Improvement of primary power standard through international comparison feedback

The high frequency primary power standard is univocally realized by means of a coaxial microcalorimeter, at least up to 40 GHz. The coaxial microcalorimeter is a broadband measurement system adjusted for effec-tive efficiency measurement of power sensors both of bolometric and thermoelectric type. The critical point in the power standard realization is in the determination of the calibration constant g of the microcalorimeter, a frequency dependent parameter that has huge impact on the accuracy as-sessment of the standard. The paper proposes a simple but powerful way for improving this accuracy by using the reference values provided by in-ternational key-comparisons which the microcalorimeter was involved in.