Direct calculation of attenuation and propagation constants in superconducting microwave structures

The authors present a complete model which can be used for any of the transmission line structures which include high-T/sub c/ superconducting material. This model incorporates all the physical aspects of the high-T/sub c/ superconductor materials through London's equations. It also satisfies all the electromagnetically required boundary conditions in the structure using Maxwell's equations. The physical characteristics of the superconductor are blended with the electromagnetic model by using the phenomenological two-fluid model. The finite difference method is used to implement this model because it has a great deal of flexibility, and equations may be derived directly from Maxwell's equations. The complex propagation constant is calculated. The losses inside the superconductor material are also evaluated. Numerical results are generated for two configurations, a superconductor microstripline filled with a lossless dielectric material with /spl epsi//sub d/=23 or with air.<>