In article
,
phaedrus wrote:

Hi again,

Well I have read your informative replies on the problems with making
a low Zo twin feed with much interest. Clearly it's not really a
practical proposition. Shame.

So the obvious question is: why are transmitters normalised to 50 ohms
when clearly 450 ohms would enable us to enjoy cheaper, do-it-
yourself, lower loss feeders? Was this some oversight at the time, or
good practice for some obscure reason that I simply cannot think of?

As others mentioned, the origin is probably based on military standards.

It is my understanding that the lowest loss air dielectric Co-Ax would
have an impedance of around 75 Ohms. If you use the same mechanical
dimensions but with a polyethylene dielectric, the impedance becomes 52
Ohms.

Fred
K4DII