A system equation of a recently developed null-balanced, tulal-pcnver radknnclcr system h rigorously derived. Delivered noise ptpwer and temperature is related to available power (temperature) through an extcnskin uf (he mismatch factor to broadband systems. The available power ratio a,, the available gain G^ and the delivered power ratio (efficictjcy) jji are defined. Properties of idealized, but in principle realizable components such as an infinitely directive isolator and a lossless matched wavcguide-below-cutoff attenuator are used. A cascading technique is repeatedly applied to the fundamental noise equation. Mathematically modeling the experimental pmcedure of seijucntially attaching the two noise standards and the unknown source to the system input, we obtain the system of three equations that can be solved for the noise temperature of the unknown noise source. K^ ifMds: broadband; calibratioo; noise power, noise temperature; nullbajanccd; ^tem equation; total power radiometer section.
Accepted: October 12, J993
A receniiy developed radifimeter system NCSt is used to calibrate thermal noise tenipcramrc at any frei|uency tictwccn 1,0 GHz and 12.0 GHz, Any cryogenic noise source can be measured; the upper limit n{ noise temperatures measured without a loss of accuracy is estimated to be ahtiut 10^ K. For a typical hot noise source with the noise temperature of 8400 K and a reflection eocfCicient magnitude of 0.1, the expanded uncertainty is » 1.6%, and the system sensitivity ^Z K. Implemented in Type N connector, it can be ea
Uncertainties of the NIST broadband coaxial calibration system are analyzed. The expanded relative uncertainty for a source with the ENR of M 15 dB is typically 1.6 %.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.