Modeling the series impedance of a quad cable for common mode DSL-applications

Digital Subscriber Line technology provides broadband services over the twisted pair copper wires of the existing telephone network. Current DSL systems make only use of differential mode signals. In next generation DSL technologies, the common mode signal will also be exploited. This will lead to much faster technologies. New transmission line models, which take also the common mode signal into account, have to be set up. The derivation of the models is based on the multiconductor transmission lines theory. A binder with twisted pairs can be represented by an electric scheme which contains a resistor R and an inductance L for each wire and a capacitance C and a conductance G between each two wires. The series impedance gives good approximations for the R and L value. This impedance is modeled and validated with measurements.