Determination of the Phase Center of Sensing Radars Based on Elliptic Phase-Contour Fitting Method

A novel method for determining the phase center of a millimeter-wave short-range sensing radar with sub-wavelength accuracy requirement is presented. Both the antenna structure and transceiver phase-delay effects on the phase center are included. The phase center position is determined based on the measured phase pattern obtained by modulated-transponder rotational scan and analyzed by means of elliptic phase-contour least-square fitting. The modulation on the transponder is used for suppressing the local-oscillator phase noise. The elliptic phase-contour fitting algorithm gives better fitting accuracy. A 24 GHz short-range sensing radar, composed of two 4×4 series-fed patch antenna arrays and a FMCW/CW transceiver chip, is implemented for the experiment. The phase center of this radar is −8 mm (0.64λ o ) along the line perpendicular to the antenna structure axis.