Towards a Full-Duplex CW Radar: Development of a Reflected Power Canceller in Digital Domain

This paper deals with the challenges of transmitter-receiver isolation in Continuous-Wave Radars. Based on a Full-Duplex configuration, the leakage power from typical modern radar components has been measured. The aim of this study is the suppression of this self-interference in the digital domain. For this purpose, a deep analysis of the transfer functions and impulse responses of the radar components has been performed. Under the assumption of stationarity, the Wiener Filter Model was applied to obtain an optimal description of the system, from which the main filter coefficients were identified. The investigation was then enhanced for non-stationary systems. Leading to an advanced self-adaptive digital canceller which uses a minimum number of coefficients for the LMS-parameter learning and a Gram-Schmidt orthonormalization stage. The proposed digital solution achieves a cancellation of the self-interference down to the receiver noise floor of the test system.