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arXiv · 2601.18471

Finite-Aperture Fluid Antenna Array Design: Analysis and Algorithm

Zhentian Zhang·Kai-Kit Wong·Hao Jiang·Farshad Rostami Ghadi·Hyundong Shin·Yangyang Zhang
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Abstract

Finite-aperture constraints render array design nontrivial and can undermine the effectiveness of classical sparse geometries. This letter provides universal guidance for fluid antenna array (FAA) design under a fixed aperture. We derive a closed-form Cram\'er--Rao bound (CRB) that unifies conventional and reconfigurable arrays by explicitly linking the Fisher information to the geometric variance of port locations. We further obtain a closed-form probability density function of the minimum spacing under random FAA placement, which yields a principled lower bound for the minimum-spacing constraint. Building upon these analytical insights, we then propose a gradient-based algorithm to optimize continuous port locations. Utilizing a simple gradient update design, the optimized FAA can achieve about a $30\%$ CRB reduction and a $42.5\%$ reduction in mean-squared error.

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Zhentian Zhang, Kai-Kit Wong, Hao Jiang, Farshad Rostami Ghadi, Hyundong Shin, Yangyang Zhang. 2026-01-26. Finite-Aperture Fluid Antenna Array Design: Analysis and Algorithm. https://doi.org/10.1109/lwc.2026.3685911

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