A new microcalorimeter for measurements in 3.5-mm coaxial line

A new microcalorimeter has been realized for implementing the national power standard up to 26.5 GHz in a 3.5-mm coaxial line at the Istituto Elettrotecnico Nazionale (IEN) Galileo Ferraris, Turin, Italy. The system is based on a dry thermostatic cell controlled by Peltier elements. The thermal load consists of a twin sensor system that is alternately supplied with high frequency test power and low frequency or direct current (DC) reference power through adiabatic coaxial lines. This microcalorimeter was originally designed for calibrating bolometric mounts. Recently, it has been modified for thermocouple power sensors, which can operate from DC to 26.5 GHz in a 3.5-mm coaxial line.