On Tue, 17 Feb 2009 18:33:12 -0500, Robert Carroll wrote:
>How do you load it on the top?
As a Tee -- I have the top horizontal section suspended between
two trees, just as you would a dipole, and the vertical section is
connected to the center of the horizontal section.
There are lots of ways to do this, depending on what supports you
might have available -- I have a lot of trees. If you have enough
supports, you could have more wires on top but they could be
shorter. You can think of the top as simply capacitance to ground
that you're adding.
If you can support a rigid pole of some sort, you could put a
large ring at the top with small wires running out to it.
Or you could tie multiple wires to the top of a rigid pole and
pull them back down toward the ground like guy wires. The wires
would have insulators at some distance from the top so that only
the tops of each wire would act as loading. And so on.
The NEC program is a VERY good way to play with various wire
lengths without having to do too much experimenting. That is, try
modeling some configuration of wires that you can build and play
with lengths until it looks like it is working well. That's what I
did, and the antenna I built worked just like the model said it
would! You get a fairly simple version of NEC that can model
something like this free with the ARRL Antenna Book!
73,
Jim K9YC
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