Hi Hal,
> As I understand it, there is a viewpoint that the vertical wire
> terminatons (this discussion applies to both ends) are a significant
> enough part of the antenna that they will degrade F/B and pattern.
> This effect being more significant as one goes up in frequency. I
> have done a fair amount of modeling with EZNEC, which supports this
> view -- as does ON4UN's book. The 'answer' to this view being the
That is a myth. Six feet of vertical drop is six feet of vertical drop,
no matter how you "cut it".
For an excellent example of this, look at the Pennant antenna. The
long sloped end of the antenna actually behaves exactly like as a
vertical, and radiates the same amount as the straight vertical end!!!!
If that did not happen, the antenna would not work! It would not be
directional. Since the antenna works, and works like a Flag of
slightly shorter length, we know the sloped end behaves like a
vertical.
A second example is the "K9AY loop". With two sloped ends, it
behaves exactly like two phased verticals.
> sloping of the last 50 feet or so of the beverage, providing a low
> angle termination that has negligible pick-up in the vertical plane.
> Sloping terminations are, however, not deer and people friendly ways
> to end the antenna.
They also don't do anything useful.
> I think there is an alternate viewpoint that it doesn't matter much,
> or maybe not at all, on 160M, where the vertical wire at around 9 feet
> of height does not introduce enough signal into the antenna to matter.
> Does this pretty well sum up 'conventional wisdom?'
Sums up what I have found.
It is absolutely physically impossible to cancel the vertical radiation
through additional conductors in the drop wire, or any reasonable
slope in the drop wires.
On higher bands, the solution is simply to lower the antenna or
install an elevated ground system.
73, Tom
(W8JI@akorn.net)
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