You can also look into getting a more "directional" attenea. A parabolic is kinda expensive but it offers more direct signal and some of them you will have to either be in the line of sight or behind the tower.

You other choices are yagis, and sectional. Sectionals are not a good choice since they are expensive and spread out the signal more. Yagis narrow it down a bit but still have a spread to them. They are less expensive and you may even find ways of building them yourself (I've seen them made out of Pringle cans)