Decoupling and Matching Network for Dual-Band MIMO Antennas

This article presents a novel method to design the decoupling and matching network (DMN) for dual-band multi-input–multioutput (MIMO) antennas. The DMN consists of a grid of metallic microstrip stubs, some of which are connected while others are not. The connecting condition in the DMN is the only unknown variable for realizing high antenna isolation. It is determined by rigorous design formulas upon scattering matrix and optimized by the binary optimization algorithm, e.g., genetic algorithm (GA). Thus, high isolation among antennas can be achieved without requiring the optimization process in the electromagnetic simulation tool. Three decoupling examples of two two-element symmetric and asymmetric arrays and a four-element array are presented to elaborate the design procedure and verify the advance of the proposed decoupling method. Results show that the adoption of DMN offers enhancement in impedance matching, isolation, and efficiency, as well as the reduction of envelop correlation coefficient within two desired frequency bands for all cases, validating the proposed decoupling method.