In 1973, a six-port network analyzer was developed. It uses a single six-port network consisting of a directional coupler and a hybrid connector (magic T) as the measurement unit. Except two ports are connected to the signal source and the measured component respectively, the other four ports are connected to an amplitude detector or a power meter. The modes and phases of the scattering parameters of the measured network can be obtained by proper combination of the detected four amplitudes. It does not need to use complex dual channel receivers to obtain phase information, thus greatly simplifying the hardware of the measurement system. In addition, it has more than the necessary number of redundant measurement ports, which can be used to check each other between redundant data to improve the reliability of measurement results. But its calculation is much more complicated than that of four-port network analyzer. Dual-six-port network analyzer is used to measure dual-port network, i.e. a single six-port network analyzer is connected to port 1 of the network under test and port 2 of the network under test, which can avoid switching or manual inversion of the input and output terminals of the network under test in the measurement process, and further improve the accuracy of measurement.