Externally boosters for 4g?

Any idea if this works for evo v and how good it works cuz I only get 1 bar at the house close to the window and I would love to see if i least 2bars or more not drop signal then when I tether I don't lose connection all time thanks for any help or any ideas to make one my self there radio shack close by here's the link I found
http://www.evdoinfo.com/content/view/3453/63/

 

Theres one for 50 im sure not just one phone boosted Or maybe make one?