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
A multiple-input-multiple-output (MIMO) antenna array for triple-band 5G metal-frame smartphone applications is proposed in this paper. Each single antenna element consists of an S-shaped feeding strip and an L-shaped radiation strip on the metal frame. The dimension of the antenna element is only 6.5 mm × 7 mm (0.076 λ0 × 0.082 λ0, λ0 is the free-space wavelength at the frequency of 3.5 GHz). The -6 dB impedance bandwidth of the proposed eight-antenna array can cover 3.3-3.8 GHz, 4.8-5 GHz, and 5.15-5.925 GHz. The evolution design and the analysis of the optimal parameters for a single antenna element are derived to investigate the principle of the antenna. The measured total efficiency is larger than 70%. The measured isolation is better than 13 dB. The measurements of the prototype agree well with the simulation results.
