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

Abstract

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.

Design and SAR assessment of three compact 5G antenna arrays

“… – 9.485 1.42 0.3 22 N.A N.A. 2 × 2 12.3 – 0.37 36 N.A 24 MIMO 10 – Max:1.2 8 × 8 – Min:0.8 Ant. 1 5 mm 15 1 × 8 12.85 0.56 0.15 Ant.…”

Evaluation of Development Level and Technical Contribution of Recent Technologies Adopted to Meet the Challenges of 5G Wireless Cellular Networks

“…To meet the current requirements and those of the future due to the growth of connected objects known by various categories of use, the new 5G standard has responded to the deficits related to the increased throughput or bandwidth and has achieved an ultra-short latency and reduced power consumption with ubiquitous quality service [29]. This has been accomplished by the introduction of different technologies and even by the combination of several of them [30,31].…”

“…Unlike this antenna consisting of a monopole operating in 3.1-3.85 and 4.8-6 GHz for the low band and the high band respectively, another dipole frequency-reconfigurable antenna has shown two resonant modes centered at 3.5 and 5.5 GHz or, to be more specific, two bandwidths that are 2.89-4.07 GHz and 5.1-6.19 GHz [36]. Otherwise, some researchers have dealt with cases treating the combination of mmWave and Sub-6 GHz for 5G antenna systems [30,37]. Here, it is important to mention that the use of mmWave technology is primarily motivated by the fact that the sub-bands 6 GHz are almost saturated.…”

“…The technical justification for this choice lies in the fact that the main gains, in terms of the performance and efficiency of 5G, are based on the portions of the spectrum that are around WiFi [34]. Therefore, service providers can take advantage of frequencies below 6 GHz as a new exploitable spectrum, ensuring wider channels and better latency [29][30][31][32][33][34][35]. However, the major problem of this frequency band is that a large part of its spectrum is in free use and that the interference problem caused by the multitude of users must be solved.…”

“…The received power (P rx ) by a wireless system can be expressed as a dependence on the transmitted power (P tx ), the distance between the antennas (R) and the transmit (G tx ) and receive (G rx ) gains according to the Friis Equation (7) [30]:…”