Integration of Sub-6-GHz and mm-Wave Bands With a Large Frequency Ratio for Future 5G MIMO Applications

• Published in: IEEE access 2021, Vol.9, p.11241-11251
• Main Authors: Zada, Muhammad, Shah, Izaz Ali, Yoo, Hyoungsuk
• Format: Article
• Language: English
• Subjects: 5G mobile communication; Antennas; Applications programs; Banded structure; Decoupling; Electronic devices; Frequencies; Frequency reconfigurability; Ground plane; Microstrip; Microstrip antennas; Millimeter waves; MIMO; MIMO (control systems); mm-wave; Mobile antennas; Mobile computing; PIN diodes; PIN photodiodes; power density; Safety; Size reduction; smartphones; specific absorption rate; sub-6-GHz; truncated ground structure; Wireless communication; Wireless communications
• ISSN: 2169-3536; 2169-3536
• DOI: 10.1109/ACCESS.2021.3051066

The integration of sub-6-GHz and millimeter-wave (mm-wave) bands has become an important issue for future fifth generation (5G) wireless communications owing to their large frequency ratios. This paper proposes a compact-size dual-function antenna operating at 3.5 GHz and the mm-wave band (28 GHz) for 5G mobile applications using a frequency reconfigurability technique. The proposed antenna comprises a microstrip patch linked with a meandered radiating structure through a radio frequency PIN diode to achieve frequency reconfigurability between the two bands. A significant size reduction up to 15.3 mm × 7.2 mm × 0.508 mm for the proposed antenna was achieved using a meandered line structure and truncated ground plane. To enhance the functionality, 8 × 8 multiple-input multiple-output (MIMO) with possible long- and short-edge antenna placement configurations were demonstrated. The system exhibited satisfactory MIMO characteristics with wide decoupling -10 dB bandwidths of 7.4% and 4.8% at the low- and high-frequency bands, respectively, without utilizing any external decoupling structure. The simulated results were validated using fabricated prototypes, and good agreement was observed. Additionally, a safety analysis based on the specific absorption rate and power density at the prescribed frequency bands was conducted using a realistic human model, and the results were found to be in accordance with the safety guidelines. Owing to the integration of sub-6-GHz and mm-wave bands in a single compact structure with a large frequency ratio and good MIMO performance, the proposed antenna system is suitable for future 5G mobile handheld devices.