[TowerTalk] One of our own...

[David Gilbert]

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 at 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 at contesting.com
>> http://lists.contesting.com/mailman/listinfo/towertalk
>>
> _______________________________________________
>
>
>
> _______________________________________________
> TowerTalk mailing list
> TowerTalk at contesting.com
> http://lists.contesting.com/mailman/listinfo/towertalk
>