Here’s a public service announcement from the friendly Consumer Electronics Association and National Association of Broadcasters: Move your TV antenna way from the TV for prime DTV reception.
The two organizations are both stating that this should improve reception, especially in urban areas on channels 2-13. It is sort of ironic that TVs themselves can cause interference but apparently they do just like other electronics. The CEA and NAB both recommend moving the antenna as far away from the TV as possible and to use a VHF/UHF type.
It’s definitely worth a try, but if you TV signals are coming in just fine and the antenna is chilling on top, leave it alone.