A second generation dual six-port network analyser

A modified dual six-port reflectometry technique is proposed, called biphase-bimodulation. This technique eliminates mechanically precise phase shifters and attenuators used in current designs. Calibration is simple, requiring only five standards in a through-delay-and-match technique. The biphase-bimodulation element consists of a simple directional coupler and two p-i-n diode modulators. The performance of the biphase-bimodulation element is not critical to successful calibration and measurement; its performance is defined during calibration. This reflectometer system promises measurement performance approaching that of heterodyne analyzers with reduced hardware cost and allowing quasi-real-time evaluation of scattering parameters in a swept-frequency measurement system.<>