TV Antenna, HDTV 4K HD Digital TV Antenna with Amplifier Signal Booster Free Local Channels  to avoid interference If the antenna feeder is too long, or redundant feeders are bundled together, it is easy to duplicate the picture. Therefore, the feeder length shall be shortened as far as possible without affecting the antenna height. It is better to rotate the antenna feeder to prevent external interference, and align the angle direction with the TV station or weak signal station to improve the reception effect