Polarforming is a promising technique that enables dynamic adjustment of antenna polarization to mitigate depolarization effects commonly encountered during electromagnetic (EM) wave propagation. In this letter, we investigate the polarforming design for secure wireless communication systems, where the base station (BS) is equipped with polarization-reconfigurable antennas (PRAs) and can flexibly adjust the antenna polarization to transmit confidential information to a legitimate user in the presence of an eavesdropper. To maximize the achievable secrecy rate, we propose an efficient iterative algorithm to jointly optimize transmit beamforming and polarforming, where beamforming exploits spatial degrees of freedom (DoFs) to steer the transmit beam toward the user, while polarforming leverages polarization DoFs to align the polarization state of the EM wave received by the user with that of its antenna. Simulation results demonstrate that, compared to conventional fixed-polarization antenna (FPA) systems, polarforming can fully exploit the DoFs in antenna polarization optimization to significantly enhance the security performance of wireless communication systems.

翻译：极化赋形是一种通过动态调整天线极化以缓解电磁波传播过程中常见去极化效应的前沿技术。本文研究了面向安全无线通信系统的极化赋形设计，其中基站配备极化可重构天线，能够在窃听者存在的情况下灵活调整天线极化状态，向合法用户传输机密信息。为最大化可达保密速率，我们提出一种高效的迭代算法，联合优化发射波束赋形与极化赋形：波束赋形利用空间自由度将发射波束导向目标用户，而极化赋形则借助极化自由度使到达用户端的电磁波极化状态与其天线极化相匹配。仿真结果表明，相较于传统固定极化天线系统，极化赋形能够充分利用天线极化优化的自由度，显著提升无线通信系统的安全性能。