Equivalent Circuit of a balanced transmission line (such as twin-lead). where: 2/Z = trans-admittance of VCCS (Voltage Controlled Current Source), X = length of transmission line, Z(s) = characteristic impedance, T(s) = propagation function, γ(s) = propagation “constant”, s = jω, j²=-1. Note: Rω, Lω, Gω and Cω may be functions of frequency.