Tracking measurements of a high-power time-varying microwave impedance using three fixed probes

A three-probe system with improved analog signal processing is presented. The system was used to make tracking measurements of the changing complex impedance (or complex reflection coefficient) of a time-varying load operated at power levels from 2.5 to 20 W. A compound load consisting of a magic T, a matched load, a sliding short, and a fixed short was used. The variation of the complex reflection coefficient of this compound load was recorded in real time when the sliding short was moved in and out. The dynamic range of this tracking measurement system covers the range from at least 10 mW to 20 W