Full duplex (FD) could potentially double wireless communications capacity by allowing simultaneous transmission and reception on the same frequency channel. A single antenna architecture is proposed here based on a modified rat-race coupler to couple the transmit and receive paths to the antenna while providing a degree of isolation. To allow the self-interference cancellation (SiC) to be maximized, the rat-race coupler was made tuneable. This compensated for both the limited isolation of the rat race and self-interference caused by antenna mismatch. Tuneable operation was achieved by removing the fourth port of the rat race and inserting a variable attenuator and variable phase shifter into the loop. In simulation with a 50 Ω load on the antenna port, better than −65 dB narrowband SiC was achieved over the whole 2.45 GHz industrial, scientific and medical (ISM) band. Inserting the S-parameters of a commercially available sleeve dipole antenna into the simulation, better than −57 dB narrowband SiC could be tuned over the whole band. Practically, better than −58 dB narrowband tuneable SiC was achieved with a practical antenna. When excited with a 20 MHz Wi-Fi signal, −42 dB average SiC could be achieved with the antenna.

全双工 (FD) 通过允许在同一频道上同时发送和接收，可能会使无线通信容量翻倍。此处提出了一种基于改进的老鼠赛跑耦合器的单天线架构，以将发射和接收路径耦合到天线，同时提供一定程度的隔离。为了使自干扰消除 (SiC) 最大化，老鼠赛跑耦合器是可调谐的。这弥补了老鼠赛跑的有限隔离和天线失配引起的自干扰。通过移除老鼠赛跑的第四个端口并将可变衰减器和可变移相器插入环路来实现可调谐操作。在天线端口上具有 50 Ω 负载的仿真中，在整个 2.45 GHz 工业频段上实现了优于 −65 dB 的窄带 SiC，科学和医学（ISM）频段。将商用套筒偶极子天线的 S 参数插入到仿真中，可以在整个频带上调谐优于 -57 dB 的窄带 SiC。实际上，使用实用天线可以实现优于 −58 dB 的窄带可调谐 SiC。当用 20 MHz Wi-Fi 信号激发时，天线可以实现 -42 dB 平均 SiC。