As far as an antenna is concerned, a signal is a signal. It doesn't
know anything about analog or digital.
That said, you do need the right type of antenna. Most digital
broadcasts (not all digital is HD) are UHF. The typical two-pole 'rabbit
ears' are only for VHF (2-13). Just because the analog is on VHF doesn't
mean the digital version is. Here in Chicago, the only VHF digital is
WBBM-TV/WWBM-DT (analog 2, digital 3). UHF usually uses either some form
of round antenna, or those arrow-shaped directional things like the
often mention 'silver star', or bow-tie shaped, sometimes with a
reflector (grid or similar behind bow-tie) behind it.