Attaining low uncertainties in measurements with RF signal generators and analyzers

In this paper, practical investigations of level accuracy and uncertainties using a Rohde & Schwarz signal generator (R&S SMB-B140) and spectrum analyzer (R&S FSV40) are performed up to 30GHz. We show that it is possible to measure frequency responses of DUTs with uncertainties below ±0.05dB up to 30 GHz instead of ±0.5…1.5dB using auto settings, standard setup, or relying on datasheets. The level linearity of instruments with integrated step attenuators is shown to be improved to ±0.03dB instead of ±0.3…1dB by using a special “hybrid” procedure. Furthermore, it is shown how computer aided measurements procedures should be programmed with these instruments to attain low deviations between measurements.