You're apt to get better results if you extend the wire out away from
the building, so that it's no longer inside the building's "noise
envelope". Perhaps you can dangle the wire off the far end of a fishing
pole?

If you're not too far from the roof of your building, it might be worth
asking whether you can locate a wire antenna up there. Find a couple of
ventilation pipes extending 10-12 ft above the roof, spaced 100 ft or
more apart and you'll be in good shape. Then just run a coax feedling
from the antenna to your receiver.

Steve