High-efficiency scheme and optimisation technique for design of fragment-type isolation structure between multiple-input and multiple-output antennas

Fragment-type structure has found its application in designing high isolation structure for multiple-input and multiple-output (MIMO) system. In this study, a novel design scheme and a high-efficiency optimisation searching technique for fragment-type isolation structure are proposed based on multiobjective evolutionary algorithm based on decomposition combined with enhanced genetic operators (MOEA/D-GO). Both considering non-uniform fragment cells in design space and combining two-dimensional median filtering operator in the original MOEA/D-GO can improve speed of optimisation searching while obtaining higher isolation and better envelope correlation coefficient at expense of capacity loss. With the high-efficiency optimisation search, more design objectives including the beam direction can be handled as well. The proposed design scheme and high-efficiency searching technique are demonstrated through design examples with two MIMO planar inverted-F antennas operating at 2.345-2.36 GHz and having a centre-to-centre interval of 15 mm. Comparison results among three designs verify the high effectiveness of the proposed scheme and optimisation searching technique.