Eight Element Side Edged Framed MIMO Antenna Array for Future 5G Smart Phones

Abstract

This paper presents a novel design of a Multiple Input Multiple Output (MIMO) antenna system for next generation sub 6 GHz 5G and beyond mobile terminals. The proposed system is composed of a main board and two side boards. To make the design cost-effective, FR4 is used as a substrate. The design is based on a unit monopole antenna etched at the side substrate. The single element is resonating at 3.5 GHz attaining a 10 dB bandwidth of 200 MHz and a 6 dB bandwidth of 400 MHz. The single element is then transformed into an MIMO array of 8-elements with an overall dimension of 150 mm × 75 mm × 7 mm, providing pattern diversity characteristics and isolation better than -12 dB for any two radiating elements. A number of studies such as effects of human hand on the system that includes single hand mode and dual mode scenarios and the effects of Liquid Crystal Display (LCD) over the principal performance parameters of the system are presented. The envelop correlation coefficient (ECC) is computed for all the scenarios and it is found that ECC is less than 0.1 for any case and maximum channel capacity is 38.5 bps/Hz within the band of interest. The main advantage of the proposed design over available designs in the literature is that almost all of the main substrate is empty providing wide space for different sensors, systems, and mobile technology components. A brief literature comparison of the proposed system is also presented. To validate the proposed model, a prototype is fabricated and results are presented. This design can be applied on higher frequencies to future micromachines for on chip communications using same theocratical approach as the space for higher frequencies in mmwave spectrum has been reserved. The simulated results are in an excellent agreement with the measured results. All the main performance parameters of the design are calculated and compared with the measured results wherever possible.

Keywords: 5G; Liquid Crystal Display (LCD); MIMO antenna; mobile terminals; smart city; smart phone.

Figure 1

(a): Perspective view of the proposed Multiple Input Multiple Output (MIMO) system, (b): single monopole antenna element.

Figure 2

Return loss of different antenna designs.

Figure 3

Effects of A6x on the reflection coefficient of a single element.

Figure 4

(a) Fabricated prototype front view, (b) far-field measurement set up.

Figure 5

(a): Reflection coefficient of proposed MIMO configuration, (b): port isolation of antenna element 1, (c): port isolation of selected antenna elements, (d): measured S-parameters of antenna elements 1 and 3, (e): measured S-parameters of antenna elements 5 and 7.

Figure 5

(a): Reflection coefficient of proposed MIMO configuration, (b): port isolation of antenna element 1, (c): port isolation of selected antenna elements, (d): measured S-parameters of antenna elements 1 and 3, (e): measured S-parameters of antenna elements 5 and 7.

Figure 6

Total efficiency and maximum gain over frequency of MIMO antenna system.

Figure 7

Simulated and measured radiation patterns for (a) antenna element (AE)-1, (b) AE-3, (c) AE-5, and (d) AE-7.

Figure 8

Envelope correlation coefficient (ECC) of the proposed MIMO antenna system.

Figure 9

Channel capacity of the proposed MIMO antenna system.

Figure 10

User hand influence of (a): single hand mode (SHM) and (b): two hand mode (THM).

Figure 11

Performance parameters in single hand mode (SHM): (a): S-parameters, (b): port isolation, (c): ECC.

Figure 12

Performance parameters in two hand mode (THM): (a): S-parameters, (b): port isolation, (c): ECC.

Figure 13

(a): Liquid crystal display (LCD) display module with the proposed MIMO antenna system, (b): parametric tuning of parameter A6x.