Once you determine which antenna you need, then go to the retailer and compare antennas. I would avoid ebay unless you understand how antennas work.
You could also look at some of the links I have posted in earlier posts on this thread. Also, there is nothing special required by an antenna to receive a digital signal. Antennas do not have to have any special design for digital or HDTV.
I just installed the DB8 Multidirectional Antenna and the ClearStream5 antenna and I get stations from the next state. Crystal clear better than cableTV. Do your research first and make sure you have good line of sight. The antennasdirect website has calculators to help you find the right antenna for your area....
I tried digital antennas, but most of them are just plain junk. Installing one in the attic our outdoors is the way to go for the best signal.