Mutual coupling cancellation for compact MIMO antenna with 3 dB hybrid

Abstract

MIMO is one of the important technologies in LTE, WiMAX and LTE-Advanced for improving spectrum efficiency. However, it is not easy to make a compact MIMO antenna for portable terminals, keeping high performance. One of the problems is mutual coupling among the antennas. This reduces the efficiency of the antenna. In this paper, a 3 dB hybrid is used to cancel the mutual coupling. This idea can be applied to 2N (N is integer) number of MIMO antennas. In addition, by using tunable impedance matching circuits, wide operational bandwidth is available. Experiments were carried out for 2 MIMO antennas at 2.4–2.6 GHz band.