Topband: Vertical vs yagi
richard at karlquist.com
Tue Feb 14 14:09:38 PST 2012
> I had a 2-element 40-meter array up and in use for about 5 years. It was
> a simple system using coax phasing lines (Christman feed, if I recall
> correctly) and, even in light of some of the negative comments about
> this system, it worked very well for me.
> In my location (northern Nevada) the most useful aspect of the antenna,
> with the elements oriented at 75/255 degrees, was the ability to
> substantially null east coast QRM when working DX from The Pacific and
> Asia. My null, based on repeated observations, was, at a *minimum*,
> 20db. I don't believe you'll do that with a 2-element yagi!
Your vertical array is of the "driven" (not parasitic) type.
A 2 element driven array can, if properly tuned, have a F/B of 20, 30 or
even 40 dB at some particular angle. A 2 element parasitic array
can never have more than 10 dB or so of F/B. It is baffling to me
that virtually all 2 element 40 meter beams are parasitic. Driven
arrays also have wider bandwidth, which is an issue on 40 meters.
I can tell you that I have compared various inverted vees on 40
to verticals, and there seems to be little difference in performance.
OTOH, the advantage of my 3 element Yagi (MonstIR) at 33 meters
height over the inverted vee is huge, both in terms of transmitting
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