A calibration method for vector network analyzers using a line and three or more offset-reflect standards

This article proposes a method for two-port vector network analyzer (VNA) calibration that uses a line standard and three or more offset-reflect standards (LnΓ, where n is the number of offset-reflect standards and n ≥ 3). The reflection coefficient of the highly reflecting offset-reflect standards and the propagation constant of the transmission line are unknown for this calibration method, but they can be obtained in the process of calculating the VNA calibration error coefficients. In the LnΓ calibration method, the calibration fixtures are all equal in mechanical length. Therefore, compared with the thru-reflect-line (TRL) method, this calibration method is convenient when the test fixtures of both sides of the VNA are fixed or difficult to move during the measurement. To further simplify the experimental operation, a corrugated reflector is also designed. In this calibration method, only one corrugated reflector used as the offset-reflect standard is needed. Different offset-reflect standards are realized easily by changing the position on the microstrip line. The proposed LnΓ calibration method is accurate, which is proven by theoretical analysis, simulations, and measurements.