Telecommunications cables are a type of guided transmission mediums. Cables are usually known to transmit electric energy (AC/DC); however, cables in telecommunications fields are used to transmit electromagnetic waves; they are called electromagnetic wave guides. Telecommunications are based on transmitting modulated waves/signals through a medium and receiving them. When the distance between the transmitter and receiver is far, or an unguided medium transmission is used, antennas are used; otherwise, telecommunications cables are used in guided medium transmission.