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A SUPER - GAIN ANTENNA PROJECT
FOR 40 METERS
Submitted by K5AXN, JERRY BARRY,
Taken from original
plans published October 1969 in 73 Magazine
Ed Dusina, W4NVK,
Editors note: Some of the text description
below was taken directly from the original article and has been edited to
save space. The entire article can be found in an old 73 magazine dated
October, 1969. It can be downloaded here from Internet
The rest of this article is by
Many thanks to both and all those who helped with some of the
research and continued testing of this design. A modified version of this
antenna is being tested in Afghanistan to get local news into hard to
reach mountainous areas by the U.S. and Afghanistan
This project gives
enough information to build a 40 meter Super- Gain antenna designed to
help hams compete somewhat better with the foreign broadcast stations
which practically take over the band in the evening and night time. It is
based on the theory of super gain NVIS arrays, which reject QRM from low
angles and produces a very high angle of radiation.
design....still under testing by many hams but used by many....is
extremely simple, uncritical and offers large gain and QRM
The propagation studies and design work was done at Dusina
Enterprises in Melbourne, Florida.
The antenna is described as having
approximately 9 db forward gain and an average of 15db rejection against
low angle QRM. The antenna is useful up to about 200 miles radial distance
from the transmitter in the daytime and up to around 1,000 miles at
consists of a single dipole antenna placed very close to the ground and
above a reflecting "screen" so as to limit the radiation to 90 degrees +
or - 35 degrees approximately.
In the original article published in 73
magazine, it is nothing more than a simple folded dipole made from 300 ohm
TV type twin lead cut to the length of 63 feet 2 inches plus or minus 1
inch and is fed in the center with RG58 coax or some other 50 ohm coaxial
cable. Note that the author of this
article described below does not use a folded dipole but only a
simple dipole made from wire.
It is suspended tightly
between 3 supports (non-conductive) exactly 7 feet + or - 3 inches. If
metallic supports are used, it is suggested that nylon cord, about 3 -
4 feet on each side between ends and supports to reduce the effect
of capacitance on the ends of the antenna.
On the ground directly below
and parallel to the antenna, lay three reflecting wires of a non-critical
length 65 to 80 feet long. One of these is laid directly below the
dipole. The other two are spaced 6 feet from the center or dipole
portion of the arrangement and again parallel to the dipole.
reflecting wires can be laid on top of the ground for slightly better
efficiency and secured at ground level using nails bent into a U shape or
any other method you desire.
Feed with about 100 feet RG58, 50 ohm
Using the exact directions above should yield about 1.05 srw
at 7.250mhz and increasing towards band edges. Some tuning may be required
as with most any antenna projects for your favorite
Quote: W4NVK, "Due to the extreme simplicity of this
antenna and to its significant improvement in communications of this
particular band, plus its small size, I believe that if amateurs erect
such an antenna and test it for themselves, they will be quick to see the
value of it and by this means more use can be obtained from the 40 meter
band in the daytime, since it not only greatly increases the signal
strength of the stations communicating, but significantly reduces the QRM
leaving the state and rejects any QRM coming in from outside the
Quoted from the original article by W4NVK:
be seem from the foregoing description, this antenna is sufficiently
simple that every radio amateur can construct one. Although this antenna
is intended to be used mostly for short-range communications up to about
200 miles, due to the nature of the 40 meter band, short skip conditions
prevail much of the time at night and the antenna is then effective for
distances of 1,000 miles and sometimes more with full
OF THE REFLECTING SCREEN IS VERY IMPORTANT FOR THREE
1. ANTENNA IMPEDANCE WILL BE 50 OHMS only when
elements are cut as described with reflecting elements installed.
LESS THAN 50 PERCENT EFFICIENCY without reflectors.
UNPREDICTABLE PATTERNS, GAIN, REJECTION AND OTHER FACTORS due to
variations of ground conductivity at each amateur's
performance of this antenna depends entirely on the
NOW LET'S BUILD A 40 METER SUPER - GAIN
See the drawings
below for more visual perspective of the setup.
"I used Pvc at
the ends and center of the antenna to keep it exactly 7 feet 0 inches. Our
tests show 10db gain. W8SYD, had a 10db gain over a G5RV at 50 feet up, (a
160 meter G5RV).
The stations I work are about 200 to 300 miles
It is really COOL! I can copy and talk to
stations I do not even hear on my G5RV or the 14AVQ vertical
antenna. This antenna really knocks out the foreign broadcasts when
the skip is long. It was in the Oct, 1969 73 magazine.
My friend, Don,
K5ACX, told me about it.
DO NOT CHANGE SPACING.....MUST BE 7 FEET +
or - 3 INCHES.
DO NOT TRY TO ADD A
YOU WILL LOSE RANGE.....10db IS A LOT ON 40
I have a metal roof 12 feet away and power lines parallel
about 30 feet away so you may need more length than I did.
and tune for your frequency. You can scale this antenna for 160 meters or
75/80 meters but NVIS will not work above 40 meters.
Editors note from N4UJW
to Jerry, K5AXN on the air while he was using his NVIS antenna with
reflectors on 40 meters. I was using only about 10 watts ssb (8 to 10)
into a temporary inverted vee only up about 16 feet to the apex. (I guess
you could call my "antenna" a field day special and nothing to be proud
of!). Jerry was 5 9 plus about 10db into my Alinco DX 70 from San
Antonio, Tx to my QTH about 50 miles Southeast of Dallas, Tx. Great
I do not recall his power output for certain, but I believe he
said about 100 watts. I did not get a signal report from him, but it was
obvious that he heard me at least Q5!
He tried several different type
antennas during the QSO and the NVIS WAS THE BEST with much stronger
drawings below represents Jerry's installation.
(He used a standard dipole instead of the folded dipole in
his final installation).
He used 1
inch PVC for the supports and tied off at each end with rope to a tree and
a fence with coax laying on the ground.
He used a plastic wire tie in
the center to attach the coax to the support. In his hand drawn picture
sent to me via snail mail, he shows the coax going straight down the
center support and laying on the ground.
Using 29 feet 5 inches on each
half of the standard wire dipole, he is
tuned for 7.266mhz.
Here is the layout, of the antenna he uses below
re-drawn from his
Note that in the drawing above (not to
scale) that you are looking
from above and at a slight
Another view below
that may be helpful to visualize the antenna.
Drawing not to
drawing in this section is showing a view from directly
The spacing from the dipole to the reflectors is 7
The bottom section of the drawing is viewed from one end.
spacing between A to C is 12 feet.
As always, many thanks to Jerry, K5AXN, for sharing this
project with the Ham community....N4UJW
doe's not have email!
Build this project and contact him on the
He can probably hear you!
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