A new precision method to measure microwave network parameters is reported in this paper. The reported five-port is developed and simplified from the basic concept of six-port[1

2] but with much simpler and quite defferent design considerations. The ambiguity problem in five-port reflectometer can be avoided via suitable hardware design for any posible value of reflection coefficient （passive or active load）. The design considerations

calibration and some experimental results of a simple five-port reflectometer are presented.