Numerical modeling of superconducting coplanar resonators for radio frequency superconducting quantum interference devices

We have simulated the superconducting coplanar resonators of different designs that we have fabricated and tested as the tank circuit of radio frequency superconducting quantum interference devices. The coplanar resonator is formed by two microstrip lines surrounding a flux concentrator with each line having a slit. The simulated resonant frequencies agreed well with the experimental values, where frequencies decreased with an increasing mutual angular position between the two microstrip slits, and with a short circuit between the two microstrip lines. The simulation also showed that the loss in the system is mainly contributed by the dielectric loss of the substrate materials. (C) 1998 American Institute of Physics. [S0003-6951(98)01942-1].