2 Meter 1/4 Wave Ground
By Dan, KE7TBB
Here is a very unique and
one of a kind 2 Meter 1/4 wave ground plane project using the base of an
Estes Model rocket launcher as a very portable support for 2 meter antenna fun. If you're into model
rockets and have an old launcher base just sitting around and want to put
it to work launching rf instead of rockets into the air, then read
The whole idea
behind this project is to utilize that old model rocket launcher that is
"just sitting on the pad" collecting dust, as a frame or support for
a portable 2 meter ground plane antenna. Now it will be used to "launch"
rf instead of rockets!
Parts you will need:
Estes model rocket launcher
no. 302215 (You may use other brands and models using your own
Copper wire. About 57 inches or so depending on your
S0-239 connector (optional)
soldering iron, solder
Nylon wire ties
Start by assembling the
launcher. When completed, remove the metal blast deflect plate and the
small black plastic tube attached to it.
Remove one of the legs.
the second opening of the leg insert the SO-239 connector.
JB weld or
hot glue into place the SO-239 connector leaving room for the solder
joints. Cut exactly 20 centimeters or 8 inches of wire. Strip and tin both
ends of the wire.
Remove the metal rod from the launcher and solder
the wire 2 centimeters or about an inch from the end of the rod. Insert
the rod back on to the legs.
Wrap the wire around the leg with the
SO-239 connector. Then solder the wire to the center of the SO-239
Now for the ground plane.
Start by cutting 3, 30
centimeter or foot long pieces of wire. Strip and tin one end only. Take
one of the wires and cut it 12 centimeters or 5 inches from one end
of the wire. Strip and tin both halves. Solder both ends to the outside of
the SO-239 connector.
Bend the long wire towards the end of the foot
and tape it or use nylon ties onto the foot. Bend the short
wire towards the center of the launcher. Tape it there but leave the very
end of the wire lose.
Solder the other 2 wires to the small wire and
tape them down the other 2 legs.
note: Vertical Radiator attaches to center of SO-239,
radials to outer shell of SO-239.
Tuning: For tuning, shorten or
lengthen the wire feeding the vertical rod or the rod itself as
Tip: For ultimate portability do not solder the wire
to the rod. Instead stick the rod and wire in the clamp together, that way
you can take the rod out of the base. Also take the legs off the clamp and
fold them together without breaking the wire. One more thing, the rod can
come apart in 2 pieces if needed for
is a 1/4 wave 2 Meter ground plane using the rocket launcher as a support
base for portability. Use your imagination and skills when building yours.
Remember that this project is nothing more than a 1/4 wave ground plane
for 2 meters and is not complicated, just tune the antenna lengths as
you normally would with a "standard" ground plane antenna. Tune for
lowest swr using very low power.
This is only one suggested method.
You may discover other methods using a rocket launcher. You can eliminate
the SO-239 and just attach the coax feed line at or near the base of the
vertical section as with any 1/4 wave ground plane construction. The
vertical section and the radials should be near 1/4 wave each as needed
for best swr at your center frequency. EXPERIMENT and have fun launching
RF on the 2 meter band! 73
Hamuniverse.com uses Green Geeks Web