Massive multiple input–multiple output (MIMO) antenna is required to meet the high data transmission rate in the current 5G and future 6G mobile communication. This paper presents a novel eight-port dual-band MIMO antenna operated within the 5G new radios N77 and N79 band. The designed MIMO incorporates a self-decoupling method to obtain high isolation of 22.96 and 25 dB at the two resonances 3.48 and 4.92 GHz, respectively. The basic antenna element consists of coupling between a staircase slot and a half-wavelength size loop branch. Additionally, an inverted U-shaped microstrip section is integrated with the radiating unit to serve the purpose of self-decoupling operation. The eight antennas are symmetrically located on the two narrow substrates (of size 5.8 × 150 mm2) as a pair of four arrays. The narrow substrates make the metal rim of the 5.5″ display mobile smartphone. The designed MIMO is practically realized and experimentally tested to validate the working mechanism. The envelope correlation coefficient and peak channel capacity are obtained as 0.174 and 35.5 bps/Hz in the lower frequency and 0.069 and 39.1 bps/Hz in the higher frequency.

For future fifth-generation (5G) smartphones, a high-efficiency multiple-input/multiple-output (MIMO) antenna system capable of operating in Long Term Evolution (LTE) 42/43/46 is suggested. A pair of small microstrip-fed slot antenna and inverted F antenna is part of the single antenna design structure. They are positioned on the longer side of the FR-4 printed circuit board. In an effort to lessen the mutual coupling, two antenna elements have a U-shaped rectangular slot inserted between them. The detailed study of the suggested MIMO system includes measurement of the reflection parameter, analyzing the radiation performance, performing envelope correlation coefficient (ECC) and channel capacity calculations, and analyses of the effects of user’s hand in the vicinity of the antenna array. Simulation and measurement results demonstrate the required performance of the proposed design, that is, greater than 80% of total efficiency, isolation >12 dB, and ECC <0.15. The suggested antenna has the benefits of multiband operation, high efficiency, good isolation, and a small footprint.