Its most likely the antenna. Either the antenna or something is wrong with your Headunit. Go to bestbuy in the back of the store and ask them to take a look at it. They shouldn't charge you just to look at it. And I'm sure it's not that much work! Good Luck!
I'm planning on buying two 12" Fi Bl Subwoofers (Dual 1ohm or 2???) and I'm not to sure what kind of amp would power both of the subs together. Also on the Fi website you can select additional add-ons that you want with the subs. The add-on choices are, (1 or 2ohm) P Chamfer, Cooling, Flatwind...