Wideband Self-Decoupled Slot MIMO Antennas With Two Transmission Zeros

A self-decoupled wideband slot multiple-input-multiple-output (MIMO) antenna pair is proposed in this letter. The two slot antennas are bent into two perpendicular portions, and the current directions on one portion of the two antennas are the same and those on the other ones are opposite to make the total current coupling cancel out with each other, so the first transmission zero is achieved. To widen the decoupling bandwidth, another short-ended slot is introduced around the center point of the original slot antenna to maintain the first transmission zero. Based on the same current coupling cancellation mechanism, a second transmission zero can be generated at this higher frequency, so a wideband self-decoupled MIMO antenna design is achieved. One two-element demonstrational example working in the N78 band (3.3-3.8 GHz) is simulated and measured. The results show that the proposed slot antennas achieve isolation of better than 20 dB and matching conditions of better than −10 dB within the N78 band. Besides, the envelope correlation coefficient is less than 0.006, and the average total efficiency is about 80%. Another four-element linear array is also designed and measured to justify the generality of the proposed method.