If your cable TV provider supplies FM radio stations, you can pick up the signal through a cable connected to your home theater or stereo receiver. Some receivers are equipped with a coaxial input to connect with a cable. Other models have a pair of spring-clip connectors that hold the two wires for an FM antenna. For a wire connection, you'll need a device called a Balun transformer, which has two wire leads on one end and a coaxial jack on the other. A Balun transformer can also be used to connect a wire-lead receiver to a coaxial cable antenna for improved reception.
Turn off and unplug the receiver.
Connect the coaxial cable directly to the receiver's matching input jack or hook up the cable to the coaxial jack on one end of a Balun transformer. Twist the metal fastener on the cable end clockwise around the jack.
Attach the two wires on the other end of the transformer to the two terminals on the receiver labeled for an FM antenna. Either wire can be hooked up to either antenna terminal for this type of connection.
Connect the other end of the cable to the output jack on the back of the cable box or to the jack on the base of your antenna.