On Feb 24, 8:16*pm, Owen Duffy wrote:
steveeh131047 wrote in news:f6f2c446-5128-4851-aab2-
:

Here's a write-up of an experiment I did to produce low Zo balanced
line. I didn't measure the loss because my application was for a very
short run:

Steve, you haven't let on much detail about the application of your low Zo
line.

I think I suggested elsewhere that you could fabricate such a thing with
parallel coaxes with all of their shields at each end bonded.

I explored using square tubes as a rigid transmission line. This finds
application in a range of areas, eg the boom of a LP. Seehttp://www.vk1od..net/calc/tstl.htm. A 50 ohm line (if that was your
objective) requires an air spaced line of 1.19 D/d. The article contains a
calculator to solve the curve fit.

Owen

Owen.

The application is no secret - the first paragraph in my linked page
explains it.

I was looking for line with a Zo in the range 50ohms-70ohms that could
be used for the band interconnects on the hexbeam. Arguably, balanced
line would be easier to handle, and might have some common-mode
advantages. Total length is about 4ft so loss is not an issue. It
would need to be very easily replicated, using materials readily
available to constructors world-wide.

At the end of the day it became more of a "self learning" exercise
than a serious quest !

73,
Steve G3TXQ