Flexible Antenna Systems (FAS) are a key enabler of next-generation wireless networks, allowing the antenna aperture to be dynamically reconfigured to adapt to channel conditions and service requirements. In this context, pinching-antenna systems (PASs) implemented on software-controllable dielectric waveguides provide the ability to reconfigure both channel characteristics and path loss by selectively exciting discrete radiation points. Existing works, however, typically assume continuously adjustable pinching positions, neglecting the spatial discreteness imposed by practical implementations. This paper develops a closed-form analytical framework for the ergodic rate of two-state PASs, where pinching antennas are fixed and only their activation states are controlled. To quantify the impact of spatial discretization, pinching discretization efficiency is introduced, characterizing the performance gap relative to the ideal continuous case. Finally, numerical results show that near-continuous performance can be achieved with a limited number of pinching points, providing design insights for scalable PASs.

翻译：柔性天线系统（FAS）是下一代无线网络的关键使能技术，它允许天线孔径动态重构以适应信道条件和服务需求。在此背景下，基于软件可控介质波导实现的夹持天线系统（PAS）能够通过选择性激励离散辐射点，同时重构信道特性和路径损耗。然而，现有研究通常假设夹持位置可连续调节，忽略了实际实现所强加的空间离散性。本文针对二态PAS的遍历速率建立了一个闭式解析框架，其中夹持天线位置固定，仅控制其激活状态。为量化空间离散化的影响，引入了夹持离散化效率这一指标，用以表征相对于理想连续情形的性能差距。最后，数值结果表明，通过有限数量的夹持点即可实现接近连续的性能，为可扩展PAS的设计提供了重要参考。