Design of Decoupling and Pattern Shaping Surface for MIMO Antennas Using the Multiport Optimization Method

This article introduces a comprehensive method for designing a decoupling and pattern shaping surface (DPSS) specifically tailored for multiple-input-multiple-output (MIMO) antennas. It addresses the challenge posed by conventional decoupling surfaces, which often lack a systematic design methodology, thereby relying on time-consuming parameter optimization. Constructed from periodic metallic patches on a dielectric substrate and positioned above the coupled array, the DPSS enhances isolation and shapes radiation patterns. Formulas derived from scattering matrices and electric fields inform the determination of connection states between patches, subsequently translated into a binary optimization problem solvable via genetic algorithm (GA). Validation against two benchmarks underscores the efficacy of this approach, demonstrating significant improvements in isolation (below −20 dB), efficiency (over 75%), and a reduced envelope correlation coefficient (ECC), alongside proficient radiation-pattern shaping within the targeted frequency band. Moreover, the DPSS extends its applicability to multielement dual-polarized (DP) arrays, ensuring wideband performance and straightforward implementation.