Dave,
Wow, forget to take your medication ?
Bob
K6UJ
On 5/25/16 12:20 PM, David Gilbert wrote:
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
_______________________________________________
_______________________________________________
TowerTalk mailing list
TowerTalk@contesting.com
http://lists.contesting.com/mailman/listinfo/towertalk
_______________________________________________
_______________________________________________
TowerTalk mailing list
TowerTalk@contesting.com
http://lists.contesting.com/mailman/listinfo/towertalk
_______________________________________________
_______________________________________________
TowerTalk mailing list
TowerTalk@contesting.com
http://lists.contesting.com/mailman/listinfo/towertalk
_______________________________________________
_______________________________________________
TowerTalk mailing list
TowerTalk@contesting.com
http://lists.contesting.com/mailman/listinfo/towertalk
|