The six-port measurement technique has played a major role in vector network analysis metrology, particularly within the community of national standards laboratories. Thanks to reduced hardware resource in contrast with conventional and well-established down-mixing heterodyne technique, this paper addresses the six-port technology for amplitude and phase measurements of millimeter-wave signals in the V band. In particular, guided, planar and monolithic IQ six-port demodulators are considered. Advantages and drawbacks of each solution are highlighted to provide a guide to address sensing applications.