Suppressing mutual coupling of MIMO antennas with parasitic fragment-type elements

Parasitic fragment-type element can be used in suppressing mutual coupling of multiple-input multiple-output (MIMO) antennas. By gridding a specific design space between MIMO antennas into fragment cells, and metalizing some of the cells selected by multi-objective optimization searching, parasitic fragment-type isolation element can be designed to acquire desired isolation and return losses. For demonstration, a parasitic fragment-type isolation element for closely spaced printed monopoles operating at 2.45 GHz is designed and verified by test. The proposed parasitic fragment-type element achieves maximum isolation 29 dB, and isolation higher 16 dB in the operation band. Besides, due to its flexibility and versatility, fragment-type structure can be applied in forming miniaturized element of high isolation.