Flexibly Extensible Planar Self-Isolated Wideband MIMO Antenna for 5G Communications

A planar flexibly extensible multiple-input–multiple-output (MIMO) antenna array with a self-isolation property is proposed. The main characteristics of the proposed array are: (i) no extra isolation structure is required to improve isolation between elements; (ii) elements are arranged with each other with a spacing of 0 mm, (iii) the configuration can be flexibly extended to a large antenna array according to actual requirements. For a test example, the practical processing and testing of an eight-element array is conducted. The tested results demonstrate that the proposed design possesses wide impedance bandwidth (IBW) of 65% and very good isolation (>18 dB) across the operating bandwidth, which match well with the simulated ones. Moreover, envelope correlation coefficient (ECC) is calculated to valuate MIMO performance; an acceptable ECC (lower than 0.05) suggests that the proposed configuration has good diversity performance and can be a potential candidate for MIMO communications.