Adaptive leakage cancelation method in frequency modulated continuous wave radar for foreign object debris detection

Frequency modulated continuous wave (FMCW) radar is widely used for foreign object debris (FOD) detection. A major defect of FMCW radar is that the unpreventable phase noise of the transmitter will bring leakage signal to the receiver, leading to a severe degradation of detection sensitivity for FOD. In this work, we first analyzed the radar output signal and explored the time‐domain characteristics of the leakage signal. Based on this, we proposed a novel adaptive leakage cancelation method that can eliminate the leakage signal in the intermediate frequency domain. The proposed method only needs digital signal processing without additional hardware. Furthermore, this method can track the change of leakage signal adaptively to keep radar's high detection accuracy all the time. An experiment that using a 76 GHz FMCW radar has been carried out to verify the effectiveness of our method. The results showed that the leakage signal calculated by this method has a 99% correlation coefficient with the actual leakage signal. The system noise floor is significantly decreased after the cancelation, and the suppression of DC component which caused by leakage is more than 60 dB, all of those showed that our method achieves almost perfect cancelation of the leakage.