax is 1.333.
The swr inside the coax matters because it determines the what the end
impedance will be with a given source impedance.
It is not so much that we "care" what the swr is, but knowing the swr just
makes it easy to calculate what the load impedance will be with a given
source impedance. It gives us a chance to use a little science instead
observing "the magic".
73,
Gerald K5GW
In a message dated 1/14/2015 2:12:46 P.M. Pacific Standard Time,
donroden@hiwaay.net writes:
> But, the swr inside the 75 ohm coax is still 1.333 at all points along
the
> cable.
No, not at either end.
Why does the swr "inside" the coax even matter when we are discussing
load and source impedances ?
Don W4DNR
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