Simultaneous noise and vector network analysis using radiometer systems

Advances of an original noise measurement approach to simultaneous noise and small-signal characterization of networks are presented. This approach features the use of natural noise for exciting the device under test (DUT) and a radiometer for measuring the response from which the DUT's scattering and noise parameters are then extracted. Different radiometer systems for measurements of one- and two-port devices are considered. They, like a conventional vector network analyzer, need to be calibrated before the measurement. The simplest arrangement, called the multistate radiometer, is a single-channel instrument that measures both the reflection coefficient and the noise temperature of one-port DUTs. Using a pull-source technique, it can be utilized also for a complete characterization of two-port DUTs. Other systems, based on multi-channel radiometers, can perform the same measurements in a more natural way, i.e. by gauging appropriate noise waves at the DUT ports. However, this calls for a more complex instrument design and mathematical model than for the multistate radiometer. The paper presents experimental data showing real capabilities of the multistate radiometer as well as analyses and simulations of the measurement uncertainties achievable with several different multi-channel radiometer systems.