I suggest a Winegard HD7084P mounted on the roof and No preamp. Pointed at 355 magnetic compass. This will get you the channels in the north type direction and WMYA 14 My Network will likely be received through the back side of the antenna because the signal is very strong. Read this about Real and Virtual channels.
http://forum.tvfool.com/showthread.php?t=695 . Also read this about placement of tv antennas. What it says is Yes you can put a Tv antenna and other antennas on the roof.
http://www.fcc.gov/mb/facts/otard.html . Also read this about tv antennas ,
http://forum.tvfool.com/showthread.php?t=237