High Isolation 8⨯8 MIMO Antenna Design for 5G Sub-6 GHz Smartphone Applications

In this paper, an $8\times 8$ Multiple Input Multiple Output (MIMO) antenna design for Fifth Generation (5G) sub-6GHz smartphone applications is presented. The antenna elements are based off a folded quarter wavelength monopole that operate at 3.4-3.8GHz. Isolation between antenna elements is provided through physical distancing. The fabricated antenna prototype outer casing is made from Rogers R04003C with dimensions based on future 5G enabled phones. Measured results show an operating bandwidth of 3.32 to 3. $925\mathrm{G}\mathrm{H}\mathrm{z}(\mathrm{S}_{11}\lt$ -6dB) with a transmission coefficient $\lt_{-}14.7\mathrm{d}\mathrm{B}$. A high total efficiency for an antenna array is also obtained at 70-85.6%. The design is suitable for MIMO communications exhibited by an Envelope Correlation Coefficient (ECC) $\lt0.014$. To conclude a Specific Absorption Rate (SAR) model has been constructed and presented showing the user’s effects on the antenna’s S-parameter results. Measurements of the amount of power absorbed by the head and hand during operation have also been simulated.