"Jerry" wrote in
news:dniDj.714$Nr1.510@trnddc01:

....
Hi Owen

I have no disagreement with your thoughts. I do want to point out
that
the short helical antenna named Quad Helix does give good CP normal to
the helix axis.

Hi Jerry,

John Kraus' explanation of "normal mode" is where the radiation normal to
the helix axis dominates. On that basis, the Quad Helix (which he
discusses in his book) is neither an axial mode helix nor a normal mode
helix, it is large enough that it has significant radiation both normal
and axial, but not large enough to be dominated by the axial lobe, and it
is a multi-filar helix which allows CP normal to the helix axis.

The Quadrifilar Helix is an interesting antenna, and I was aware of your
particular interest from previous reading.

I don't know of a mono-filar normal mode helix that gives CP, but I
expect that two of them with phased feeds could be used in the same way
as crossed dipoles.

We are of course all guessing what Art had in mind, there is a conspicous
and familiar lack of coherent detail.

Owen