Towertalk
[Top] [All Lists]

Re: [TowerTalk] Loop v. Dipole

To: towertalk@contesting.com
Subject: Re: [TowerTalk] Loop v. Dipole
From: jim Jarvis <jimjarvis@optonline.net>
Date: Wed, 25 Jun 2008 09:40:29 -0400
List-post: <towertalk@contesting.com">mailto:towertalk@contesting.com>
>

> Do you think one could put a decent loop on a suburban lot
> that is only 100 feet by 60 feet?   How big a loop and how high
> do you suppose it might have to be?  I figure I could put something
> up that is a total of, say, 250 feet around.   I thought that might  
> just
> get me on 80 meters, and I could use a tuner for some higher bands.
> Using a 40 foot metal mast, I might be able to get it up that high at
> a reasonable effort and expense.
>
> Do-able?  Worth doing if so?
>
> Whaddaya say?    ///  JHR - K8JHR  ///
>

You need to be more specific about the loop design.
Horizontal square loops,  delta loops,  vertical square loops all  
perform
differently.   In fact,  depending on the geometry, and the feedpoints,
each of them can be made to perform differently.

A delta loop with its horizontal leg closest to ground will work as a  
low angle
antenna if fed 1/3 of the way up from one of its lower corners.     
Feed it in
the middle of the horizontal leg,  or at the apex, and it will be a  
cloud burner,
unless well above ground.

Horizontal loops are well discussed in the handbook and antenna  
book...they work
well, but you need reasonable geometry.  2 wavelengths at the lowest  
frequency.

Square VERTICAL loops are another matter.    These can be viewed a  
number of ways,
from as simply as center fed at the top, to fed at one of the lower  
limbs.   I used to work a guy
on 40m who chased dx using a square vertical loop, fed in one of the  
lower corners.
The lower wire was maybe 15' high, and the upper one 40'.    I don't  
remember the length of
the horizontal legs.   The dimensions are critical, though, because  
he got significant gain on
40 from this 80m loop.    He would routinely be as loud with the loop  
as I would with a 2 el
yagi @ 70' into EU.    And often he'd outperform me into Asia.

Thanks for asking the question-- I've been contemplating what to do  
in a suburban lot for
lowbands, and had forgotten the vertical square loop.

n2ea





_______________________________________________



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

<Prev in Thread] Current Thread [Next in Thread>