Abstract
In this paper, superconducting transmission lines are analyzed by means of a numerical method which takes into account the experimentally-verified numerical dependence to the magnetic field. In particular, in the framework of the classical electro-dynamics, the high-temperature superconducting material is described by recurring to an enhanced two-fluid model. Striplines and microstrip lines are considered and the attenuation constants of these guiding structures are computed by assuming quadratic and cubic nonlinearities.