In the paper, the design of MIMO antennas with three ports is proposed and investigated. The three monopole antennas are fed by 50-ohm mini coaxial cable lines. Three monopoles are located as the right, the middle and the left side of the top edge of the design. Two L-shaped strips protruded from the ground and four inverted L-shaped strips extended from the ground is introduced to the design for enhancing isolation between them and impedance matching. From the measured results, the operating bands of 5.15-5.35GHz cover the bands of IEEE802.11 ac applications. The simulated and measured results are compared and discussed.