Quad-Band and Eight-Port MIMO Antenna for 5G Mobile Phones

This paper presents a MIMO antenna specifically designed for 5 G mobile communications. A multi-branch structure is utilized to enhance the operational frequency bandwidth of the antenna. However, multi-band antennas tend to increase inter-band interference, which presents a significant challenge in antenna design. To address this issue, a reverse-branch configuration is implemented to mitigate mutual coupling between the antenna elements. In contrast to most single-band mobile phone antennas, the proposed design achieves full coverage in both sub-6 GHz and millimeter-wave bands. The antenna can operate simultaneously in the 3.3–3.6, 4.8–5.0, 24.75–27.5, and 37–42.5 GHz bands. The isolation between antenna elements is better than –15 dB, the antenna efficiency ranges from 37% to 75%, the envelope correlation coefficient (ECC) is below 0.1, and the specific absorption rate (SAR) is less than 0.05 W/kg.