When I disconnect the antenna, I still get the static
Then the problem has nothing to do with the antenna. It is either a radio problem, or something in the vehicle is generating RFI on the power leads even when the ignition is off. Try putting a filter on the power leads like this one:
https://www.amazon.com/Magnum-XLF-20BP-Common-Power-Filter/
If that doesn't fix the problem, you need to get your radio fixed.