Okay, some of you might be stuck with HAVING to use the attic for your OTA antenna, but boy oh boy does it cost you signal strength and cause a bunch of other problems. If you are thinking about it or you have no other choice, at least be aware of the situation at hand. I saw a great post about antennas in attics on another forum that linked to a post on another forum from Bob Chase, a broadcast technician who regularly comments on OTA antennas and stuff over on AVSForum:
So, there's no substitute for an outdoor roof or mast mount if at all possible. And as far as good signal reception is concerned, remember what the fighter pilots say: "Altitude = Options".Attics take a huge toll on the signal you get. The few that I have measured so far have been in the 20 dB range of attenuation. Those attics are made of standard asphalt shingles, over roofing felt, over plywood type construction. I have not been in an attic like yours.
Attics also cause reflections that the HDTV tuner has to equalize out and there is only so much equalization that is available. So that means there is less equalization available for the 'real world' multipath that is arriving over your house.
Some folks have good luck with the Channel Master CM7777 preamp. Inside the attic it is pretty hard to overload the front end of that particular amp. (Outside it can happen quite easily.) Given the right conditions, preamp will not overload but the output of the amp can overload the HDTV tuner . That is just one of the good reasons for using an attenuator at the receiver.