Design of Wideband Decoupling Networks for MIMO Antennas Based on an N-Ary Optimization Algorithm

Techniques for reducing the coupling between antenna elements in multiple-input multiple-output (MIMO) systems are important for achieving the full potential of MIMO. In this article, a general and systematic method is developed to design a wideband decoupling and matching network (DMN) for MIMO antenna arrays. The DMN is formed by grid-like transmission lines interconnected by lumped components, whose reactances can be obtained from anN-ary optimization algorithm. Four design benchmarks are performed for validating decoupling methodology, elaborating on design/implementation procedure, and demonstrating superiority of the proposed method. Results show that the DMN achieves broad isolation bandwidth while occupying a small footprint area. Besides, the DMN is applicable for symmetric, asymmetric, and multi-element MIMO antenna arrays. In comparison to prior works, the proposed DMN offers a wider isolation bandwidth, higher efficiency, and comparable size.