[Antennas] twin coax as shielded balanced line

[Gary Lee]

I had asked a question prevoiusly about the spencer dipole fed with twin
rg-11 as a balanced shielded feedline.

I have since read all the responses, and asked everyone I know.  Can't find
the referenced cq article from 1989, and haven't found a satisfactory
explanation on line.

The consensus seemed to be that this method of feeding could be lossy.
Could some kind soul please explain pros and cons without the use of
pictures as I am totally blind.

Tried the arrl antenna book, but the pictures were not well described on my
cassette copy.  This, it appears, would be a difficult job.

Thanks for any  help.