RESUMO
An ultrathin dual-band eight-element multiple input-multiple output (MIMO) antenna operating in fifth-generation (5G) 3.4-3.6 GHz and 4.8-5 GHz frequency bands for future ultrathin smartphones is proposed in this paper. The size of a single antenna unit is 9 × 4.2 mm2 (0.105 λ × 0.05 λ, λ equals the free-space wavelength of 3.5 GHz). Eight antenna units are structured symmetrically along with two sideboards. Two decoupling branches (DB1 and DB2) are employed to weaken the mutual coupling between Ant. 1 and Ant. 2 and between Ant. 2 and Ant. 3, respectively. The measured -10 dB impedance bands are 3.38-3.82 GHz and 4.75-5.13 GHz, which can entirely contain the desired bands. Measured isolation larger than 14.5 dB and 15 dB is obtained in the first and second resonant modes, respectively. Remarkable consistency between the simulated and measured results can be achieved. Several indicators, such as the envelope correlation coefficient (ECC), diversity gain (DG), total active reflection coefficient (TARC), and multiplexing efficiency (ME), have been presented to assess the MIMO performance of the designed antenna.
RESUMO
This article reported a compact ultra-thin tightly arranged 4 × 4 multiple-input multiple-output (MIMO) antenna pair (AP) functioning in the fifth-generation (5G) n78 band (3.4-3.6 GHz) for the ultra-thin 5G mobile handset. Two APs were printed on the center of two sideboards. A T-shaped open-ended slot was utilized in the grounding plane to improve the port impedance matching and attenuate the reciprocal magnetic coupling. A minimized total volume of 145 × 75 × 5 mm3 was obtained, and the area of each radiating unit was only 8.5 × 4.2 mm2 (0.1λ0 × 0.05λ0, λ0 is the free-space wavelength at the frequency of 3.5 GHz). By placing two radiating elements in an exceeding closed (1 mm or 0.01167λ0) distance, the designed AP precisely resonated at 3.5 GHz, and an acceptable measured isolation performance superior to 17 dB was attained. A prototype of this presented APs system was printed and tested, and remarkable consistency was observed between the simulated and measured curves. Numerous indicators were computed to assess its MIMO performance, such as Envelope Correlation Efficiency (ECC), Diversity Gain (DG), Total Active Reflection Coefficient (TARC), and Multiplexing Efficiency (ME).
