The mutual coupling among the antenna elements keeps the antennas from radiating appropriately. Which means it could result in negative impact on the overall gain.

If the primary objective is to increase antenna gain, isolation techniques alone are insufficient. Instead, approaches such as designing higher-gain antenna elements, incorporating reflectors or directors, and optimizing impedance matching should be prioritized. On the other hand, if the goal is to enhance MIMO performance, improve diversity gain, and reduce the ECC value, achieving strong isolation is critically important.

Hello Qahtan Mutar Gatea, isolation methods in MIMO don’t directly boost antenna gain. They mainly improve port isolation, ECC, and efficiency, helping maintain performance by reducing coupling losses. If gain is the goal, focus on the radiating element design and array geometry instead.