Hi John, yes it's possible to build your own antenna. I copied this information from another thread:
A quarter wave ground plane antenna is easy to make for less than $5. You'll need a soldering iron and solder too.
11 ft of 12awg solid wire(not stranded)
SO239 connector (Radio Shack No. 278-201)
Cut the wire into equal lengths of 23 inches
Insert one wire into center of the SO239 connector and solder it into place.
Make a loop in the other four wires and loop them into the four holes in the SO239 connector
Solder the four wires in place perpendicular to the center conductor wire.
NOTE: This will be about 70 Ohms. Ideally you want 50 Ohms. To get 50 Ohms you need to be at 135 deg from the center radial
Make a loop in the center conductor wire so you can hang it by string or rope.
This is a great attic antenna and it works very well. The 50 Ohm version is what I use for the KHSV feed.
Link to how to build it but use my wire lengths:http://www.hamuniverse.com/2metergp.html
I never tried this myself but I thought I'd pass it along. I hope this helps...