Multi-Mode Pinching-Antenna Systems: Polarization-Aware Full-Wave Modeling and Optimization

2026-04-02

AI Summary

This study addresses the challenge of simultaneously mitigating severe path loss and maximizing spectral efficiency in millimeter-wave and terahertz communications. To this end, it proposes the first full-wave electromagnetic modeling framework that integrates multimodal propagation with polarization awareness, uniquely unifying polarization states and multimodal characteristics within a single physical model. This formulation reveals the intrinsic trade-offs among waveguide attenuation, atmospheric absorption, and geometric spreading. Building upon this model, the authors develop a closed-form polarization update algorithm and a modular optimization strategy to enable accurate modeling and efficient deployment of near-user antenna systems. Experimental results demonstrate that the proposed approach achieves up to a 167% improvement in spectral efficiency over single-mode systems, with polarization awareness alone contributing a 23% gain in aggregate data rate.

Abstract

Millimeter-wave and terahertz communications face a fundamental challenge: overcoming severe path loss without sacrificing spectral efficiency. Pinching antenna systems (PASS) address this by bringing radiators physically close to users, yet existing frameworks treat the waveguide as a mere transmission line, overlooking its inherent multi-mode capabilities and the critical role of polarization. This paper develops the first polarization-aware, full-wave electromagnetic model for multi-mode PASS (MMPASS), capturing spatial radiation patterns, modal polarization states, and polarization matching efficiency from first principles. Leveraging this physically grounded model, we reveal fundamental trade-offs among waveguide attenuation, atmospheric absorption, and geometric spreading, yielding closed-form solutions for optimal PA placement and orientation in single-user scenarios. Extending to multi-user settings, we propose a modular optimization framework that integrates fractional programming with closed-form polarization updates, scaling gracefully to arbitrary numbers of waveguides, PAs, and users. Numerical results show that MMPASS achieves up to a 167% increase in spectral efficiency compared with single-mode PASS. Moreover, when comparing MMPASS with its polarization-ignorant counterpart, polarization awareness alone improves the sum rate by up to 23%. By bridging rigorous electromagnetic theory with scalable optimization, MMPASS establishes a physically complete and practically viable foundation for future high-frequency wireless networks.

Problem

• millimeter-wave communications
• terahertz communications
• pinching antenna systems
• polarization
• multi-mode waveguide

Innovation

• multi-mode pinching antenna
• polarization-aware modeling
• full-wave electromagnetic simulation
• spectral efficiency optimization
• millimeter-wave/terahertz communications