Range Expanders

My library has open WiFi but they are half a mile from my house. Is there a range expander which could reasonably expand an open signal that far?

I was looking at a "sniper" box which boasts a two mile range but it appears to be for hacking and I don't need that.

 

A Cantenna may work http://en.wikipedia.org/wiki/Cantenna Can be a old Direct or Dish with the Can pointed at it, to help get a broader range of grabbing the signal. On the other hand, you may find that you will pick up more signals than you expect, both opened & closed.

inSSIDer works for figuring the -db level of any signals that you are picking up. More info http://www.wikihow.com/Make-a-Cantenna http://search.yahoo.com/search?ei=UTF-8&fr=crmas&p=Cantenna