Your always going to get signal drop. Energy is ever depleting my friend. Also, you can get dead zone, interference, etc. In your case it sounds like you may have a type of insulation(foil backing) that is messing with it. You can get range exstenders, repeaters, etc, but what are your expectations? If you loose a bar every room, and if your looking to make it reach 3 floors, wireless may not be for you.
Wish I could give you specifics here, but I don't know enough about your network.