Compact MIMO Antenna for 5G Portable Device Using Simple Neutralization Line Structures

In this paper, a 4×4 multiple-input-multiple-output (MIMO) antenna array incorporating a neutralization line (NL) with a compact size of only 40 mm×40 mm×6 mm is proposed. This MIMO array is covered in the Chinese 5G bands (3300-3600 MHz and 4800-5000 MHz), LTE band 43 (3600-3800 MHz) and 5.8-GHz WLAN band (5725-5875 MHz). The four antenna elements which consist of monopole and loop structures are located on the corners of the system. The neutralization line mounted on the outside of the border occupies very little board space, and the design requires no modification to the ground plane for mitigating mutual coupling.