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BUILD THE 10 METER
WONDERBAR ANTENNA
Hamuniverse.com presents good plans for the Wonderbar
antenna. We have had lots of requests for it.
I had saved the
plans from a couple of years ago from the Amateur Radio Lighthouse
Society web site and this article and all
the credit goes to them and Jim, K2JXW.. Have
fun!
The fabulous
homebrew
10 Meter WonderBar
Antenna*
SWR 1:1 over entire band, great DX,
rotateable by
hand, 8 ft long - build for about
$20!
12 ARLHS
NEWSLETTER • VOL. 4 • ISSUE 2 • SUMMER 2003
Do you need a
small, rotateable DX dipole for 10 Meters that can be made from an
old TV antenna in a few hours, one that works the whole band with
minimal SWR, yet has good performance, is light weight, and easy to
make?
The WonderBar is just right for you.
In the original
version (see November 1956 QST) the elements were made from a
discarded TV antenna. The corners were crimped, and nuts and bolts
were used to join the corners together.
At the feedpoint, two
standoff insulators were used to fasten the elements (at the
triangles’ apexes) and to mount the coil. I used thin copper tubing
instead of aluminum and soldered (with a torch) the corners instead
of using nuts and bolts.
I fastened the elements directly to a
piece of pressure-treated wood using stainless steel screws and used
solder lugs on the coil, screwing them under the elements.
My
cost was about $20 for the tubing and screws. I used a piece of
scrap deck pressure-treated wood; so cost there was nothing.
For
the coil, the original article suggested a B&W Miniductor
#3013.
Being cheap, I used regular #14 house wire without
insulation for the 12-turn coil. I wound it over a 1" diameter broom
stick 3" long. The article said to tap at 10-3/8 turns, but I
soldered my tap at 10-4/8 (=10-1/2) turns. (I cant even visualize
1/8th of a turn, let alone count it out!) For the 2-turn link I used
the same #14 house wire but kept the insulation on it and spread
it out over the center 1-1/2 inches of the larger coil.
Feed with
52 Ohm coax.
Drawing above is the layout of the
Wonderbar for 10 meters. The copper colored lines are the wire
"triangular loops" attached to the loading coil in the center of the
antenna.
You will have to rig some type of insulated support for
the wire elements.
A PVC frame supported in the center for a
rotor would allow "aiming" the antenna.
The pattern should be
broadside.
Figure 2 Drawing above is showing the overall layout and tap
point as described in article above. The copper color represents
actual bare # 14 wire and the tap point shown with little red
dot.
Black coil (insulated) wire attaches directly to coax feed
to shack and is wound over the center of the main
coil.
Result of all these
cheapskate shortcuts? - One-to-one SWR over the entire 10M band.
Pattern like a dipole with good side rejection. Rotateable with
large forward lobe. Total width 8 ft; so I also tried attic mounting
using screw eyes and hung down about 24" from the rafters using mono
filament fishing line. Naturally, this does not allow the array to
be rotated.
No change in loading or SWR was noticed. Same
excellent results on xmit.
Receive seemed to be about 1 S-unit
higher than my outside dipole, although I dont know why (probably
directive).
Because of ease of construction, low SWR with no-tune
across the entire band from 28.0 to 29.7, and the excellent results,
this antenna became very popular with the 10M crowd during the IGY
(International Geophysical Year) around 1957-58, a time when some of
the highest sunspot activity ever recorded occurred (making today’s
numbers look sick by comparison). Also because of its popularity,
there were follow-up articles.
Editor Notes:
This antenna can probably be
scaled up or down for the band of your
choice.
There
were no formulas for calculating lengths of triangular elements for
10 meters in this article.
If anyone has the old QST's referenced
above and finds any info that can be used in calculating lengths
that we can publish here, please email to
me.....n4ujw
at
hamuniverse.com
If you’re interested, here are some references to
pursue - all from QST magazine:
*Jim, K2JXW, ARLHS member
#001
November 1956, p. 32, original QST article
February 1957,
p. 43, WonderBar 2-el beam on a 5-ft boom
April 1980, p. 59,
WonderBar remembered
May 1981, p. 46, WonderBar 3-el beam on a
10-ft
boom
Interested in Shortwave listening?
Recommended
Excellent Reference books!
Passport to World Band
Radio, New 2007 Edition
POWERED BY
HAM
RADIO!
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