Depends if you are looking to extend in at your home, or lots of other places. You can do a google or amazon for wireless extender for your home. Place it near where you tend to use your ipad for a stronger wife signal.
What sort of router are you using? I know in my house for a variety of reasons it is hard to get a wireless signal. In cases like ours, I purchased an airport extreme (an apple router) and a airport express (extender.) The express actually receives then re-broadcasts the signal. Just place the express where you have difficulty getting the signal, it may take some movement to the best location.
The link you posted would not work because of the iPad's lack of USB port