Closely-coupled MIMO antenna with high wideband isolation using decoupling circuit

In this paper, a design and modeling of a closely-coupled MIMO antenna using a new simple wideband decoupling circuit based on a 2nd order filter for isolation improvement are presented to decouple the dual-element/four-element wideband MIMO antenna array. The dual-element wideband MIMO antenna and the wideband decoupling circuit are designed using the structure's admittance parameter. It is used further to extend the system for a larger array. The four-element wideband MIMO antenna is created using a back-to-back arrangement of dual-element MIMO antenna without any extra decoupling circuits. The presented MIMO antenna is resonating at 5.12-5.9 GHz (WLAN) bands. The measured S-parameters of the proposed dual-element/fourelement wideband MIMO antenna offer isolation (>20 dB). The envelope correlation coefficient (ECC) is less than 0.04, and channel capacity loss (Closs) is less than 0.05, along with good radiation characteristics. To explore the packaging aspect of the proposed solution, device housing, and the extended ground effect is also examined. The proposed MIMO antenna shows flexibility to integrate with a large printed circuit board (PCB) concerning placement and shape. It demonstrates an outstanding development that makes the proposed solution the right candidate for advanced technological applications such as 5G and IoT.