[NLRS] Favorite horizontal loop design?

[Dr. Gerald N. Johnson]

On Fri, 2007-07-06 at 11:54 -0500, Paul Beckmann wrote:
> 
> I'd like to make up a stack of 3 horizontal loops for 6, 2, and .7
> meters and am wondering what tried-and-true designs the NLRS crew
> might recommend. I'm especially interested in matching section
> designed used. I'd also like any advice on spacing that will keep me
> out of trouble. I'll likely build all of them out of copper
> pipe/tubing for fixed outdoor use. Not anything for great performance,
> just to have weak signal capability from the home QTH.
> 
> 73
> --Paul, wa0rse -- EN34kv

In a private e-mail a couple weeks ago, W6OAL (Old Antenna Labs) at
Denver told me he just made a three band loop, for 2, .7 and 1296 for a
ham there. Essentially he's telling me (without enough details to let me
duplicate it yet) that a stub fed horizontal loop (like the M2) for the
lowest band works fine on the third and 9th harmonics. I've spent a
little time with EZNEC modeling that scheme and while the 3rd and 9th
harmonic patterns aren't horrible, nor very circular, the matches aren't
horribly bad either. The gamma matched loops are sure to be single band.

Whatever, its not something that can be easily confirmed to work at a
typical ham run antenna test because the lack of directivity accepts way
too many reflections to make the test very sensitive to antenna
position. The none direction antenna pattern measurement demands the
most sophisticated reflection antenna range for any reliable results at
all.

It sure would be nice to have a multiband horizontal mostly
omnidirectional single feed line VHF/UHF antenna for back up at every
one of our stations for back up and for near local contacts. Most of the
time we work signals with our beams that have a lot better S/N than the
beam's gain so we should be able to work those paths with loops too, at
least on one end. And do it far better than from vertically polarized
omni antennas.

-- 
73, Jerry, K0CQ,
All content copyright Dr. Gerald N. Johnson, electrical engineer