As has been suggested you will need an over the air digital TV antenna and an over the air tuner.The antenna connects to that and it connects to your TV with either an AV connection or the now useless analog antenna input of the TV.
An HD tuner will have HDMI and component video outputs so it your TV has those get that rather than a converter box which will only have composite video and RF outputs.
Some will allow for recording and time shifting.
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