Said something about this in another post, saw your post and thought it'd help here too..
http://forums.hak5.org/index.php?/topic/28868-should-i-upgrade-the-antenna/
Its smaller then what you might be looking for, but I'd bet you can get at least a 1/4 mile range. Probably more with line of site and some experimenting.
To get a longer cone shaped range, use the antenna you have on hand and get a wire mesh noodle strainer.
They are a $1 at the dollar store.
cut a 2 holes in the noodle strainer, maybe 1' away from the base or bottom of the screen.
I think a good rule of thumb would be to make sure the middle of the antenna is in the cone of the noodle strainer.
Your basic poor mans parabolic dish...for a $1.
http://www.instructa...Strainer-WokFi/
here's a different version of it from a trusted source:
http://www.backtrack...p?t=4268&page=8
(just look 7 posts down)
Google homemade parabolic dishes:
https://www.google.c...iw=1301&bih=684
sorry for not posting an original picture. I can always get one from the store and show you if you want, just dont have one on hand.
Promise you one thing though, your range will get some pretty damn good range with this.. So happy hunting ;p or phishing dare I say ;P