Two bays, well above ground, fed in the middle is about as good as can
be done. That is essentially what anonymous said. --- coax to a T and
equal runs from the T to identical elements ---

[Note that using this scheme with identical HF antennas that are not
many WLs above ground, will not optimize performance.]

As pointed out in a recent thread, the ring-and-stub antenna is
sensitive to small changes in dimensions. [very sensitive] If the
antenna is to be designed to be used where it is desired to have the
free-space vertical and horizontal patterns be close to each other (in
the horizontal plane), as in licensed broadcast applications, expect a
lot of tweaking.

On the other hand, if it is not important to "balance" the patterns,
most any balanced feed system will work to produce most of the gain near
the horizontal plane.

Recently, I was faced with the issue of finding an optimum spacing
of such an array from the face of a solid tower with a diameter of about
0.1 wave lengths. No hope, of course, in having the same real world
vertical and horizontal patterns. However, it was possible to find a
spacing that tailored the two patterns to an acceptable degree. The
modeling needed a very large number of segments!

For amateur use, just space the phase center of the most important
part of the antenna the magic 0.3 wave lengths from the tower surface
and point the antenna in the most desired direction. Fortunately,
because the most common amateur use is probably in conjunction with a
repeater, one would be advised to use good old reliable vertical dipoles
as the elements.

In short, in my opinion, you need to have a mighty good reason to
deal with ring-and-stub antennas. For amateur use, better options
exist.

73 Mac N8TT
--
J. Mc Laughlin - Michigan USA
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