  The field distribution inside the superconducting radiofrequency (SRF) film
with different mean free path is studied using niobium (Nb) as an example. The
surface resistance of clean Nb film with different substrate and different film
thickness is calculated. We also show the study of a special structured
multilayer superconducting film called Superconductor-Insulator-Superconductor
(SIS) structure.
