In this article, a design of magnetic‐free in‐band full‐duplex (IBFD) RF front‐end with antenna balancing structure is presented. The proposed magnetic‐free IBFD RF front‐end consists of 3 dB hybrid couplers, a Wilkinson power divider, two transmitter (Tx) antennas, and two receiver (Rx) antennas. The proposed IBFD RF front‐end can be implemented and integrated at high frequencies because all the components used in the circuit are non‐magnetic devices. Proposed IBFD RF front‐end eliminated the 3‐dB Tx insertion‐loss of the Balun and transformer in conventional IBFD RF front‐ends using antenna balancing structure. Moreover, there is no noise figure degradation at Rx because it realized only a passive circuit. The mathematical analysis of the cancellation characteristics between two different signals with magnitude and phase difference variations according to the normalized frequencies is presented. Accordingly, the broadband out‐of‐phase balancing power splitter and the antenna balancing structure are adopted to achieve broadband SIC. In order to verify the electrical performances of the proposed magnetic‐free IBFD RF front‐end, it was implemented at the 2.5 GHz WiMax frequency band. When the fabricated IBFD RF front‐end was operated with antenna balancing structure, the measurement results show that the 60 dB SIC bandwidth and maximum SIC were 113 MHz (2.446 ‐ 2.559 GHz) and 75.6 dB, respectively.

中文翻译：

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带天线平衡结构的无磁带内全双工RF前端

本文介绍了一种具有天线平衡结构的无磁带内全双工（IBFD）RF前端设计。拟议的无磁IBFD RF前端包括3 dB混合耦合器，威尔金森功率分配器，两个发射器（Tx）天线和两个接收器（Rx）天线。提议的IBFD RF前端可以在高频下实现和集成，因为电路中使用的所有组件都是非磁性设备。建议的IBFD RF前端使用天线平衡结构消除了传统IBFD RF前端中巴伦和变压器的3 dB Tx插入损耗。此外，由于Rx仅实现了无源电路，因此Rx处的噪声系数没有降低。给出了根据归一化频率幅值和相位差变化的两个不同信号之间的抵消特性的数学分析。因此，采用宽带异相平衡功率分配器和天线平衡结构来实现宽带SIC。为了验证所提议的无磁性IBFD RF前端的电气性能，它是在2.5 GHz WiMax频带上实现的。当所制造的IBFD RF前端采用天线平衡结构工作时，测量结果表明60 dB SIC带宽和最大SIC分别为113 MHz（2.446-2.559 GHz）和75.6 dB。采用宽带异相平衡功率分配器和天线平衡结构实现宽带SIC。为了验证所提议的无磁性IBFD RF前端的电气性能，它是在2.5 GHz WiMax频带上实现的。当所制造的IBFD RF前端采用天线平衡结构工作时，测量结果表明60 dB SIC带宽和最大SIC分别为113 MHz（2.446-2.559 GHz）和75.6 dB。采用宽带异相平衡功率分配器和天线平衡结构实现宽带SIC。为了验证所提议的无磁性IBFD RF前端的电气性能，它是在2.5 GHz WiMax频带上实现的。当所制造的IBFD RF前端采用天线平衡结构工作时，测量结果表明60 dB SIC带宽和最大SIC分别为113 MHz（2.446-2.559 GHz）和75.6 dB。