Super-compact 28/38 GHz 4-port MIMO antenna using metamaterial-inspired EBG structure with SAR analysis for 5G cellular devices

• Main Authors: Al Gburi, Ahmed Jamal Abdullah, Elabd, Rania Hamdy
• Format: Article
• Language: English
• Published: Springer 2024
• Online Access: http://eprints.utem.edu.my/id/eprint/27238/2/027022702202413210718.PDF; http://eprints.utem.edu.my/id/eprint/27238/; https://link.springer.com/article/10.1007/s10762-023-00959-6
• Institution: Universiti Teknikal Malaysia Melaka

Maintaining the compact form of 5G smartphones while accommodating millimeter-wave (mm-wave) bands is a significant challenge due to the substantial frequency difference. To address this issue, we’ve introduced an super-compact 4-port dual-band multiple-input, multiple-output (MIMO) antenna that utilizes a metamaterial-inspired electromagnetic bandgap (EBG) structure. This design minimizes mutual coupling (MC) and handles a wide frequency range effectively. The 4-port MIMO antenna is constructed on a Rogers TMM4 substrate, with overall dimensions of 17.76 × 17.76 mm². It incorporates four planar patch antennas positioned at the corners, arranged perpendicularly to each other. Each antenna element is designed for dual-band operation at 28/38 GHz, featuring a rectangular patch with four rectangular slots and a full ground plane. The gap between these patches measures 0.5 λo, and an EBG is included to minimize MC among the MIMO antenna elements efficiently and cost-effectively. Both simulation and measurement results show a substantial reduction in mutual coupling between the array elements, ranging from −25 to −90 dB. Consequently, this enhances the envelope correlation coefficient (ECC) and improves the total active reflection coefficient (TARC), mean effective gain (MEG), and diversity gain (DG). An in-depth time-domain analysis is proposed to confirm the radiation efficiency of the proposed MIMO antenna design. Furthermore, specific absorption rate (SAR) analysis affirms the suitability of this MIMO antenna for 5G cellular devices operating within the target frequency band.