The problem with those "Bow Tie" type and the big round Channel Master is this.
MOST over the air stations have moved to UHF, and those are very good to excellent UHF antennas.
But there are still a few VHF out there. I'm watching one as I type. and those UHF "HD" antennas fail to suck at VHF (Their job, like that of a vacuum cleaner, is to SUCK, in this case signals out of the air.
Speaking of vacuum cleaners.... Find the BC comics archive and go back 2 or 3 days (Today is 2/9/2014, I think it was 2/7 but I could be off a day)
Somebody Vacuumed.
Oh, Empty your mouth first.
I have seen some truly amazing antenna arrays.. Some folks like to bounce a signal off the moon and wait for it to return and they like to do it with what a TV station would call flea power.. I'm not quite into EME (earth-moon-earth) myself but would not mind chatting with the ISS. On Flea power.
To do that you need ANTENNA power.
But you can stack quite a few bow tie antennas on a reflector, if it's a parabolic so much the better,, And the more metal you put up there the better in all likelyhood.
BUT... There are other factors I won't bother with here.
BUT you still need VHF. At least VHF HI (Very few are still VHF low).