Radioshack (on line, if a store isn't convenient) has a graph about size of antenna and area of reception. I mounted one of their smaller "rural" antennas in my attic (so the outside of the house looks "clean" - amazing what a wife will insist upon), and took some time aiming it for best reception. It's a somewhat tedious process, with the antenna mounted on a standard 6' pole via a U-clamp at whatever height will clear your rafters. The base of the pole fits in a Christmas tree holder (no kidding). One person moves the antenna slowly in 360 degree turn in the attic, and someone else watches the TV (I ran 150 feet of coax from the attic to the room with the TV). When the signal is best, then the "attic person" walks to the area of the attic that's closest to the best reception direction, and that's it. My country place TV (a garage/apartment) has a high definition receiver, and I get not only the high definition versions of 2 of my 4 local TV channels, but also 3 PBS channels (I only receive 1 PBS channel on cable at my main home). Heck, football games look better on my "country" TV than they do on my cable connected TV at my "city" home.
GREAT excuse to go out to the country place in the later morning on a weekend, muck around with the tractor for a few hours, pop a beer and settle into a chair in front of the TV for a football game. Life is good.