Miniaturized MIMO Antenna Array with High Isolation for 5G Metal-Frame Smartphone Application

Abstract

In this paper, a highly isolated multiple-input multiple-output (MIMO) antenna array is proposed for fifth-generation (5G) metal frame smartphones. The eight identical small-sized inverted F-shaped folded slots are etched on the metal frame as a MIMO antenna. The bandwidth of the antenna can be adjusted by changing one of the short branches of the antenna. The bandwidth of the antenna can reach the N79 band (4.4~5.0 GHz). By carefully arranging the positions of the eight antenna elements, ideal spatial diversity can be successfully achieved to mitigate the coupling between the antenna elements effectively. What is more, a small combination slot of C-shape (0.0078 × 0.047λ2) and vertical I-shape (0.12 × 0.004λ2) between each antenna element is introduced to improve the element isolation of the MIMO antenna system. The proposed MIMO array has been simulated, fabricated, and measured. The results show good impedance matching (return loss > 6 dB) and high isolation (>22 dB). Due to the decent element isolation, the envelope correlation coefficient (ECC) between each antenna element is below 0.049. It can provide a reliable anti-interference performance for the MIMO antenna system. In addition, the measured radiation efficiencies of the MIMO antenna system are higher than 50%. The interaction of the hand model with the MIMO antenna system is also investigated, including the specific absorption rate (SAR).

Design and Analysis of UWB MIMO Antenna for Smart Fabric Communications

“…It defnes how well a signal is transmitted with the minimum loss during transmission [33]. It can be calculated using the following equation [34]:…”

Compact Sub 6 GHz Slot Multiantenna System for 5G Laptops

“…As a result, the characteristics of many antennas installed in mobile communications devices are evolving into smaller sizes and lower profiles. Several multiple input, multiple output (MIMO) multiantenna systems for mobile devices and 5G applications [ 1 , 2 , 3 , 4 , 5 , 6 , 7 , 8 , 9 , 10 , 11 , 12 , 13 , 14 , 15 , 16 , 17 , 18 , 19 , 20 , 21 , 22 , 23 , 24 , 25 , 26 , 27 , 28 ] have been continuously proposed with the rapid spread of 5G MIMO technology, which also include the 5G MIMO multiantenna systems for mobile phones. In these systems, multiple antennas are configured at appropriate distances to maintain a certain degree of isolation.…”

“…In these systems, multiple antennas are configured at appropriate distances to maintain a certain degree of isolation. The spacing between the antennas in them is about 10–30 mm [ 2 , 3 , 4 , 5 , 6 , 7 , 8 , 9 , 10 , 11 , 12 , 13 ]. Some designs incorporate isolation elements to optimize the degree of isolation between antennas [ 14 , 15 ].…”

A Design for a Wide-Band Antenna Pair Applied for Mobile Terminals at the Sub-6 GHz Band

“…Previous research [18][19][20][21][22][23][24][25][26][27] presented MIMO antenna system designs applied to mobile terminals at sub-6G bands as shown in Table 1. In [18], an eight-port MIMO system was printed along the inner side of two sideboards.…”

“…A minimum antenna spacing of 21 mm was used, and a 12.6 × 3.5 mm 2 parasitic patch was placed between adjacent antenna elements, which achieved isolation below −14.5 dB. A MIMO system composed of eight slot antennas on the outside of the metal bezel was designed [19]. With the addition of I-shaped slots on the metal bezel and C-shaped DGS on the ground plane, isolation was achieved below −22 dB.…”