A novel 2.4 GHz passive duplexer with mismatched load impedance and high isolation between transmitting (TX) and receiving (RX) is proposed for integrated sensing and communication (ISAC) applications. By adjusting the impedance of a canceling tuner located between the quadrature coupler and the antenna, the load impedance of the coupler is tactfully mismatched, which reflects a portion of the TX power with the desired amplitude and phase to cancel out the TX/RX leakage to achieve a high TX/RX isolation of >56 dB. In the meantime, by leveraging the quadrature nature of the quadrature coupler, the proposed duplexer makes it possible for the transceiver to operate at dual circularly polarized (CP) mode, which is beneficial for the polarization requirement of ISAC. The proposed duplexer is fully characterized and evaluated in the custom-designed communication and radar sensing systems, and the simulation and experimental results demonstrate the feasibility for ISAC applications.

中文翻译：

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用于集成传感和通信的具有不匹配负载阻抗的高隔离双工器

提出了一种用于集成传感和通信 (ISAC) 应用的新型 2.4 GHz 无源双工器，该双工器具有不匹配的负载阻抗和发射 (TX) 和接收 (RX) 之间的高隔离度。通过调整位于正交耦合器和天线之间的抵消调谐器的阻抗，耦合器的负载阻抗完全失配，这反映了具有所需幅度和相位的一部分 TX 功率，以抵消 TX/RX 泄漏到实现 >56 dB 的高 TX/RX 隔离。同时，通过利用正交耦合器的正交特性，所提出的双工器使收发器可以在双圆极化（CP）模式下工作，这有利于ISAC的极化要求。