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Here's my first attempt at building a vhf 2 meter
copper loop
antenna. This was my first time using
a propane torch to weld.
This antennas was constructed using 1/2 inch cooper tubing which can be
found
at any home building
supply or plumping supply store. My soldering job with the propane torch was
pretty bad when building the first antenna. I then decided to build
a second antenna and phase them together to get more gain from the
antennas.
This antenna was designed to work in the 2 meter SSB portion
of band. Although you can tune it to work
in other portion of the 2 meter band.
The 2 meter
square loop is a folded Dipole around itself.
The shape is 11" X
11"
Constructing The Antenna:
Fig 1:
This is optional.
How ever I found it to be very helpful when it came down to fine
tuning the antenna. The first thing I did was to make the tuning
tips for the antenna. Using copper end caps and drilling a hole for
a #8 x 32 brass screw. Then welded the brass nut to the
inside and outside of the end cap. Be very careful not to let
solder run on the inside of the brass nut. If this happens you will
not be able to screw in the brass bolt. You will need to
make two of these. Then used one additional brass nuts to lock the
bolt in place once tune. You will need three brass nuts and
one screw for each cap. Use a 1 1/2 inches long brass
bolt.
 Fig 1.
Parts Needed:
1/2 Inch Copper
Water Pipe
Long Sides 9 1/2 inches
Open Ends 3 1/4
2 Short Pieces on each side of "T" 4 7/16
4-90 Degree Elbows
2-Copper Caps
1 Copper Tee
Brass Plate for SO239
Gamma Tube 4 3/4 of 3/8 Copper Tubing
RG8 Coax used to make Gamma Match 5 1/2 inches long
Copper or Brass Tubing For Gamma Bracket.
1
SO239 Connector
Tools
Needed:
Propane torch
Solder
Gloves for handling hot cooper tubing
Drill & Bits
Screw Drivers
Pipe Cuter
A vise if you have one works great for hold tubing in place
while soldering.
Flux
You will need to cut two piece of copper
tubing 9 1/2 inches long and weld two elbows to each end.
Next you'll need to cut 2
pieces of tubing
9 1/2 inches long. You'll need two short piece 4 7/16 inches
long which will be used to connect in the T fitting. The open
ends should be 3 1/4 inches. Solder a elbow to each end of the 9
1/2" tubing. Then solder one end of the 4 7/16 pieces to each
elbow. After that you will then need to solder your T connector
to each end of the 4 7/16" tubing.
Next you'll need
to solder the coax connector bracket to the T connector.
Now you need to
make the gamma matching network. For my gamma tube I used
aluminum because that's what I had laying around. The gamma
tubing measure 4 3/4" long from a 3/8" tubing.
You'll need to solder a 5 1/2" piece of RG 8 coax to the
center connector of the SO-239 connector. When using the RG8
discard the outer shield and use only the Dielectric. Slip the
RG8 inside the 4-3/4 Gamma Tube. You will also need to make a
strap to hold the other end of the gamma tubing. This is also
used to tune the antenna. The Gamma bracket should be at least
1 1/2" long brass or copper. Secure with stainless steel screws
right before the 90 degree elbow. The Gap between the Open Ends is
2-3/8". Adjustments to the gap in or out can be made with the modification
of installing the brass screws on the end caps.
This antenna is
11
x 11 in
size. Good luck with your 2 meter loop project
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