Vector mixer characterization for image mixers

The vector mixer characterization method first introduced by Dunsmore can be used only for mixers where the local oscillator (LO) frequency lies between the RF input and output frequencies. Attempts to use the method for image mixers, where the LO is greater than both the input and output frequencies, yield erroneous results. An improved method is described which can properly characterize both type of mixers. A theoretical basis is introduced and experimental results presented which justify the new method.