In 1996 I had a T-L antenna on the
wall for two meters, when one Saturday it fell to the floor,
breaking in two pieces. I decided to try a loop antenna and I
only had one mounting point on the paneling, so I used tape to
make a triangle, but if I used an equilateral triangle as in all
of the antenna books I would have to put a nail in the middle of
the paneling; not in the groove. So I used my MFJ 259 antenna
analyzer and when I changed the top of the antenna to another
groove, the VSWR and the resistance were OK. I then tried a
repeater that is about 20 miles away and voila full quieting.
Later I checked into the net and no problems; they said it
sounded good for an indoor antenna with a handy-talkie. It
stayed on the wall and is still there as my emergency two-meter
antenna. Then I decided to try the design on 40 meters and it
worked! After testing with a three-element beam and the delta
loop I then decided that there was not enough signal difference
to leave up the beam in the woods.
One Tuesday evening, I was net
control for our local ten meter net at 8 PM on 28.330. After
several check-ins, I was told that my signal was down, but
steady and readable. I looked at the VSWR meter and it showed a
one-to-one. I then looked at my antenna switch and knew what
was wrong; I was on my 40-meter loop. I switched to my
four-element beam and everyone in the net said I was back to
normal. After several months I checked the delta loop for other
bands and it had a three-to-one VSWR on the worst band from 40
meters to 10 meters that I can use.
On ten meters my beam is to the
East for the net. Before net time, I would listen to the South
for Florida and Georgia because some of our club members are
snowbirds and if the band conditions are good, they check into
After the 40 meter delta was used
on 10 and the VSWR was OK I then decided to build a delta beam
for 10 METERS. I decided to point it to the South, so I only
had to switch antennas instead of using net time to rotate my
beam. I used the same design and it worked OK. I added a
reflector and two directors to make it a four-element array.
With my beam pointed to the South, signals were the same on both
antennas, but the delta was picking up a wider beam width, so
when I moved the one end to another tree to fine tune the
direction I added two more directors and the beam width was
narrowed enough for what I wanted. Now I do not have to rotate
my beam all the time during the net.
The cost of my six-element delta
beam was only time; since the wire (you can use any size that is
on hand) that made up my three-element forty-meter beam was
recycled into yet another antenna in the woods. It is nice to
have three acres of tall trees to put my antennas in next to the
house. What I like about the delta loop is, it is fed at the
top. Frequency adjustments can be made on the ground. I used
two pieces of wire 1/2 wave long plus about one foot or more
extra on both pieces for adjustments. After the antenna is
tuned up, solder the wires where the adjustment was made. I use
plastic rope to support the antenna. There is yellow and brown
rope; never use yellow in the woods, unless you want it noticed
from afar. Brown blends into the trees and can hardly be seen.
At each element, tie the wire with a knot in the top support
rope to hold the spacing in the antenna. If the rope stretches,
don't worry--it will still work, since the spacing is always a
compromise. The lower two corners of the triangle are held out
with rope. Tie the rope around the wire so it will slide for
fine adjustments for lowest VSWR. The radiation pattern seems
to be both vertical and horizontal with this design.
Then I built another delta and
pointed it to the east for tests. Tests with two-element delta
and a four-element horizontal Yagi at my QTH, with a
four-element Yagi that is on a rotator at W3TO’s QTH about
twenty air miles to the east of my QTH. (This test does not
take into consideration any feedline losses because the main
purpose is a vertical to horizontal signal report test for dual
polarity in the delta antenna).
My radio is a Kenwood TS870S and
Jim’s (W3TO) is an ICOM 751A.
Horizontal Yagi to horizontal Yagi
Horizontal Yagi to vertical Yagi
Horizontal Yagi to delta – S9
Vertical Yagi to delta – S7
The lowest S meter reading with
W3TO’s four-element Yagi being rotated and the delta was S3.
This shows that the delta has an
S7 gain and an S3 gain over the Yagi for DX purposes on fadeout
conditions, that is caused by polarity change. The impedance is
50 OHMS and the VSWR is non-existent with the .4 - .2 - .4
isosceles triangle with no matching network.
Dimensions for Delta Loop Antenna by WB3AYW
Add 5% for reflector
Subtract 4% for each director
ARRL Antenna Book
Edward M. Noll, 73 Vertical Beam
and Triangle Antennas
VE3GEJ, 73 Magazine, June 1972.
"Six elements on twenty meters. pp 17-20
My thanks to W3TO for testing and
for the reports from N4WCK in Georgia, WA3PGL and W3AGF in
Florida for signal reports, as this antenna was developed and
WA3HDK for his support