All broadcast television stations in the United States are required by law to broadcast over-the-air signals in digital format only. This enables you to receive free high-definition channels with Comcast or any other cable provider because you receive them over the air rather than through a cable subscription. In addition to HD channels, stations can broadcast multiple shows simultaneously on the same channel. As a result, you might have three channel 7's, indicated by 7-1, 7-2 and 7-3.
Purchase an antenna if you don't already have one for your television. Make sure the antenna can receive UHF and VHF channels. Refer to the FCC's guide on antennas and digital TV for more advice on selecting the right antenna for your television (link in Resources).
Visit the FCC-endorsed AntennaWeb site published by the Consumer Electronics Association and the National Association of Broadcasters (link in Resources). Choose "Click Here to Start," enter your zip code and street address and choose "Submit." Review the resulting list of stations you can receive and the best direction to point the antenna to receive the stations.
Determine the channels you want to receive, and point your antenna accordingly. Switch the television to an alternate input, and select "Over the Air" or a similar option to view broadcast TV stations. Select the option to scan available channels, and wait while the television seeks out the free HD channels you can pick up at home.