An Active Self-Interference Cancellation Front-end for Stepped-Frequency Continuous-Wave Radar

This work presents the development of a Stepped- Frequency Continuous Wave (SFCW) radar with active self-interference cancellation (SIC), for the UHF band up to 3 GHz. The radar is monostatic with separate Transmission (TX) and Receiving (RX) antennas, with passive cancellation through isolation between the TX and RX antennas. The active cancellation is done with an RF modulator that generates a cancelling signal in phase opposition to the self-interference (SI), reducing its impact in the target detection. By using two independent local oscillators, the receiver architecture is configurable for homodyne or heterodyne. With the prototype, a passive antenna isolation of approximately 30 dB and a SIC of 17 dB, through the adjustment of the cancelling signal’s amplitude and phase, were demonstrated, for a total cancelling of 47 dB.