Error-Box Calibration of Three-Sampler VNAs

This paper presents measurements of first-tier error-box calibration using a three-sampler architecture of vector network analyzers (VNAs). It is commonly known that error-box calibration is not feasible as a first-tier option for three-sampler VNAs due to the lack of a receiver to measure the switch terms. In a recent paper, we demonstrated the possibility of indirectly measuring switch terms in a three-sampler VNA by using at least three transmissive reciprocal devices without prior calibration. In this paper, we conducted multiline thru-reflect-line (TRL) and short-open-load-reciprocal (SOLR) calibrations using a three-sampler VNA by omitting one receiver in a four-sampler VNA. We evaluated the performance of the calibration by comparing the results when using switch terms calculated directly to the case when switch terms were calculated indirectly. We were able to demonstrate excellent agreement up to 40 GHz. The presented technique can significantly simplify the design of multiport VNAs while still allowing for error-box calibration by using N + 1 samplers instead of 2N samplers, where N represents the number of ports.