A Novel Calibration Method for Active Interferometer-Based VNAs

The addition of RF interferometers to vector network analyzer (VNA) test benches has allowed for realization of low-noise high-frequency measurements of extreme impedance devices. However, when employing correction techniques such as the short-open-load method, the RF response of the interferometer hardware introduces measurement inaccuracies due to unwanted load-dependent inconsistencies. This letter presents a novel VNA calibration method that enables both low-noise and accurate small-signal characterization of highly mismatched devices. The proposed solution is experimentally validated in the 10-18-GHz band, confirming a 23-fold improvement in measurement resolution with absolute accuracy across the entire $\Gamma $ range of the VNA. The accuracy of the new calibration process is verified via comparison with traceable reference standards supported by state-of-the-art uncertainties.