Go to a radio shop and have them build you one to these specs.
~4' whip antenna tuned to 152.5 mhz, 3db gain,magnetic mount, with a female SMA connector. That's what I did, and this is a picture of my first test run with it. In case you can't see it, it is reading 7 miles. I have not had them range that far this spring, but I have picked them up several times at 2-3 miles.
