A primary broad-banded coaxial thermal noise standard for the range 100 MHz to 10 GHz

By means of a new primary coaxial thermal noise standard the realization of the unit watt for noise power has been extended to a broad-banded frequency range from 100 MHz to 10 GHz. The principles of design and construction technologies meet the requirements imposed by theoretical investigations for the heated RF termination and the broad-band matched inner conductor support in the cooled output section. The modular configuration in three well-defined sections has the benefit of a stable temperature distribution over the whole length of the noise standard. Its single structural parts can be machined to a high grade of mechanical precision; their electrical and thermal properties can be measured very accurately. The available noise power is realized by the coaxial thermal noise standard with relative uncertainties of 3.6 · 10⁻³, relating to a confidence level of 0.95.