Antenna-level Self-Interference Suppression in Full-Duplex Radar via Transmit Beamforming

Journal article, 2026

This letter proposes a transmit beamforming method for antenna-level self-interference (SI) suppression in full-duplex radar. The transmit excitation is constrained to a low-coupling modal subspace derived from the SI coupling matrix while maximizing the received target echo based on an embedded element pattern propagation model. The method is validated experimentally using a coherent radio frequency system-on-chip (RFSoC)–based FMCW radar with closely spaced 3 × 5 Vivaldi transmit and receive arrays. For a 45-dB isolation threshold, the proposed beamformer improves per-element isolation from 30–45 dB to 66–88 dB, provides more than 40 dB suppression across a 100 MHz bandwidth, and recovers target echoes masked under conventional maximum-gain transmission. The results demonstrate that transmit beamforming offers an effective first-stage SI suppression technique for full-duplex radar.