Compact MIMO Four-Antenna Module Formed by Two Mirrored Dual-Polarized Antennas for 6G U6 GHz Mobile Device Applications

For future six generation (6G) mobile communications, the industry envisions that the user experienced spectral efficiency be at least twice that of today’s fifth generation (5G) networks. We expect that this 6G vision can be realized in the upper 6 GHz (U6 GHz, 6.425-7.125 GHz), if much more MIMO antennas in future mobile devices than the spatial streams can be implemented for higher-order MIMO communications. For this motivation, to deploy much more antennas in the limited space of 6G mobile devices, we propose a compact four-antenna (C4A) module having a smaller size than the conventional four-antenna modules with either 2 × 2 or 1 × 4 configuration. The C4A module consists of two mirrored dual-polarized antennas with decreased radiation correlation to provide four uncorrelated MIMO antennas with a small size of 0.29λ2covering the U6 GHz. Additionally, the envelope correlation coefficient of any two antennas in the C4A module is less than 0.14 and the port isolation is larger than 10 dB over the U6 GHz. We further demonstrate using three C4A modules to achieve 12 MIMO antennas in a smartphone-like mobile device. We then assess higher-order MIMO communications including the 8 × 4 and 12 × 4 MIMO with 4 spatial streams. We obtain a large spectral efficiency up to 37 bps/Hz, which is more than twice that of today’s 5G network and can thus lead to increased user-experienced data rates for 6G users. In this article, we present details of the C4A module to achieve smaller size yet decreased radiation correlation and enhanced port isolation as well. We also demonstrate that higher-order device MIMO communications based on applying the C4A modules are promising to achieve increased data rates for the 6G user.