Spectral Purity Measurement of Millimeter-Wave Signal Sources

This paper introduces a spectral purity issue on millimeter-wave signal sources, which are indispensable to millimeter power standard systems and general millimeter-wave measurement setups. We briefly describe the difficulties in analyzing the results of conventional spectral purity measurement with an external mixer. A newly available external mixer-free measurement setup is shown with data. This setup allows the measurement to be free from multiple intermodulation and conversion gain (loss) compensation to 110 GHz. The spectra of V-band signal sources, which have a different multiplying number, are compared, and the effects of the number on the spectrum are discussed.