Modeling of Superconductivity for EM Boundary Value Problems
High-temperature superconductivity has spawned a wide search for electronics applications. Various experiments on microwave circuits, including resonators, filters, phase shifters, and small antennas have been performed with promising results. The design of these components will necessarily involve numerical simulation, which requires the solution of superconductive EM boundary value problems. In this paper, several approaches to this solution are presented. In the first approach, superconductors are treated as negative dielectric materials. Secondly, the superconductor surface impedance condition is used at the boundaries. Finally, the problem is solved using perfectly conducting boundaries, and perturbation is used to approximate the desired parameters. The above methods are used to solve the scattering by a superconducting cylinder, propagation in a superconducting parallel-plate waveguide, and radiation by a superconducting short dipole. Very good agreement is found between the negative dielectric model and the surface impedance method. The perfect conductor approximation also gives very good estimates of the fields, but fails to predict some important effects, such as the change in resonant frequency of the dipole with temperature.
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