Meta-Fluid Antenna-Enabled Multi-User ISAC: Architecture Implementation, Algorithm Design, and Full-Wave Validation

This paper introduces a novel meta-fluid antenna (MFA) architecture for multi-user integrated sensing and communication (ISAC) systems. For architecture implementation, we propose a PIN diode-integrated substrate-integrated waveguide (SIW) structure that enables dynamic antenna reconfiguration through electronic control. The design features 120 independently controllable elements arranged in a 7λ × 4λ array, achieving efficient radiation control (13.5 dB in ON state, 0.5 dB in OFF state) while maintaining single radio-frequency (RF) chain simplicity. In terms of algorithm design, we develop two key innovations: a sparsity-driven inverse scattering algorithm for high-resolution sensing, and a single-RF multi-pattern activation (SRMPA) scheme for intelligent interference management in multi-user scenarios. The SRMPA scheme dynamically optimizes antenna activation patterns without requiring complex precoding or additional RF chains, while the inverse scattering algorithm enables accurate reconstruction of spatial information from limited measurements. Through full-wave validation, we comprehensively evaluate the system using three-dimensional electromagnetic simulations at 26.5 GHz. The results demonstrate exceptional sensing performance, achieving a peak signal-to-noise ratio (PSNR) of up to 21.81 dB and a structural similarity index measure (SSIM) of 0.94. Additionally, significant improvements are observed in key communication metrics, including reduced outage probability and enhanced multiplexing gain. These findings establish the proposed MFA-enabled multi-user ISAC architecture as a practical solution for future ultra-dense wireless networks, particularly within the evolving landscape of sixth-generation (6G) wireless communication.