# Compact Sub 6 GHz Slot Multiantenna System for 5G Laptops
## 1 Introduction
The system utilizes a modified E-slot on the ground, effectively reducing the coupling between the different antenna components by suppressing the ground current effect. The MIMO antenna structures in [10; 11] all adopt the open-slot design. Such design would require multiple openings in the exterior of a mobile device, which would detract from its esthetic appearance. Therefore, the ideal solution for mobile communication devices with metal back covers is to adopt a closed-slot structure without any openings. In [12], the authors proposed dual-band closely spaced closed-slot MIMO antennas for WiFi applications. The decoupling process involves simply etching slot lines based on the cancellation of the common and differential modes. In [13], the authors proposed a MIMO antenna structure that comes from the deployment of octagon-shaped resonant slots within the metallic ground plane. Due to the unique closed slot in the ground plane, wideband impedance was achieved. Although MIMO antenna structures with closed slots have been proposed in [12; 13], exciting high resonant modes that are not frequency-doubling of low resonant modes using long and straight slot structures will pose a challenge. To solve the limitations of the slotted and MIMO antennas, we designed a closed-slot dual-band 5G MIMO six-antenna design for laptops to be installed in 217 \(\times\) 3 mm\({}^{2}\) clearance space and at 1 mm from the top edge of the ground plane of screens. Its structure is simple. The width of its slot of only 3 mm. The first characteristic of this closed-slot antenna is that the high-frequency band (4800-5000 MHz) is not a multiplier of the low-frequency band (3300-3600 MHz). To support sub 6 GHz dual-band operations at 3300-3600 MHz and 4800-5000 MHz, an asymmetric T-shaped feed-in monopole with a 0.5 pF chip capacitor is used to excite the closed-slot antenna and trigger one-half and full wavelength resonance modes. The current distribution is varied due to a slight modification in the length of the central T-shaped stub [29]. The second characteristic of the proposed design is that the configuration distance between the two slots is only 5 mm, to form a six-antenna system in the same and parallel direction. By utilizing the weak electronic fields located at the two closed ends of the closed slot structure when it is excited, the antennas provide excellent envelope correlation coefficient (ECC) and isolation without the need for any decoupling elements. All the measured degrees of isolation were over 10 dB, and its efficiency was between 46% and 76%. The ECC values calculated from the measured complex electronic field radiation patterns were all below 0.2. The organization of the paper is as follows: Section 2 presents the MIMO antenna system design details. Then, the radiation performance of the antenna is discussed in Section 3, including reflection coefficients, transmission coefficients, ECC, efficiency, and radiation pattern. The ergodic channel capacity and its parametric study are described in Sections 4 and 5, respectively. Section 6 presents the MIMO antenna system characteristics' analysis, before the conclusion is presented in Section 7.