  In the paper, a comparison is described of the microwave power standard based
on thermoelectric sensors against an analogous standard based on bolometric
sensors. Measurements have been carried out with the classical twin-type
microcalorimeter, fitted with N-connector test ports suitable for the frequency
band 0.05 - 18 GHz. An appropriate measurand definition is given for being
suitable to both standard types. A system accuracy assessment is performed
applying the Gaussian error propagation through the mathematical models that
interpret the microcalorimeter response in each case. The results highlight
advantages and weaknesses of each power standard type.
