Experimental characterization process of DC-offset performance for Multiple CW Doppler Radar

Continuous-wave (CW) Doppler radar with a quadrature direct-conversion receiver (DCR) has critical issues about Direct-current (DC) offset to manage and measure it when remotely monitoring vital signs which are closely resemble DC values. The characterization process using Radio frequency (RF) single tone has been carried out to measure DC offset, but there is no known method for supporting multiple CW. This paper categorizes DC offset as one of a system DC offset and an environment DC offset, and proposes 1 to 5 experiments of a DC offset characterization process supporting multiple CW. The result experimentally shows that DC offsets have the tendency to follow experiment 4 of characterization when the RF-to-local oscillator (LO) isolation is achieved by using the absorber in front of the antenna.