The reconfigurable coupler antenna (RCA), also called the flexible coupler antenna (FCA), is a new technique that aims to improve the performance of wireless communication networks by reconfiguring the positions and rotations of low-cost couplers around fixed-position active antennas to harness mutual coupling. Specifically, different couplers can independently adjust their positions and/or rotations at the transceiver to reshape the induced currents on the couplers for radiation, thereby collaboratively achieving mechanical beamforming for directional signal enhancement or nulling. The position and/or rotation reconfiguration of passive couplers provides a new and cost-effective means of enhancing wireless communication performance, while significantly reducing the antenna and radio-frequency (RF) chain costs of conventional active arrays. The compact and low form-factor structure of the RCA makes it particularly appealing for devices with stringent size, weight, and power (SWAP) constraints. In this article, we provide an overview of RCA to reveal its promising capabilities in wireless networks, including its system modeling, practical implementation, and competitive advantages over existing techniques. We present a variety of RCA-enabled performance enhancements in terms of mechanical beamforming gain, path-loss reduction, fading mitigation, spatial multiplexing gain, interference suppression, and geometric gain. Furthermore, we elaborate on the design challenges of RCA as well as promising solutions, and discuss the key applications of RCA in wireless networks. Finally, numerical results are presented to verify the substantial capacity gains enabled by RCA-aided transmission in wireless networks.

翻译：可重构耦合天线（RCA），也称为柔性耦合天线（FCA），是一种旨在通过重新配置固定位置有源天线周围低成本耦合器的位置和旋转方向，利用互耦效应来提升无线通信网络性能的新技术。具体而言，不同耦合器可在收发端独立调整自身位置和/或旋转方向，以重塑耦合器上的感应电流进行辐射，从而协同实现用于定向信号增强或零陷的机械波束赋形。无源耦合器的位置和/或旋转配置提供了一种新颖且经济高效的方法来增强无线通信性能，同时显著降低了传统有源天线阵列的天线和射频（RF）链路成本。RCA紧凑且低外形因子的结构使其特别适用于对尺寸、重量和功率（SWAP）有严格约束的设备。本文概述了RCA，揭示其在无线网络中的潜在能力，包括其系统建模、实际实现以及相对于现有技术的竞争优势。我们展示了RCA在机械波束赋形增益、路径损耗降低、衰落抑制、空间复用增益、干扰抑制和几何增益等方面带来的多种性能提升。此外，我们详细阐述了RCA的设计挑战及有前景的解决方案，并讨论了RCA在无线网络中的关键应用。最后，通过数值结果验证了RCA辅助传输在无线网络中带来的显著容量增益。