In this paper, Characteristic mode analysis is used to design a dual-band (WLAN and WiFi) MIMO antenna. A step by step design procedure is discussed for a proposed structure using CMA modal significance. By analyzing Characteristic angle, eigenvalues and modal significance in systematic design approach, help us to achieve good S 11 (<-10dB) and S 21 (<-15dB) in the desired bands. In the presented work first single band MIMO antenna is evolved by identifying desired resonating modes and undesired non-resonating modes using CMA. The desired single band is achieved by tuning the non-resonating modes in the design. The presence of undesired non-resonating modes influence the mutual coupling between the antenna, and as a result of that, it diminished the performance of MIMO antenna. To minimize the impact of mutual coupling; Defected Ground Structure (DGS) and stubbing in the ground plane is introduced. The proposed design shows good envelope correlation coefficient (ECC), diversity gain, and Gain in the operating bands.