No such thing as an HD antenna despite some manufactures advertising such. They receive UHF or VHF, same frequencies as your old antenna receives. The antenna doesn't care nor process the type of transmission carried. Your TV does that.
That said, older analog transmissions were mostly on VHF while todays HD is mostly on UHF. Depending on city there maybe stations on one or the other or both. Some antennas do better than others at receiving both VHF and UHF but HD is irrelevant in antenna selection.