Install a Winegard HD7210P , multipath/ghost killer antenna above the roof aimed at 346 degree magnetic compass. Here is how to aim antennas ,
http://www.kyes.com/antenna/pointing/pointing.html. Also install a coax ground block , the best place to ground to is electric service ground. Grounding the coax shield , directs interfering signals to ground. The center wire of the coax carries the tv signals to the tv.