Fast method applied to the measurement of microwave power standards

An isothermal method was developed in order to reduce the efficiency measurement time of microwave power standards, using microcalorimeters. The first results given in the two waveguide standards IEC R100, (8.2-12.4) GHz and R220 (18-26.5) GHz show good agreement between classical and isothermal methods. The measurement time has been reduced by a factor of more than three, while keeping the same uncertainties.