If you have a modern (LCD) tv then you do not need a converter. There is no such thing as a digital/hd antenna just antennas that are better at receiving UHF channels. Do not bother with an indoor antenna if you are mostly in the boonies. You want an antenna that is above things that can block signals.
You don't say was brand of roof antenna you have now. But if it is a Winegard Batwing then you could swap it for a new version such as the Rayzar Air. You have several options with Winegard, so go to their website and check them out.