This letter investigates the integration of pinching-antenna systems (PASS) with orthogonal frequency division multiplexing (OFDM) to ensure their compatibility and to explore the frequency-selective behavior inherent to PASS. First, an end-to-end channel model for OFDM PASS is proposed based on electromagnetic-compliant modeling of waveguides and coupled-mode theory, which includes frequency-dependent waveguide attenuation, dispersion and antenna coupling effect. Furthermore, a critical dependence of the OFDM cyclic prefix (CP) overhead on the proximity of the operating frequency to the waveguide cutoff is revealed. Moreover, the phase misalignment effect across subcarriers in OFDM PASS is derived for an approximate pinching antenna location strategy based on path loss minimization, which reveals the phase misalignment is exacerbated for wider bandwidths and larger array size. Numerical results show that: 1) frequency-selective effects in OFDM PASS lead to substantial variations in subcarrier achievable rates, highlighting the necessity of operating above the waveguide cutoff frequency for effective communications; 2) waveguide dispersion mandates considerable CP overhead when operating near the cutoff frequency, severely impacting the spectral efficiency of OFDM PASS; and 3) the gentle linear waveguide attenuation in a practical PASS significantly more advantageous than the severe logarithmic path loss characteristic of fixed-location antennas.

翻译：本文研究了夹持天线系统与正交频分复用技术的集成，以确保其兼容性并探索夹持天线系统固有的频率选择性行为。首先，基于波导的电磁兼容建模和耦合模理论，提出了OFDM夹持天线系统的端到端信道模型，该模型包含了频率相关的波导衰减、色散和天线耦合效应。此外，揭示了OFDM循环前缀开销与工作频率接近波导截止频率之间的关键依赖关系。进一步地，针对基于路径损耗最小化的近似夹持天线定位策略，推导了OFDM夹持天线系统中子载波间的相位失配效应，表明更宽的带宽和更大的阵列规模会加剧相位失配。数值结果表明：1) OFDM夹持天线系统中的频率选择性效应导致子载波可达速率存在显著变化，凸显了工作频率需高于波导截止频率以实现有效通信的必要性；2) 在接近截止频率工作时，波导色散要求相当大的循环前缀开销，严重影响了OFDM夹持天线系统的频谱效率；3) 实际夹持天线系统中平缓的线性波导衰减相较于固定位置天线严重的对数路径损耗特性具有显著优势。