A dual‐band eight‐antenna multi‐input multi‐output array for 5G metal‐framed smartphones

Abstract

A dual-band eight-antenna array operating in the long-term evolution (LTE) band 41 (2.496-2.69 GHz) and 3.5-GHz band (3.3-3.7 GHz) for fifth-generation (5G) metalframed smartphone is presented. The proposed dual-band antenna array is composed of four identical dual-antenna building blocks (DABBs). Each DABB consists of two identical antenna elements with a neutralization line between them. The antenna array is simulated, fabricated, and measured. The isolations are better than 10.5 dB and 11.0 dB in the low band (LB; LTE band 41) and high band (HB; 3.5-GHz band). The total efficiencies are 41% to 54% and 46% to 64% in the two operation bands, respectively. In addition, the measured envelope correlation coefficients are less than 0.11 and 0.06, the calculated channel capacities are better than 34.5 and 36.3 bps/Hz in the LB and HB, respectively. Furthermore, four hand-grip scenarios are investigated, and results show that proposed antenna array can maintain excellent multipleinput multiple-output performances in all scenarios.Recently, metal-framed smartphones have been embraced by an increasing number of smartphones companies. The metal frame can increase the robustness and strength of the mobile handsets and allow the smartphone to have noble appearances. However, the metal frame can greatly affect the performance of antennas, such as the bandwidth and total efficiency. It poses a great challenge to the design of multiband smartphone antennas with integrated metal frame. As a key technique for 5G communications, the multiple-input multiple-output (MIMO) technology has become a hotspot both in academia and industrial community. MIMO technology has the potential to significantly enhance spectrum efficiency and channel capacity for the 5G communication system without consuming additional bandwidth or transmission power. 1,2 However, it is a challenging task to place multiple antennas in a limited design space while attaining wide bandwidths and desirable radiation performance.The sub-6 GHz bands (5G frequency bands below 6 GHz) are very important for 5G trails and future deployment. Recently, China's Ministry of Industry and Information Technology (MIIT) officially declared the 3.3 to 3.6 GHz frequency spectrum for 5G mobile communication. 3 In addition, South Korea and Australia chose the 3.55-GHz band (3.4-3.7 GHz) for future 5G communication network deployment. American reserved the 3.55 to 3.7 GHz band for future 5G communication spectrum deployment. 4 Among the frequency bands of sub-6 GHz, the long-term evolution (LTE) band 41 (2.496-2.69 GHz) is also a key candidate for 5G sub-6 GHz bands. Recently, it was adopted by the world's main communication equipment suppliers and operators as an existing band for 5G applications. 5 In recent works, some antenna array designs for 5G mobile devices utilize pattern diversity or orthogonal polarization technique to achieve good isolations and low correlations. [6][7][8][9] Other massive MIMO antenna array designs for smartphones applications are reported in References 10...

Wideband MIMO Antenna Array Covering 3.3–7.1 GHz for 5G Metal-Rimmed Smartphone Applications

“…Besides, its ground clearance size (15 mm × 3 mm) is much larger than the proposed work (12.4 mm × 1.5 mm). Apart from wider bandwidth, compared with some 8-antenna arrays, the peak channel capacity of the proposed antenna array is higher than the works reported in [3]- [5], [20]- [22], [27], [29], [42], [44]. In addition, the ECC of the proposed antenna array is also relatively low.…”

“…A rectangular gap is etched on the long side-edge metal rim, which forms an L-shaped slot aperture together with the clearance. Although the side frame is etched, in fact, most antenna designs with integrated metal rims need to be sliced reasonably [5], [9]. For engineering applications, using nano injection and nano molding technologies, plastic can be filled into the gap to ensure the integrity and mechanical strength of the frame.…”

“…In recent years, matching circuit has also been regarded as a handy yet effective approach to enhance bandwidth. An 8-antenna metalrim-integrated MIMO array analyzed in [5] can operate in both LTE band 41 and 3.3-3.7 GHz band through embedding two capacitors into radiation branches. A MIMO antenna based on Composite Right/Left-Handed Transmission Line (CRLH-TL) [6] utilizes a band-stop matching circuit to create a new resonance at low frequency.…”

Beamforming MIMO Array Antenna for 5G-Millimeter-Wave Application

“…The mmw high gain antenna using RO 4003C and RO 5880 substrates resonated in 22.0 -32.0 GHz [28], and CP-SIW antenna on Rogers 4350B resonated in 27.1 -29.95 GHz (LHCP) and 26.55 -29.55 GHz (RHCP) have better 5G performance characteristics [29]. MIMO antenna with dual band elimination characteristics [30], with identical dual-antenna building blocks (DABBs) [31], and for X-band satellite communication [32] were designed for 5G communication system.…”

High‐isolation eight‐element MIMO array for unbroken metal‐rimmed smartphone applications

“…Usually, to ensure the performance of antennas, many slits were loaded on the metallic frame. [19][20][21][22][23][24][25][26][27][28] Open-slot antennas can integrate with metallic frames easily with good performances, which were widely adopted in the MIMO systems for metal-rimmed smartphones. [19][20][21][22] In Reference 27, the differential-fed network was used to obtain good isolation.…”