Full-duplex (FD) antenna arrays are desirable for expanding the channel capacity of wireless systems up to 2, which is particularly important in the crowded sub-6-GHz spectral bands. Conventional FD solutions based on circulators do not scale to antenna arrays due to the presence of significant mutual coupling between antenna elements. This article describes a two-stage self-interference cancellation (SIC) method that is suitable for FD arrays. The first-stage SIC uses a replica-antenna (RA)-based network that is passive and linear and can thus be placed before the low-noise amplifier (LNA) without significantly degrading receiver noise figure (NF) and linearity. The RA-based SIC also simplifies the hardware requirements for the second-stage SIC, which uses an analog tapped delay line (ATDL) network. The proposed two-stage SIC was realized using off-the-shelf components and tested in the 1–3-GHz range using strongly coupled pairs of ultrawideband antennas. Network analyzer measurements show 20–30 dB of SIC using the RA network over the entire frequency range and >20 dB of SIC using a single-stage ATDL SIC over instantaneous bandwidths of 0.53–0.65 GHz. The combined transmit (Tx)–receive isolation is 66.5, 73.5, and 85.8 dB around the center frequencies of 1, 2, and 3 GHz, respectively. The amount of isolation is shown to be sufficient for realizing practical FD wireless links at 2 GHz with reasonable Tx power levels (0 dBm).

中文翻译：

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用于全双工MIMO无线电的宽带多级自干扰消除器

全双工（FD）天线阵列可用于将无线系统的信道容量扩展到2，这在拥挤的6 GHz以下频谱带中尤为重要。由于天线元件之间存在明显的相互耦合，基于循环器的常规FD解决方案无法扩展到天线阵列。本文介绍了一种适用于FD阵列的两阶段自干扰消除（SIC）方法。第一阶段的SIC使用基于复制天线（RA）的网络，该网络是无源且线性的，因此可以放置在低噪声放大器（LNA）之前，而不会显着降低接收器的噪声系数（NF）和线性度。基于RA的SIC还简化了第二阶段SIC的硬件要求，该阶段使用模拟抽头延迟线（ATDL）网络。拟议的两级SIC是使用现成的组件实现的，并使用超耦合天线的强耦合对在1-3 GHz范围内进行了测试。网络分析仪的测量结果显示，在整个频率范围内，使用RA网络在整个频率范围内的SIC为20–30 dB，而使用单级ATDL SIC的SIC则为> 20 dB的SIC。围绕1、2和3 GHz的中心频率，组合的发射（Tx）-接收隔离分别为66.5、73.5和85.8 dB。隔离程度足以在2 GHz的频率下以合理的Tx功率电平（0 dBm）实现实用的FD无线链路。网络分析仪的测量结果显示，在整个频率范围内，使用RA网络在整个频率范围内的SIC为20–30 dB，而使用单级ATDL SIC的SIC则为> 20 dB的SIC。围绕1、2和3 GHz的中心频率，组合的发射（Tx）-接收隔离分别为66.5、73.5和85.8 dB。隔离程度足以在2 GHz的频率下以合理的Tx功率电平（0 dBm）实现实用的FD无线链路。网络分析仪的测量结果显示，在整个频率范围内，使用RA网络在整个频率范围内的SIC为20–30 dB，而使用单级ATDL SIC的SIC则为> 20 dB的SIC。围绕1、2和3 GHz的中心频率，组合的发射（Tx）-接收隔离分别为66.5、73.5和85.8 dB。隔离程度足以在2 GHz的频率下以合理的Tx功率电平（0 dBm）实现实用的FD无线链路。