phaedrus wrote in news:fe96541e-75fc-423a-8eb7-
:

I seem to recall that ladder/open-wire feeders are relatively high
impedance ~500 ohms. Is it possible to construct 50 ohm open wire
feeder and if so, what would the spacing be?

Such a low characteristic impedance requires very close spacing of round
conductors. Proximity effect which causes the current to mainly flow in a
small adjacent portion of the conductors at close spacing makes achivement
of very low Zo at low loss very difficult, and not very practical.

TWLLC at http://www.vk1od.net/calc/tl/twllc.htm will perform the
calculations for you, including calculating the matched line loss and loss
under mismatch conditions, but read the comments on the page re proximity
effect.

Owen