Four-element MIMO antenna with refined isolation thanks to spiral resonators

To relieve the performance degradation of a 4×4 Multiple-Input Multiple-Output system caused by the strong mutual coupling among the four patch elements, a metamaterial spiral resonator (SR) is proposed as an effective solution. Applying the proposed periodic structure in the substrate and between the patches is simulated and studied. This design could be used to develop a more compact multi-antenna Wi-Fi (IEEE 802.11n) system at 5.5 GHz.