Transmission line based decoupling methods for MIMO and phased arrays

Authors: Yiming Zhang, Shuai Zhang

Source: FERMAT, Volume 37, Communication 2, Jan.-Feb., 2020

Abstract: As the key technologies in future 5G cellular communication systems, millimeter wave (mmwave) will be applied for 5G mobile handsets. In these systems, beam steerable arrays with high gain have to be utilized at both base stations and user terminals in order to overcome the path loss. In mobile terminals, there is very limited space left for 5G arrays after accommodating 2G, 3G and 4G antenna systems. The only power supply in a cellphone is a small battery, which requires low-loss and low-cost beamforming. Moreover, user’s mobility and blockage also rise some more new issues. This presentation will introduce the challenges in mm-wave 5G mobile handsets. As some examples, recent progress of the antenna group at Aalborg University will be introduced in the area of mm-wave beam-steerable antenna arrays and their biological effects for 5G mobile terminals. In the base stations, massive MIMO is widely used in sub 6 GHz and in mmwave in the future. The mutual coupling between array elements is highly preferred to be lower than – 25 dB in consideration of active VSWR and system requirements. Moreover, the decoupling method should also be wideband and without significantly impacting the radiation patterns of array elements.

Index Terms: mmwave antenna array, mobile handset, massive MIMO antenna, base station, mutual coupling

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Transmission line based decoupling methods for MIMO and phased arrays