shortstuff_mt raises a very good point. But watch out for the phrase "dual tuner". For example, as shortstuff_mt says, the tuner linked by shabaa actually has "dual tuners" for TV (plus an FM radio tuner with its own dedicated input connector). But they way they are set up, one uses one input connector and can ONLY handle analog TV signals which, by now, are available ONLY on cable TV. The other TV tuner with its own input connector can handle all types of digital TV signals, but NOT analog, and only one channel at a time, of course. So you could watch / record two channels at once as long as one is digital (from whatever source) and one is analog from cable.
The alternative tuner shortstuff_mt references arranges things differently. One of its two input connectors is dedicated to the FM tuner, just like the previous tuner card. But the other input connector feeds via an internal splitter into two identical TV tuners. Each of these can handle it all - NTSC analog TV (only from cable), Clear QAM digital TV from cable, and ATSC digital TV from OTA transmitters. So in your case if you hooked one of these to your OTA antenna as TV input, BOTH tuners could tune in different ATSC digital TV channels (HD or not) independently for viewing and / or recording. In your case where your TV signal source is OTA antenna which is ALL ATSC digital signals (unlike cable with some NTSC analog and some Clear QAM digital), this is the kind of "dual tuner" card you need.