[Asphyx]

Doesn't matter how far away the tower is...
If your area is a hilly area or has lots of trees it will cut down the power of your signal quite a bit.

Not much you can do about it really...even a repeater will have issues unless you put up a pretty sizeable tower...

I used to live in the catskill region of NY. The Hills there would kill the signal (lots of dead spots) and they had ordinances in every town stopping anyone from putting up more towers to get the coverage.