Compact Eight-Element Antenna Array for Triple-Band MIMO Operation in 5G Mobile Terminals

In this paper, we have introduced a compact eight-element antenna array for triple-band MIMO (multi-input multi-output) operation in 5G (fifth generation) mobile terminals, which consists of two symmetric four-element sub-arrays disposed, respectively, along two long side-edges of the system ground plane of the mobile terminal. This antenna element can operate at two dual-wideband of 3250-3820 MHz and 4790-6200 MHz with three resonance frequencies which can fully cover 5G NR (New Radio) BandN78 (3300-3800 MHz), China 5G-Band of 4800-5000 MHz and LTE Band-46 (5150-5925 MHz). The main parameters that characterize the performance of the proposed MIMO antenna system, such as bandwidth, reflection coefficient, isolation (more than 10.5 dB), total radiation efficiency (more than 43%), ECC (envelope correlation coefficient, less than 0.12) and CC (channel capacity, 34.9-37.6 bps/Hz), are analyzed and presented in this paper. Besides, the effects of single-hand and dual-hand on performance of the MIMO antenna system are also discussed. The structure of antenna element is only 15 mm × 3 mm (0.175 λ
₀
× 0.035 λ
₀
, λ
₀
is the free-space wavelength at the frequency of 3.5 GHz) with a very small ground clearance of 13 mm × 2 mm on the main board of the proposed mobile terminal. The antenna system has the possibility to be used in 5G mobile terminals with triple-band operation, narrow frame and large display. The corresponding antennas prototype is fabricated and measured; and a quite good agreement between simulation and measurement is obtained.