New broadband thermal noise primary standard in coaxial technology

摘要

A broadband primary standard for thermal noise measurements is presented and its thermal and electromagnetic behavior is analyzed. It consists of a broadband termination connected to a 3.5mm coaxial airline partially immersed in liquid Nitrogen. The main innovative part of the device is the thermal bead between inner and outer conductors, designed for obtaining a proper thermal contact and to keep low its contribution to the total thermal noise and its reflectivity. A sensitivity analysis is undertaken for establishing the tolerances for proper performance in the range 10MHz–26.5GHz.