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Old March 22nd 14, 11:57 PM posted to rec.radio.amateur.antenna
Jon Danniken Jon Danniken is offline
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First recorded activity by RadioBanter: Mar 2014
Posts: 16
Default Discone and feedline grounding

Jeff Liebermann wrote:
Jon Danniken wrote:


I thought the discone/biconicals were more of a horizon-looking antenna,
at least from what I have read on them?


After I ran the NEC2 models, that seems true for the low end of the
frequency range. They are suppose to look something like a broadband
version of a vertical dipole. However, as the frequency goes up,
additional lobes appear until at the top of the frequency range, most
of the RF is going straight up. A Biconical is somewhat better than a
discone at retaining a sane looking pattern and reasonable gain, but
not much better.

My point about listening to aircraft is that there's little difficulty
hearing aircraft that are overhead, and plenty of difficulty hearing
aircraft near the horizon. Therefore, the antenna should have most of
its gain towards the horizon, and less gain above the horizon to near
overhead. At low frequencies, the discone does that. At the high end
of the range, it's quite the opposite.


Aha, okay I got you now, thanks for that. I still need to figure out
how to read the "lobe pattern" charts.

Maybe I'll look at a switcher of some sort eventually, and plan on just
manually doing it for now, thanks.


Ummm... climbing the tower to rotate a manual switch doesn't sound
like a good idea.


Hehe, indeed it doesn't. I was thinking more along the lines of a relay
box, if such a thing is possible, or maybe there is actually a gadget
that does something similar.

Along those lines, if connecting antennae of differing frequencies
together is not something that works, how does an antenna with multiple
different elements, like something like a scantenna
(http://i.imgur.com/D3Aeb58.jpg) get away with it?

Jon