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,
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
The performance of
this antenna depends entirely on the
The rest of this article is by K5AXN!
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
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
The stations I work are about 200 to 300 miles out.
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
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 METERS!
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.
Check SWR and tune for your frequency. You can scale
this antenna for 160 meters or 75/80 meters but NVIS will not work above
Editors note from
"I talked 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 signal!
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
He tried several different type antennas during the QSO and the
NVIS WAS THE BEST with much stronger signals!"
The drawings below represents Jerry's
(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
Here is the layout, of the antenna he uses below re-drawn
from his letter.
Note that in the drawing above (not to scale) that you
from above and at a slight offset angle!
Another view below that may be helpful to visualize the
Drawing not to scale!
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.
many thanks to Jerry, K5AXN, for sharing this project with the Ham
Sorry! Jerry doe's not have email!
project and contact him on the air!
probably hear you!
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