Prospective study of the influence of superconducting strips in various coplanar waveguides is proposed using a transmission line model designed in an engineering purpose for CAD programs. This model is tested using a comparison of the results obtained, with the propagation characteristics of superconducting coplanar lines determined with a modified spectral domain approach. For insulating coplanar waveguides the use of YBaCuO instead of classical low temperature NbN superconductor provides lower losses at higher operating temperatures. In superconducting MIS or Schottky contact lines, superconductor losses are negligible as compared to semiconductor losses for transverse dimensions as low as 1 μ. For example, 1 μ gate length FET type structures operated at 77 K exhibit 50 Ω constant characteristic impedance with associated constant slowing factor, and losses lower than 4 dB/mm up to 20 GHz. Similar propagation characteristics can be obtained with different superconductors providing that current transport in superconductor is dominated by the kinetic inductance effect. The influence of temperature is also discussed.