Microwave Transmission Properties of Coaxial Cables at Low Temperatures

Probing solids, e.g. superconductors, at low temperatures using microwave spectroscopy is a powerful approach to understand unconventional electronic states. Such cryogenic microwave experiments are challenging, and one important aspect is the strong temperature and frequency dependence of the transmission properties of the microwave coaxial cables that are employed.

Goal of this project is to measure the microwave transmission (amplitude and phase) of different coaxial cables in wide ranges of frequency (100 MHz to 20 GHz) and temperature (1.6 K to 300 K). On a fundamental level, we want to understand how these transmission properties depend on the material properties of the coaxial cables (e.g. whether the conducting parts are made of poor, good, or superconducting metals and whether there are additional coatings). Considering cryogenic microwave applications, we want to determine the relevant cable parameters that have to be considered when designing such experiments.

Keywords: Microwaves, Microwave Spectroscopy, Low Temperatures