On the Response of Multiconductor Superconducting Microstrip Lines Under Plane Wave Excitation

Superconducting microwave circuits are composed of components made from superconducting microstrip transmission lines (SMTLs). The spatial features of the superconductors provide the system operation at high speed and low noise floor. However, coupling the external electromagnetic field in these systems reduces or nullifies their performance. This article presents a general solution for evaluating the electromagnetic behavior of multiconductor SMTLs under plane wave excitation. The analysis is portrayed in the spectral domain. Using the proposed approach, the electromagnetic susceptibility of the lines is evaluated for two proximity SMTLs. It is then investigated in different scenarios where the effect of film thickness, film spacing, and operating temperature is investigated. The study reveals that by increasing the film thickness or film spacing or decreasing the operating temperature, the lines' susceptibility is increased. Further, it is shown that for small film spacing, the susceptibility dependency on temperature or film thickness of one line can affect the susceptibility of the other line.