Application of a six-port wave-correlator for a very low velocity measurement using the Doppler effect

A new radar system based on a six-port wave-correlator is proposed for measuring the Doppler frequency of a moving object. The six-port wave-correlator is operated as a two-channel wave receiver and the vector relation, both amplitude and phase, between the two input signals is determined directly by measuring the power levels. By using the six-port wave-correlator, no circulator or mixer is needed for the phase measurement. The proposed system has been applied for the measurement of an object moving at a very low velocity. The experiment and simulation results at 10 GHz show that the target velocity around 0.2 mm/s has been successfully inferred, which proved the validity of the proposed scheme.