Abstract—Multiple Input Multiple Output (MIMO) antenna is expected to form a major technique of 5G communication to get a high channel capacity. However the antenna performance is degraded significantly because of mutual coupling between close elements in portable equipments. In this paper, a novel EBG structure for 28/38GHz dual-band MIMO antenna with its equivalent is proposed. Having round shape and double side design, the proposed double-side EBG (DS-EBG) structure is able to improve significantly both mutual coupling and gain without any decoupling structure between antenna elements. Thus the MIMO antenna gets compact size of 15.3x8.5x0.79mm³ with no distance between antenna elements from edge to edge. The antenna radiation efficiency is also refined at both bands. This improvement has not attained from any previous EBG structure studies. At 28GHz, the radiation efficiency is increased from 83.2% to 87.6% while it is raised from 83.1% to 91.1% at 38GHz. Besides, the antenna achieves wide bandwidth of 7.1% and 13.16% at 28GHz and 38GHz, respectively that is suitable for 5G terminals. All dimensions of EBG cell as well as antenna are optimized by using Computer Simulation Technology (CST) software.
 

Index Terms—DS-EBG, 5G, millimeter wave antenna, mutual coupling

Cite: Duong Thi Thanh Tu, Nguyen Thi Bich Phuong, Pham Dinh Son, and Vu Van Yem, "Improving Characteristics of 28/38GHz MIMO Antenna for 5G Applications by Using Double-Side EBG Structure," Journal of Communications, vol. 14, no. 1, pp. 1-8, 2018. Doi: 10.12720/jcm.14.1.1-8