It's ridiculous to say that a loop is always better than a dipole,
especially when your only evidence is one anecdotal example. There are
some solid theoretical reasons why a dipole might easily perform better
than a loop when the supporting structures for each are at the same
height. You can choose to be oblivious to those if you want, but the
kind of statement you just made is what made ham radio the petri dish
for unscientific speculation and bias in decades past. I thought we had
mostly progressed beyond that, but apparently not.
To be specific in your case, that narrow bandwidth for the dipole could
have meant that it was very efficient ... i.e., high Q ... although a 15
KHz bandwidth is unusually narrow and suggests that you had something
else going on. If you understood antennas you would have known that and
investigated further instead of just taking it down. Maybe you weren't
using a balun and had feedline interactions, or maybe your feedline
length just happened to be a problem for that particular setup. Could
have been something else as well, but it doesn't make a dipole
inherently a bad idea just because there was something wrong with yours.
Your loop likely has significantly higher losses since the bottom
portion is so close to the ground, and especially since a significant
portion of the polarization would be horizontal (tilted and bottom
corner feed). The higher losses would indeed make it tune more broadly
and would make it quieter, but it wouldn't make it a "better" antenna if
you were trying to actually radiate a stronger signal.
Dave AB7E
On 5/25/2016 9:01 AM, Courtney Judd wrote:
hey Steve, yes, I did enjoy the article about verticals/beach, very
educational! BUT, in the same issue of QST another article "If you can
hang a full-size vertical loop, then hang a dipole" really made me
roll my eyes. While I have never done any modeling, 50 plus years of
playing with various antennas leaves me with the opposite conclusion.
A loop is ALWAYS better than a dipole in my experience. I wanted to
spend some time on 160 some years back so I strung up a dipole at 110
ft with the resonant point at 1840.00.... worked great.... all kinds
of dx.... BUT the 2:1 swr points were only 7.5 kz up and down... even
with a tuner the antenna preformed poorly beyond that. It was just
un-satisfactory so i pulled it down and replaced it with the 160
antenna I still use today. A full wave loop fed at a lower corner, top
at the same 110 ft point. I did have to tilt it 15 deg from the
vertical to get it in the property lines but it works like a bandit.
It is quiet and broad banded: 2:1 is 1800 to 1890 and works well over
the whole frequency! I would NEVER replace it with a dipole. Well,
thats my 2 cents and I am sticking to it! lol, 73's Cort K4WI
K7LXC--- via TowerTalk <mailto:towertalk@contesting.com>
Wednesday, May 25, 2016 10:32 AM
Howdy, TowerTalkians --
One of our esteemed members, Grant, KZ1W, has had an article published
in the new QST called "Verticals On The Beach - Some Modeling Results".
It's a well thought out article with actual on-the-air performance
compared
to predicted modeling results. A real practical article for anyone
interested in vertical performance.
Cheers,
Steve K7LXC
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