The Six-Port Technique: A Brief Review

The 's' parameters of microwave devices have been satisfactorily measured by the usual network analyzer for the last few decades. The principle of its operation requires a complex circuitry which has to convert tihe reference and test signals to an intermediate frequency while keeping the same phase and amplitude relation between them. This makes the equipment very complex and expensive especially at millimeter wavelengths. A cheaper and practical alternative for the network analyzer was introduced by Glenn Engen and Cletus Hoer in the 70's at the National Bureau of Standard, Colorado.