k9ay observed that vertical dipoles weren't very good antennas...
When challenged by EI7BA, he observed that his 40m inverted vee
@ 120' outperformed a vertical dipole with its top at the same height.
I'm sure that's true, but it's a very different animal than EI7BA's
160m vertical dipole
with only 55' of it running vertical.
Both Jim and John's experiences are valid. They're just talking
about different
animals.
Off reflector, I provided some feedback to the original poster on 3
variants of the
vertical dipole. No need to go into them here. However, it's
probably worth
observing that for situations where there are limited opportunities
for vertical height,
the FOLDED vertical dipole can be extremely useful.
This antenna is visible on the YCCC website, although it's called
something else, and
i can't recall what, at the moment. However, consider it to be a
U, on its side. The upper
limb of the U is at 60', for example. The lower limb is at 8' or
so. And they're connected by
52' of vertical wire, broken in its center, and fed as a dipole. I
won't go into feedline treatment
here. However, this antenna, and a 160/80 variant of it, have
proven quite useful in
contesting applications.
There is a 160m contest site at the NJ coast, where a backup antenna
has variously been tried
as an inverted L, a Tee, and most recently as a 'vertical dipole',
aka U. The L and Tee had
identical, elevated radials. The Ell worked ok. The Tee was a dummy
load, and the U has proven to
be by far the best of the bunch. This installation is approximately
3' above sealevel, adjacent to a salt marsh.
Likely no better ground situation on the planet. However, the YCCC
reports indicate that the U has
worked well over New England rock, as well.
I hope that adds clarity, rather than confusion.
Personally, I like the vertical dipole on higher bands, as well. On
40 and 30, with only 60 or 70' trees as
hoists, I've had good results with it. It snakes well into the tree
branches, where an inverted vee would
be hard to erect, and likely only at 50' when done. I've been able
to fold over part of the upper leg of the
vertical, pulling it out almost horizontal, and getting the high
current portion of the antenna to 40' or more.
N2EA
_______________________________________________
_______________________________________________
TowerTalk mailing list
TowerTalk@contesting.com
http://lists.contesting.com/mailman/listinfo/towertalk
|