As long as your HDTV has an ATSC (digital) tuner, you should be able to pick up your local channels with just an antenna. If your HDTV only has an NTSC (analog) tuner, you will need a converter box.
Go to antenna web and enter your zip code and click the submit button. On the next page, move the house icon on the map to your location and click continue. This should give you the list of channels available locally.