A Ka-band FMCW radar front-end with adaptive leakage cancellation

Monostatic frequency modulation continuous wave radars that use one antenna to simultaneously transmit and receive can result in compact and lightweight synthetic aperture radar systems. One of the greatest challenges in designing a continuous-wave monostatic radar is realizing enough isolation between the transmitter and the receiver. A novel real-time digital signal processing scheme is proposed to cancel the transmitter leakage at the receiver front-end and to achieve high isolation. With the digital implementation, the proposed scheme shows a much more precise control of the leakage cancellation when compared to conventional analog implementations. The de-offset problem in analog mixers that affects the cancellation performance is eliminated. A radar test bed at 26 GHz has been built and tested in several radar modes. The measurement shows a leakage suppression of more than 30 dB over a 1.7-GHz sweeping bandwidth.