A computationally efficient approach to microwave circuit modeling of complex high temperature superconductor circuits

A computationally efficient approach to modeling complex high temperature superconductor (HTS) microwave circuits is described which combines two-dimensional electromagnetic solutions of microwave transmission lines, incorporating a phenomenological description of HTS behavior, with conventional commercially available microwave-circuit computer-aided-design software. Internal inductance effects are known to have a substantial impact on the design and implementation of narrowband HTS circuits. Phase velocities and characteristic impedances can be well modeled using a phenomenological description of HTS superconductivity along with a generalized approximate boundary condition and a two dimensional electro-magnetic solution to the waveguiding structure. Resultant parameterized design equations can then be incorporated into standard commercially available microwave-circuit computer-aided-design software. The test case examined in detail was the superconducting channelized receiver delivered by the Naval Research Laboratory to Phase II of the High Temperature Superconducting Space Experiment. Excellent agreement was obtained between measurements made on the demultiplexer and this HTS microwave circuit modeling approach.