A DESIGN OF ANTENNA ARRAY WITH IMPROVED PERFORMANCE FOR FUTURE SMARTPHONES

In this study, a new multiple-input-multiple-output (MIMO) antenna array is introduced for fifth-generation (5G) smartphones. Its schematic contains eight planar invertedF antenna (PIFA) elements placed at edges of the mobile-phone mainboard with a 75 × 150 × 0.8 mm3 FR-4 substrate. The ground plane and antenna resonators are etched on the back layer of the mainboard. By employing arrow strips between the adjacent elements, the frequency bandwidth and isolation level of the PIFA radiators are improved. The proposed smartphone antenna array is designed to support the spectrum of commercial sub 6 GHz 5G communication and cover the frequency range of 3.25–3.85 GHz with isolation levels better than −15 dB. Due to the compact size and corner placements of the PIFAs, the presented MIMO antenna array occupies a small part of the board. In addition, the proposed smartphone antenna array provides not only sufficing radiation coverage supporting different sides of the mainboard but also the polarization diversity. The MIMO performance and characteristics of the proposed smartphone antenna design in the presence of the user phantom are also discussed.