A measurement system and method for conducting measurements on a device-under-test (DUT). The system includes, in one embodiment, a passive impedance controlling tuner, and a signal transmission line, the tuner including a signal transmission line segment as at least part of the signal transmission line. A signal coupling device is coupled in a non-contacting relationship to the signal transmission line between a signal port of the DUT and the tuner for sampling signals propagating between the passive impedance controlling tuner and the DUT to allow measurement of an actual impedance presented to the DUT with the DUT in place in the measurement system during measurement of DUT characteristics. Measurement system equipment receives response signals from the signal coupler. The measurement system is configured to conduct measurement of DUT characteristics without pre-characterizing the impedance controlling tuner.