A W-Band Network Analyser System using up-Conversion

A complex S-parameter measurement system in the 94 GHz region essentially needs a sweep signal generator, e.g. in the range 91 GHz through 97 GHz. Several approaches are possible: an unstabilized IMPATT sweeper, which must generate sufficiently small noise to enable source locking in the network analyzer (Ref. l, 2); a synthesizer, which fulfills this requirement inherently by design, but at higher cost; and at last, as outlined here, a conventional sweeper at much lower frequencies. The sweeper provides a direct drive signal to the network analyzer´s reference signal input as well as to an upconverter´s low frequency input (IF port), which generates at its RF port the desired W-band sweep signal. In this manner, source locking reveals no problem and, as the test signal downconverter uses the same local oscillator as the upconverter, the network analyzer´s test signal input is driven coherently to the reference signal input.