Adjustable Complex-Ratio Transformer

A four-terminal network in which the complex output-to-input ac current or voltage ratio may be adjusted is described. The design of an experimental Adjustable Complex-Ratio Transformer for use at a frequency of 60 Hz, in which the output-to-input current ratio (Io/Ii = ??+j??) can be adjusted with two sets of 5 decade dials to 0.1 percent accuracy, is presented. The application of the instrument for the direct reading of the difference of two alternating currents is discussed.