Silicon technologies are now widely used for radio frequencies applications. Due to the substrate and conductor conductivity, losses and magnetic coupling affect the signal propagation in transmission line. We propose an equivalent scheme for a transmission line taking these phenomena into account. All the parameters are analytically extracted from measurements. The magnetic coupling, including eddy currents, are described as series elements. They are affected by skin effect. The electric losses are described as parallel elements. They depend on the different layers that the electric field lines meet.