The influence of load standard on VNA single port measurement accuracy

Vector Network Analyzer is a type of widely used microwave measurement instrument. It can achieve high measurement accuracy for its calibration function. In Calibration, the instrument measures a series of calibration standards of which characteristics are known to quantify the error items of the instrument. The error will be corrected during measurement. The measurement accuracy is related to the accuracy of the calibration standards. Calibration standards will cause error for they are not perfect. Load standard is different from ideal match, so it is one of the most important factor to influence measurement accuracy. In this paper, the author illustrated the principle of single-port network measurement, and introduced error sources and calibration model. Then the author analyzed and calculated the measurement error when using fixed load standard. Afterward, the measurement error caused by slide load standard was analyzed. In the end, other factors affect measurement accuracy were pointed out.