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An Easy to Install Vertical Loop for
80-6 Meters
by John Reisenauer, Jr.
KL7JR
A previous loop article by Steve
Ford, WB8IMY (May 2002 QST, "One Stealthy Delta") caught my
attention, especially because I've had such favorable results with
other loops I've experimented with in the past. I
wanted an "easy to install" loop for my portable island operations.
One that was "long" enough for 80 meter work. I did modify
Steve's design a bit to more fit my needs (ie- longer antenna since
I'd usually have the real estate on portable outings and I wanted my
tuner closer to the rig).
My portable loop is 150 feet long
(50 ft per side) and includes a 4:1 balun at the feed point midway
on the horizontal side. A short run of RG-8X coax was all I needed
to reach my permanently installed tuner in my motor home (it
probably would have been better using a minimum coax length of 50
feet?). The loop only took a few hours to make and the cost was
about $20 for wire (I used #12 solid insulated house wire left over
from another project and scrap PVC pipe for the insulators).
Schedule 40 PVC pipe and fittings along with solid insulated
wire work better in cold temperatures according to my
experience.

Picture a triangle with one pointed end up for the
apex and the feed point in the center of the bottom horizontal
portion of the loop. It doesn't get much simpler than this. For
those of us who like to know how many wavelengths make up this 150
feet long loop (1005 divided by frequency in MHz):
28MHz (4.3 wl), 24 MHz (3.7 wl), 21 MHz (3.2
wl), 18 MHz (2.7 wl), 14 MHz (2.1 wl), 10 MHz (1.5 wl), 7 MHz (1 wl)
and 3.5 MHz (.5 wl).
On a long March, 2003 weekend outing,
It took me about 2 hours to set up the antenna, mostly because of
the irregular shaped campsite I was using with respect to tree
spacing and wire always tangles up when I'm around!
I was
only able to get the loop apex up about 30 feet (higher is better)
and one end of antenna was at 12 feet off the ground and the other
was about 6 feet, with the feed point about 7 feet "sloped" away
from the apex and bent in one direction (I made the antenna fit the
lot).
At a height of 40 feet or higher, the antenna would
more resemble a delta loop no doubt! I was confident this "sloping
loop" would work fine even though it deviated a bit from the
original design of three sides at 40 feet long each and didn't turn
out looking exactly like a triangle.
The loop loaded easily on all bands
10-80 meters with my new LDG Electronics RT-11 tuner and old FT-840
transceiver. It may even have loaded on 160 meters but I forgot to
try. I don't have 6 meter capability (yet!) so will take Stev''s
word that it loads on that band as well.
My results were:
15m K4, 17m JA and K0, 20m KL7, K2-K8, UR4 and VE3, 40M K6 and K7,
80M K6 and K7. There just wasn't a lot of DX on, but I managed to
work most every station I called.
I also installed my old Hustler 5 BTV
vertical to compare with the loop on receive. I knew what the 5BTV
could do and wanted to see if the two antennas differed much.
Since my motor home roof is metal, I put the 5BTVs feed
point at about 6 inches above the roof for a ground plane effect to
avoid installing elevated ground radials or to ground mount it
creating a safety hazard. (Close encounters with park rangers can
make for short camping trips)!
It only took about 15 minutes
to install the 5BTV. (Note: both antennas were mostly pre-assembled
to save time in the field). Both the loop and 5BTV received about
the same on 80-15 meters in "side-by-side" comparisons throughout
the 3 day test. Ten meters was dead each time I checked, so I
concentrated on the lower bands. I worked almost the same call
areas on the 5BTV as with the loop. On a few occasions, the 5BTV was
one to two "s" units better on 20m while the loop was also one to
two "s" units stronger a few times on 80m. I'm sure horizontal
to vertical (and vice-versa) polarization characteristics between
the other station's antennas and my antennas had much to do with it.
For the most part, both the loop and 5BTV were pretty much even
on receive. On a second outing a few weeks later, the bands were
more favorable allowing me to work a lot of DX on 17, 40 and 80
meters including KL7, KH6, H44, J88, TG9, JR3, PP5 and others plus
many stateside contacts with the loop. I was particularly amazed by
band conditions on 17 meters and how easy it was to break big
pileups! The loop went up a lot faster too at a more "antenna
friendly" camp site!
In conclusion, I was satisfied with
the results of my efforts experimenting with both antennas. For
long-duration portable outings, or fixed station use (if you have
the room), I'd go with the loop antenna simply due to the economics
($20 for wire vs. about $150 and up for a commercially made
multi-band vertical) and because I'm partial to homebrew wire loop
antennas. I highly recommend you read Steve's well prepared article
mentioned at the beginning. It laid the ground work for my
experimenting.
His Original article link by Steve
Ford, WB8IMY (May 2002 QST, "One Stealthy
Delta") is below:
www.sgcworld.com/Publications/Articles/237qst0502.pdf
73
John ~ KL7JR |