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.<>