Walk around outside with the whip extended and see how the interference and
noise is. If it is much less, but you're still close to the fan farm, then
you may be dealing with interference inside your home.

The best approach, if you have the right property size, is to run a wire as
far away from the restaurant and your house as possible (on top of a wooden
fence works), and use a balun (you can use a TV matching transformer for
now) and feed it into your house with coax. For your application, outdoor
TV 75 ohm coax will do, and you can get an adapter for the end to go to the
mini-plug. Radio shack sells everything you need. Don't forget to ground
the shield with a ground rod.