Isolation enhancement of small-size WLAN MIMO antenna array for laptop computer application

This paper proposes a multiple-input multiple-output (MIMO) antenna array comprising two compact wireless local-area network (WLAN) antennas with high isolation in between. The two operating frequency bands are designed to completely enclose the 2.4/5.2/5.8 GHz WLAN bands. The MIMO antenna array having a small size, a low height, and a small thickness is especially suitable to be installed in ultra-thin notebook computers. The size of the designed antenna array has been reduced to about 40% than those of the MIMO arrays appearing in the recent literature. The designed isolation element between the two radiating antennas consists of two resonant slots, the lengths of which are individually a quarter-wavelength at 2.45 and 5.5 GHz. The isolation elements block the horizontal surface currents on the system ground plane, leading to mutualcoupling reduction between the two source antennas and hence excellent isolation between them. Results indicate that the proposed MIMO antenna array has good characteristics of antenna radiation efficiency, and impedance matching in the two bands of interest.