Couple of web sites for you to check: http://antennaweb.org or http://tvfool.com. They will help you to determine the size of antenna you would need at your location to receive stations, and how many stations you should expect.
If you have an older analog set you will need a analog to digital converter. From the wikipedia, here were the dates established by the FCC which mandated tuners in television sets:
The FCC has issued the following mandates for devices entering the US:
By July 1, 2005 all televisions with screen sizes over 36 inches (91 cm) must include a built-in ATSC DTV tuner
By March 1, 2006 all televisions with screen sizes over 25 inches (64 cm) must include a built-in ATSC DTV tuner
By March 1, 2007 all televisions regardless of screen size, and all interface devices that include a tuner (VCR, DVD player/recorder, DVR) must include a built-in ATSC DTV tuner.
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