Wideband Aperture-Overlapped MIMO Antennas Naturally Integrating Mode Orthogonal and Parasitic Decoupling Schemes

In this letter, a wideband self-decoupling scheme is proposed for MIMO antennas. Based on the mode orthogonal decoupling scheme, when the proposed differential mode antenna is integrated with a loop branch, it will be decoupled at one frequency
f
₁
. Moreover, the parasitic branch in the proposed antenna naturally works as a parasitic decoupling element, so it will achieve decoupling at a second frequency
f
₂
simultaneously. Two demonstrational examples working in the N79 band (4.4 – 5 GHz) are studied. The results show that the MIMO antennas using the proposed scheme can achieve a wideband isolation greater than 26.4 dB across the whole band with two transmission zeros. Taking into consideration the attractive integration free from differential feeding structures and wideband high isolation, the proposed integrating decoupling scheme may provide a new vision for the MIMO antenna designs.