On 10/13/10 12:46 PM, Owen Duffy wrote:

It is not that I "don't like J-Poles", but that they have certain
characteristics that should be considered in their design and
implementation.

They are an 'end fed' antenna, and there is necessarily some common mode
current excited on the feed line / supporting mast structure. A balun
helps to reduce that, and I described an integrated balun that is an
elegant construction, though a further ferrite current mode choke would
be of benefit.

The big question I have always had regarding the balun was are we
reducing performance by eliminating feedline radiation? For a lot of
antennas, that may be a big part of the antenna system.

- Mike -