Search

Recently, due to the fast development in multimedia applications of wireless communication systems and demands of increasing the capacity and data rates to meet the requirements of 5G mobile communication systems, new transmission techniques are needed. One of the powerful enabling tools of the 5G communication systems is the multi-input multi-output (MIMO) antenna system employing multiple antennas and utilizing the multipath fading mobile environment to increase the channel capacity without any additional bandwidth and/or transmitted power. However, because of the limited space of mobile devices, the distances between antennas are decreasing. The mutual coupling between antennas severely affects the overall performance of the MIMO system. So, isolation improvement methods are applied to reduce these influences. In this review, different isolation techniques and their features and drawbacks are presented, and the techniques for applying them in modern MIMO antenna systems are illustrated. Besides, the performance characteristics of these MIMO systems are compared. The review also contains basic concepts of the MIMO antenna system and its performance metrics. Finally, the future directions and trends for the MIMO antenna system design are discussed briefly. [ABSTRACT FROM AUTHOR]

This article introduces a dual-functional low-profile compact multiple input multiple output (MIMO) antenna array for multi-band communication in 5G smartphones. The proposed eight elements of the antenna array form two different 4×4 MIMO systems. The first four elements are placed at the four mobile corners and operate in a single band of 3.445-3.885 GHz for 5G n77 and n78 applications. The other system, in which four antennas are positioned in the middle of the terminal board, supports two wide bands of 1.684-2.300 GHz and 4.432-5.638 for n2, n3, n39, n65, n66, n79, and WLAN applications. The second iteration of a modified Peano-type fractal geometry served as the design foundation for the proposed antenna element. The system's ground plane design is based on self-isolated and spatial diversity methods. The single-band MIMO system's isolation is better than 23 dB. In the dual-band MIMO system that is based on self-isolation, isolation equals approximately 16 dB in the higher band and 10 dB in the lower band. To evaluate performance, radiation-related and total antenna efficiencies, scattering parameters and gains were investigated. Additionally, ECCs have been considered to evaluate MIMO performance. According to the results, such design constitutes a valuable option for MIMO applications in 5G smartphones. [ABSTRACT FROM AUTHOR]

A compact self-isolated Multi Input Multi Output (MIMO) antenna array is presented for 5G mobile phone devices. The proposed antenna system is operating at the 3.5 GHz band (3400-3600 MHz) and consists of eight antenna elements placed along two side edges of a mobile device, which meets the current trend requirements of full-screen smartphone devices. Each antenna element is divided into two parts, a front part and back part. The front part consists of an I-shaped feeding line and a modified Hilbert fractal monopole antenna, whereas the back part is an L-shaped element shorted to the system ground by a 0.5 mm short stub. A desirable compactness can be obtained by utilizing the Hilbert space-filling property where the antenna element's overall planar size printed on the side-edge frame is just (9.57 mm × 5.99 mm). The proposed MIMO antenna system has been simulated, analyzed, fabricated and tested. Based on the selfisolated property, good isolation (better than 15 dB) is attained without employing additional decoupling elements and/or isolation techniques, which increases system complexity and reduces the antenna efficiency. The scattering parameters, antenna efficiencies, antenna gains, and antenna radiation characteristics are investigated to assess the proposed antenna performance. For evaluating the proposed antenna array system performance, the Envelope Correlation Coefficients (ECCs), Mean Effective Gains (MEGs) and channel capacity are calculated. Desirable antenna and MIMO performances are evaluated to confirm the suitability of the proposed MIMO antenna system for 5G mobile terminals. [ABSTRACT FROM AUTHOR]