On Fri,3/31/2017 12:53 PM, Edward Mccann via TowerTalk wrote:
Jim:
What is spacing between your two wire elements?
They're not parallel, roughly 20 degrees difference in azimuth, and they
are rather widely spaced. At one point I did the trig to figure it out,
but don't remember. Looking at the the View Antenna screen, I'd estimate
75 ft between the centers. The dipoles are where they are because that's
where the trees that hold them up allows them to be. :)
Steve talked about SWR bandwidth. I'm FAR more concerned with the gain
bandwidth. From the modeling I've done, that's improved by wider
spacing, and so is SWR bandwidth. SWR bandwidth can be improved by
making the DE thicker (that is, multiple wires with spacers).
Another thing I've learned from extensive modeling is that the height of
the reflector relative to the DE isn't very critical -- +/- 20 ft seems
to have no effect. But the height of the DE matters a lot, because
that's what determines the vertical pattern. The effect of the dipoles
being non-parallel is simply to skew the horizontal pattern.
73, Jim K9YC
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