A Compact Dual-Band and High-Isolation MIMO Antenna System for 5G Smartphone Applications

In this paper, a compact dual-band multiple-input multiple-output (MIMO) antenna system with high element isolations is designed for 5G smartphone applications. The MIMO antenna system is composed of 8 loop antenna elements operating at 3.5-GHz band (3400–3600 MHz) and 5-GHz band (4800–5000 MHz), and each of them has compact size of 6.9 × 6.6 mm
²
(about 0.08A × 0.08λ). Each loop antenna consists of two folded stubs that are embedded on the smartphone frame, and is excited by coupling with an inverted L-shape microstrip probe through gaps on the frame. Electromagnetic simulation shows that in the desired two bands the designed MIMO antenna system exhibits high element isolations of over 14.5 dB, without using any decoupling structure, and envelope correlation coefficients of lower than 0.2.