Phenomenological loss equivalence method for planar quasi-TEM transmission lines with a thin normal conductor or superconductor

The incremental inductance rule for conductor loss calculations is not valid if conductor thickness decreases and becomes comparable to the penetration depth. A simple approach, referred to as the phenomenological loss equivalence method is proposed for characterizing a planar quasi-TEM transmission line with a thin normal conductor or superconductor over a wide range of field penetrations. For microstrip lines with a thin copper or high-T_c superconductor, the conductor losses calculated by this method agree very well with the published data calculated by the finite-element method and the Monte Carlo method, respectively. Because of the simplicity of the calculation, the method should be very useful for the computer-aided design of monolithic microwave circuits