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 effective 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 assessment of the standard. The paper proposes a simple but powerful way for improving this accuracy by using the reference values provided by international key-comparisons which the microcalorimeter was involved in.