High-Isolated MIMO Antenna Design Based on Pattern Diversity for 5G Mobile Terminals

In this letter, a novel multiple-input–multiple-output (MIMO) antenna operating at 3500 MHz band is presented for 5G mobile terminals. The proposed antenna includes four blocks. Each block consists of two face-to-face elements with total size of 25 × 3.5 mm
²
. Rather than excited separately, the two elements are excited simultaneously. Pattern diversity is achieved by using in-phase and out-of-phase signals. A compact two-port feed network is designed to provide the required feed signals. The measured bandwidth for the two ports is 750 MHz (3.06–3.81 GHz) and 340 MHz (3.33–3.67 GHz), which is sufficient to cover the 3400–3600 MHz band. The port isolation is higher than 14 dB in the overlapping bandwidth.