Floquet spectral–spatial modulation using Fourier contours and windowing for multi‑beam control in next‑generation wireless systems

Abstract This paper introduces a unified approach for modeling and synthesizing multi-beam radiation patterns in large, strongly-coupled antenna arrays. The method combines Floquet spectral analysis with Fourier-based contour windowing to efficiently handle both regular and arbitrarily-shaped array layouts. Starting from a single unit cell described by periodic (Floquet) boundary conditions, the electromagnetic response of the entire array is reconstructed via spectral modulation and inverse Fourier transformation. The formulation is solver-agnostic and compatible with numerical methods including the Method of Moments, its equivalent circuit variant, the Finite-Difference Time-Domain, and the Finite Element Method. The proposed technique is particularly suited for emerging systems including 6G communication, Massive MIMO, automotive radars, and IoT networks, where beam-forming, beam-steering, and low-cost computation are critical.