A TV antenna amplifier adds energy to input signals from the TV station broadcast towers the antenna picks up. This strengthens the signals, which can improve the picture and sound quality of those stations on the user's TV.
The effectiveness of TV antenna amplifiers varies based on the amplifier and the user's location. For weak signals, due to the antenna's distance from the broadcast tower or obstructions between the antenna and the tower, amplifiers often improve the station's picture and sound quality. However, amplifiers sometimes have negative effects on quality when there are strong signals in the area. Amplifying these signals overloads the TV tuner, resulting in lower quality for stations with weak and strong signals. Because of this, amplifiers tend to work more effectively in areas far from broadcast towers, as opposed to city locations with broadcast towers nearby.
Since the amplifier only amplifies and doesn't correct signals, it provides no benefit with distorted signals, as they become stronger but remain distorted. An amplifier is only able to amplify signals in the area, it doesn't create or obtain new signals.
Amplifiers work well with TV antennas that are outdoors or in attics. The cable length from the antenna to any TVs weakens the signal, but an amplifier corrects this issue.