A systematic analysis of measurement uncertainties in rectangular waveguide calibrations is condcuted. Uncertainty budgets for different waveguide bands are examined, individual uncertainty contributions are discussed and the significant impact of connection repeatability is highlighted. Consequently, an investigation into misaligned waveguide interfaces is undertaken, emphasizing the importance of precise alignment, supported by simulation and experimental data.

In this study, the impact of LO signal variations on VNA measurements is investigated. The effect of LO signal changes is studied through theoretical analysis and experiments. It is found that even minor LO signal phase changes after calibration significantly affect the measured phase angles of transmission coefficients. Error correction terms are derived and applied to correct errors in the experimental data. The results shows that corrected measurements remain unaffected by the effect.