Compact self decoupled MIMO antenna pairs covering 3.4–3.6 GHz band for 5G handheld device applications

Abstract

A self-decoupled 4-port multiple-input multiple-output (MIMO) antenna pair working in the midband of the 5G spectrum (3.5 GHz) for handheld device application is presented in this paper. The antenna includes two vertically placed blocks printed exactly at the middle of the two lengthy frames of the handheld device. The self-decoupled antenna pair structure consists of two monopole antenna separated by a distance of 7 mm, a T-shaped parasitic structure, and a stub at the backside connecting the ground plane. The monopole antennas are excited by a simple coaxial feeding structure. The T-shaped element not only serves as a radiator but plays a vital role in providing port isolation between the two ports to obtain a self-isolated antenna pair. The self-decoupled antenna pair operates from 3.4 to 3.6 GHz with isolation higher than −16.5 dB in the entire utilization band. The parametric analysis of the optimal parameters and the evolution design of the antenna pair is studied for a better interpretation of the working principle of the MIMO system. The total efficiency and peak gain of all the antennas are more than 78% and 5 dB respectively in the whole utilization bandwidth. The worst-case envelope correlation coefficient (ECC) value among the elements of the antenna pair is less than 0.03, which is less than the ideal value of 0.5. Other MIMO diversity parameters such as Channel Capacity Loss (CCL), Mean Effective Gain (MEG), Total Active Reflection Coefficient (TARC), and Diversity Gain (DG) of the designed antenna are calculated and analyzed with the measured results. A model of the designed handheld device is fabricated and analyzed. The measured results indicate the suitability of the design for a capable candidate in 5G handheld device applications.