Small Inverted-U Loop Antenna for MIMO Applications

This article presents a novel technique for isolation enhancement between two closely packed antennas. First, an inverted-U loop antenna (IULA) integrated into the top edge of a laptop panel is designed for 2.6-GHz LTE application. The mutual coupling between two designed IULA antennas has considerable effects by the placing positions of them. The results indicate the ground of the two IULA antennas placing against each other obtain the best isolation. At last, a three-element MIMO antenna was designed and measured. Although the gap between two adjacent antennas is only 1 mm, the experimental results show that the proposed two-element and three-element MIMO antennas achieve more than 20 dB isolation within the operating band. The important performances of antenna efficiency, envelope correlation, and channel capacity are also presented.