An Eight-Element Compact Low-Profile Planar MIMO Antenna Using LC Resonance with High Isolation

Abstract

(Print) 194 I. INTRODUCTIONIn multi-path environments, a high channel capacity is required in order to send more data in the desired direction. A multi-input multi-output (MIMO) antenna exploits multiple antenna elements to achieve a higher channel capacity that is proportionate to the number of antenna elements [1]. The conventional approach for MIMO applications is to arrange the antennas over more than half of the wavelength to avoid correlation [2]; thus, it extends the physical size of the antenna. Moreover, increasing the number of antenna elements in a mobile device affects MIMO performance due to mutual coupling between antennas.Several MIMO antenna designs have been proposed to minimize the mutual coupling between antenna elements and to simultaneously decrease the antenna size. The basic approach is to increase the space between antennas, but the space is limited, especially for mobile applications. Decoupling networks [3,4], the slit pattern [5], the parasitic element [6], and the electromagnetic band gap (EBG) [7,8] have been analyzed; however, these methods require additional space on an antenna. In this paper, we propose a compact low-profile planar MIMO antenna that unites eight inverted-F antennas with an isolationenhanced structure. We designed the proposed antenna to achieve high isolation between the antenna elements and we verified the antenna's function by identifying the surface current and radiation patterns. II. DESIGN OF THE PROPOSED ANTENNAThe antenna shown in Fig. 1 An eight-element compact low-profile multi-input multi-output (MIMO) antenna is proposed for wireless local area network (WLAN) mobile applications. The proposed antenna consists of eight inverted-F antennas with an isolation-enhanced structure. By inserting the isolation-enhanced structure between the antenna elements, the slot and capacitor pair generates additional resonant frequency and decreases mutual coupling between the antenna elements. The overall size of the proposed antenna is only 33 mm× 33 mm, which is integrated into an area of just 0.5 λ× 0. Manuscript received May 28, 2016 ; Revised July 6, 2016 ; Accepted July 6, 2016. (ID No. 20160528-017J) This is an Open-Access article distributed under the terms of the Creative Commons Attribution Non-Commercial License (http://creativecommons.org/licenses/ by-nc/3.0) which permits unrestricted non-commercial use, distribution, and reproduction in any medium, provided the original work is properly cited. ⓒ

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