An Ultra-Wideband High-Isolation Single-Antenna Full-Duplexer Based on Dual-Phase Cancellation

Wideband transmit–receive shared-antenna full-duplexers are a key technology for radar, communication, and electronic countermeasure systems. In special scenarios such as retrodirective cross-eye jamming, RF systems must adopt a TR shared-antenna architecture with a frequency coverage of 6–18 GHz. However, high-power signals leaking from the transmitter in this architecture interfere with the reception of useful signals at the receiver. To address this issue, this paper proposes an ultra-wideband high-isolation anti-symmetric duplexer. This duplexer is configured with one 180° hybrid coupler, one power divider, and two circulators. Based on a dual-phase cancellation mechanism, it theoretically enables complete suppression of self-interference signals induced by circulator leakage and antenna standing waves. Experimental results demonstrate that the proposed duplexer achieves Tx–Rx isolation exceeding 33 dB over the 6–18 GHz band. Compared with traditional duplex systems based on a single circulator and an orthogonal balanced network, the proposed design improves isolation by 13–22 dB. This work represents the first passive full-duplexer architecture to simultaneously cancel both circulator leakage and antenna reflections over the full 6–18 GHz band. This scheme can be extended to applications in retrodirective cross-eye jammers as well as other radio-frequency systems that face wideband isolation problems. Keywords: Transmit-receive isolation, full-duplexer, ultra-wideband, retrodirective cross-eye jamming