Reciprocal Full-Duplex FMCW Radar Systems with Self-Interference Cancellation for High Accuracy Distributed Radar Networks

In-Band-Full-Duplex wireless systems are already widely considered in research on communications but also attract increasing interest in radar systems. The latter will significantly benefit from a shared transmit and receive antenna, eg in the process of miniaturization of radar systems for the integration into wearables or for over-the-air network synchronization applications that demand channel reciprocity. However, efficient FMCW full-duplex radars suffer from severe Tx/Rx leakage if no advanced techniques are used. While limited isolation was previously achieved by the use of bulky circulators, there is a high demand for technologies which can be easily integrated into MMICs or on planar PCBs. A viable solution is given by the use of active self-interference cancellation couplers (SICCs). Therefore, this workshop gives an overview of the design and calibration procedure of active SICCs for mm-wave radar systems. With a realized SICC design at 24GHz, we show the achievable isolation and bandwidth and demonstrate its benefits in SFCW radar measurements. Finally, we give an outlook about the benefits of full-duplex-radars for over-the-air synchronization of distributed radar networks.