Do not use a attic mounted antenna , you will not have any useable signal in the attic other then WRNN and WTBY. The neighbors will be very happy that you found a way to receive OTA Digital Tv , That Means They Can Also. Here is the Federal Law that says Yes you can install and use the antenna that is needed to receive reliable OTA Tv.
http://www.fcc.gov/mb/facts/otard.html