Thermoelectric Sensors as Microcalorimeter Load

Thermoelectric power sensors, instead of bolometers, can now be used as transfer standards in the microcalorimeter technique. This alternative has the technical advantages of being less sensitive to absolute temperature and not downward frequency limited. At the Istituto Nazionale di Ricerca Metrologica, the high-frequency power standards are based on coaxial thermocouples that operate in the frequency range that spans from direct current to 34 GHz. Modified commercial thermocouple mounts in the 7- and 3.5-mm coaxial lines are used to realize the national power standard with an accuracy ranging from 0.03% to 1% in the aforementioned frequency range.