Compact wideband MIMO mobile‐antenna system design using mode‐based decoupling techniques

Abstract

This work focuses on designing small mobile antennas and their multiple‐input multiple‐output (MIMO) applications. In this study, it was investigated that small mobile antennas can obtain high radiation performance only when a tight coupling with the ground plane is generated through ground‐mode tuning (GMT) of the ground plane. Furthermore, a novel mode‐based decoupling concept is presented for their MIMO applications, based on a four‐port network and by considering the ground‐mode effect. Consequently, the proposed mode‐based decouplers can effectively sustain high radiation performance and improve the isolation while providing low correlation by generating diagonally directed radiation patterns. In the proposed MIMO system, both GMT structures and mode‐based decouplers are implemented utilizing the metal rims around the ground plane, thereby occupying very compact clearance, and the measured MIMO antennas fully covered 0.69 to 1 GHz band with high isolation up to 20 dB and low envelope correlation coefficient (ECC) value below 0.5, sufficiently applicable in mobile devices.

4-Port MIMO Antenna Using Common Radiator on a Flexible Substrate for Sub-1GHz, Sub-6GHz 5G NR, and Wi-Fi 6 Applications

“…The antenna also has a -10dB bandwidth from 0.69-1.01 GHz, 2.64-3.17 GHz, 5.3-6.08 GHz, and 6.73-6.95 GHz, in the simulated frequency range. In the sub-1GHz band, due to the proximity of the ports in comparison to the operating wavelength, the isolation deteriorates and I > 10dB among ports is a reasonable choice [21][22][23]. However, in the present case, it is 8.6dB between the two orthogonal ports.…”

“…Based on these criteria, a distinction between sub 1-GHz and above 1-GHz antennas can be inferred from [21]. Owing to the ground plane size with respect to the operating frequencies, for the sub-1GHz antennas, IBW= -6dB and I ≥10 dB have been used in [21][22]. Seldom, a multiport antenna to operate below 1.0 GHz has been designed [23].…”

Compact Sub-6 GHz Four-Element Flexible Antenna for 5G Applications

“…Many MIMO antenna designs with a variety of aspects can be found in the literature [4][5][6][7][8][9]. Two elements [10,11], four elements [5,[12][13][14], six elements [15], etc., can be utilized in MIMO antenna designs.…”

Ridge gap waveguide antenna array with improved mutual isolation for millimeter wave applications

“…Antenna engineers have been concerned about decreasing the interactions between antenna elements in antenna array because of the mutual coupling between these elements 1‐6 . Planar antennas that include patch and slot elements encounter mutual coupling issues because of the substrate used, as well as the need to have large‐scale antenna arrays.…”