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Pictures on the left can be zoomed by clicking on them.
This
is probably the most simple and inexpensive antenna you could make for 23cm. It
has about 9 dbi gain, a 60 degree beam width with a clean pattern, and f/b
ratio > 25 db. The picture to the left shows the antenna oriented for
horizontal polarization. Here's how to make one:
Cut a #12 copper wire (with vinyl insulation) to 44cm. Remove 10mm insulation from the center, 5mm from the ends to facilitate soldering. You can use bare wire if you want; however, leaving the insulation does not degrade performance, and will provide some protection from weather.
Prepare
a piece of coax by stripping 4mm of insulation from the end (see right). I used LMR-400. On
one side of the center conductor, remove the insulation and braid so that you
can solder one side of the wire to the center conductor, and the other to the
braid on the opposite side. The other end of the coax can be prepared for a
connector of your choice.
Bend the wire into 2 quads. Each side will be 55mm, and
all angles will be 90o. The first bend can be at the 10mm stripped
section, as this is will be soldered to the center conductor of the coax. The
5mm stripped ends will be soldered to the braid after bending them horizontal to
same at about 45 deg away from their natural plane.
The reflector is a piece of hardware cloth (1/2 x 1 inch
mesh), about 8"x10". From the surface of the reflector, the driven element is
spaced at 22mm (not critical, just aligned for best match).
The reflector is fastened in place with 4 pieces of the #12 wire, about 25mm long. I crimped one end of each wire to the reflector and held it all in place with a small hose clamp.