The invention provides for a method of using a network analyzer and a test controller for measuring S-parameters of a device, which can assume a plurality of states, and which can switch very fast from one state to another. The test controller sends a trigger to the analyzer, which starts a frequency sweep when it receives this trigger. The frequency sweep, having substantially the same start and stop frequency, is provided to the device. The analyzer then executes a measurement of at least one S-parameter of the device, stores the S-parameter data from the measurement and provides the test controller with a trigger. The test controller then updates the device to the next state in a predetermined sequence of states when it receives the trigger from the analyzer. These steps are repeated until all states in the predetermined sequence of states have been measured. In addition, the invention provides for a system for measuring at least one S-parameter of a microwave device, which system comprises a test controller a network analyzer and the microwave device itself.