New calibration method for coaxial microcalorimeters

The most critical point in the realization of an electrical power standard based on a microcalorimeter is the accurate determination of the microcalorimeter losses and their effect on the measurand, i.e., the effective efficiency of the sensor under calibration. At the Istituto Elettrotecnico Nazionale (IEN) Galileo Ferraris, a procedure has been introduced that makes the microcalorimeter constant determination more accurate and reliable. Experiments with the 7-mm coaxial microcalorimeter in 50 MHz-18 GHz range have shown a significant improvement in the uncertainty for the Italian national power standard at the 0.2% level.