> Somebody had to be first, and Mr E Clark Quackenbush [1] did a fine
> job... for its time, which was in the 1930s. But it's important to
> remember how long ago that was.
That ties in with why we have a 50ohm coaxial line standard for most 2way
communications purposes and it probably dates back to the Quackenbush era.
50ohms represents the mean value between 30ohms for best peak power
handling and 77ohms for lowest loss. The arithmetic mean is 53.5, and the
geometric mean is 48 ohms. Roughly split the difference and round to the
nearest whole number and we get 50ohms.
When the application is Rx only, all else being equal, 75ohm lines offer
the lowest loss for a coaxial cable and the reason we see this Zo for CATV,
Satellite TV, overtheair VHF/UHF reception, etc.
Paul, W9AC
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