Pinching-antenna systems have recently emerged as a promising solution for enhancing coverage in high-frequency wireless communications by guiding signals through dielectric waveguides and radiating them via position-adjustable antennas. However, their practical deployment is fundamentally constrained by waveguide attenuation and line-installation requirements, which limit the achievable coverage range. To address this challenge, this paper investigates a wireless-fed pinching-antenna architecture that employs highly directional horn antennas to enable efficient coverage extension. Specifically, a full-duplex amplify-and-forward relay equipped with horn antennas is introduced between the base station and the waveguide input, which significantly improves the link budget in high-frequency bands while effectively eliminating self-interference. On this basis, we formulate a total power minimization problem subject to a quality-of-service constraint at the user equipment, involving the joint optimization of the pinching-antenna position, the relay amplification gain, and the base station transmit power. By exploiting the structure of the end-to-end signal-to-noise ratio, the optimal pinching-antenna position is first obtained in closed form by balancing waveguide attenuation and free-space path loss. Subsequently, closed-form expressions for the optimal relay gain and transmit power are derived. Numerical results demonstrate that the proposed scheme substantially outperforms conventional systems without relaying and relay-assisted transmission with fixed antennas in terms of total power consumption.

翻译：夹持天线系统作为一种新兴解决方案，通过介质波导引导信号并经由位置可调天线辐射，为提升高频无线通信的覆盖性能提供了有效途径。然而，波导衰减与线路布设需求从根本上制约了该系统的实际部署，限制了其可实现的覆盖范围。为应对这一挑战，本文研究了一种采用高定向性喇叭天线的无线馈电式夹持天线架构，以实现高效的覆盖扩展。具体而言，在基站与波导输入端之间引入配备喇叭天线的全双工放大转发中继，该设计在显著改善高频段链路预算的同时，有效消除了自干扰。在此基础上，我们构建了在用户设备服务质量约束下的总功率最小化问题，涉及夹持天线位置、中继放大增益与基站发射功率的联合优化。通过利用端到端信噪比的结构特性，首先通过平衡波导衰减与自由空间路径损耗，以闭式解形式获得了最优夹持天线位置。随后，推导出最优中继增益与发射功率的闭式表达式。数值结果表明，所提方案在总功耗方面显著优于无中继的传统系统以及采用固定天线的中继辅助传输方案。