Compensation of Nonlinearity in Superconducting Transmission Line by Geometrical Restructuring

Superconductors are popular for microwave engineers because they are high performance, high selectivity, and low volume. However, the use of superconductors is limited due to their inherent nonlinearity. Intrinsic nonlinearity in superconductors is due to the dependence of surface current density on the depth of London penetration in them. This leads to adverse effects such as intermodulation distortion (IMD) and the production of a third harmonic in a superconductor. In this article, we intend to improve the effects of nonlinearity by modifying the superconducting geometric structure, which we call the method of geometric reconstruction. To achieve this, we first designed a superconducting transmission line (TL), and then created slots on the superconducting TL to improve the IMD and the third harmonic. Using this method, we managed to reduce the level of the third harmonic from -6 to -31 dBm. To verify the results, after simulating the slotted superconducting TL in ADS software, simulation and solving of London equations using three-dimensional-FEM in COMSOL software has been done again.