When radio frequency signals are transmitted via coaxial cable or ribbon cable, the impedance of the cable is significant in determining the load placed on the source and the efficiency of the transmission. Provided the internal impedance of the source and the impedance of the load or termination of the cable are equal, it is possible to manufacture a cable which will present a constant impedance at both ends, regardless of the length of the cable segment. This impedance is called the characteristic impedance of the cable.