Your results might not be the same  but changing the amplifier that you plug in to an outlet made all the difference.   We'd struggled off and on since we put on the metal roof in November.   Blamed the new roof for problems with the attic antenna.  Just couldn't figure out why we had so many problems with the outside antenna.  New scans are getting us the 15's,  and it has GRIT TV that we lost when channel 4 disappeared.