The design and implementation of a full-duplex radio system capable of real-time analogue self-interference cancellation at radio frequency (RF) and baseband stages are presented. The system consists of a dual-patch three-port orthogonally linear polarised antenna system (without a circulator/duplexer), a homodyne dual receiver, and a differential amplifier at the baseband. The interference outputs from the two receivers are equalised using a fixed attenuator and when they are passed through the differential amplifier at the baseband they are effectively cancelled. For the system reported the antenna system provides 45.1 dB isolation between transmit and receive ports over 60 MHz bandwidth centred at the operating frequency of 3.2 GHz. Interference cancellation achieved by the differential amplifier at the baseband reduces the total self-interference to 81.5 dB minimum at −5.6 dBm transmit power. Using the proposed system, the recovery of two different types of baseband signals in real time is demonstrated while the surrounding is multipath enabled. Since the self-interference at baseband is removed by the differential amplifier instead of a complex digital signal processing unit, it makes the proposed system suitable for broad-band millimetre-wave full-duplex transceivers where the use of analogue/digital converter is not an option.

中文翻译：

---

具有两个接收器的全双工无线电，用于自干扰消除

提出了一种能够在射频（RF）和基带级进行实时模拟自干扰消除的全双工无线电系统的设计和实现。该系统由一个双跳三端口正交线性极化天线系统（没有环行器/双工器），一个零差双接收机和一个基带差分放大器组成。来自两个接收器的干扰输出使用固定衰减器进行均衡，当它们在基带通过差分放大器时，可以有效地消除它们。对于所报告的系统，天线系统在60 MHz带宽（中心频率为3.2 GHz）上的发送端口和接收端口之间提供45.1 dB的隔离。在−5.6 dBm的发射功率下，差分放大器在基带处实现的干扰消除将总自干扰降至最低81.5 dB。使用提出的系统，演示了实时恢复两种不同类型的基带信号，同时启用了多路径环境。由于基带的自干扰是由差分放大器而不是复杂的数字信号处理单元消除的，因此，该系统适用于宽带毫米波全双工收发器，在这种情况下，模/数转换器的使用并不适用。选项。