Sequentially Rotated Four-Element Planar MIMO Array for 5G Cellular Communications

Here, a 2 × 2 MIMO array of a sequentially rotated monopole antenna (SRMA) is proposed for cellular communication. The proposed four-element array is designed with a single modified planar monopole antenna (MPMA). Over a partial ground plane, three semi-circular slots are designed on the top patch to propose the antenna for reserving the 5G Sub-6 GHz NR frequency Bands n77/n78/n79 (
$S$
11
< −10dB). The antenna offers a gain of 3 dBi (realized) with a radiation efficiency better than 95% by a quasi-omnidirectional radiation pattern. Afterwards, the antenna is used to configure a 2 × 2 MIMO array on a 150×75 mm
²
smartphone mainboard with polarization diversity. The proposed MIMO has more than 21 dB isolation among the antenna elements. The array of this work exhibits 5.5 dBi peak gain with a quasi-omnidirectional radiation pattern to all four directions of the phone board. Moreover, an excellent envelop correlation coefficient below 0.0012 and diversity gain of around 10 are found with the MIMO array for the whole operating bandwidth. The design proposed in this work should motivate the researcher and industrial engineers to develop MIMO arrays with high performance in 5G smartphones.