Due to power attenuation, improving transmission efficiency in the radio-frequency (RF) band remains a significant challenge, which hinders advancements in various fields of the Internet of Things (IoT), such as wireless power transfer (WPT) and wireless communication. Array design and retro-directive beamforming (RD-BF) techniques offer simple and effective ways to enhance transmission efficiency. However, when the target is an array or in the near field, the RD-BF system (RD-BFS) cannot radiate more energy to the target due to phase irregularities in the target region, resulting in challenges in achieving higher efficiency. To address this issue, we propose the RF-based resonant beam system (RF-RBS), which adaptively optimizes phase and power distribution between transmitting and receiving arrays by leveraging the resonance mechanism to achieve higher transmission efficiency. We analyze the system structure and develop an analytical model to evaluate power flow and resonance establishment. Numerical analysis demonstrates that the proposed RF-RBS achieves self-alignment without beam control and provides higher transmission efficiency compared to RD-BFS, with improvements of up to 16%. This self-alignment capability allows the system to effectively transfer power and information across varying distances and offsets. The numerical results indicate the capability to transmit watt-level power and achieve 21 bps/Hz of downlink spectral efficiency in indoor settings, highlighting the advantages of RF-RBS in information and power transfer for mobile applications.

翻译：由于功率衰减，提升射频波段的传输效率仍是一项重大挑战，这阻碍了物联网（IoT）各领域的进展，例如无线能量传输（WPT）和无线通信。阵列设计与逆向波束赋形（RD-BF）技术为提升传输效率提供了简单有效的方法。然而，当目标为阵列或处于近场区域时，由于目标区域的相位不规则性，RD-BF系统（RD-BFS）无法向目标辐射更多能量，导致实现更高效率面临挑战。为解决此问题，我们提出基于射频的谐振波束系统（RF-RBS），该系统利用谐振机制自适应地优化发射与接收阵列间的相位与功率分布，以实现更高的传输效率。我们分析了系统结构，并建立了一个分析模型以评估功率流与谐振建立过程。数值分析表明，所提出的RF-RBS无需波束控制即可实现自对准，且相较于RD-BFS能提供更高的传输效率，提升幅度最高可达16%。这种自对准能力使系统能够在不同距离和偏移条件下有效传输能量与信息。数值结果表明，该系统在室内环境下能够传输瓦级功率，并实现21 bps/Hz的下行链路频谱效率，凸显了RF-RBS在移动应用信息与能量传输中的优势。