A Metasurface-Based Low-Profile Array Decoupling Technology to Enhance Isolation in MIMO Antenna Systems

Abstract

In this paper, a metasurface-based coupling reduction method is presented with the advantage of low profile for the MIMO antenna array. Unlike other metasurface-based decoupling technologies, this proposed metasurface for decoupling is loaded in the same layer as the coupled two-element patch antennas. Hence, the profile of the proposed decoupled array is greatly reduced compared to that of other published metasurface-based decoupled arrays. In this design, the two patch antennas with a short edge-to-edge distance of approximately 0.06 λ are surrounded by the period split ring resonator (SRR) elements. Next, two prototypes are fabricated; the test results show that the isolation performance for the decoupled array is better than that of a coupled array without SRRs, and the value of |S21| improves from-8 dB to-25 dB in a wide band of 5.0-6.0 GHz with |S21|<-25 dB. The impedance matching bandwidths for two arrays without and with SRRs are approximately 700 MHz (12.7%) and 1500 MHz (27%), respectively, with |S11|<-10 dB. In other words, a high-isolation MIMO array with the advantages of a low profile and a compact size is realized. It is exciting that the peak gains for the proposed decoupled array are improved by approximately 2 dB in the entire working band range. In addition, the efficiencies of the decoupled array increase by 15% compared to those of the coupled array, and the envelope correlation coefficient (ECC) also greatly improves. Therefore, the signs suggest that this proposed metasurface-based decoupling method is an efficient measure for MIMO array applications in the future.

16-Port Non-Planar MIMO Antenna System With Near-Zero-Index (NZI) Metamaterial Decoupling Structure for 5G Applications

“…The ECC, TARC and CCL values are extracted by using relations provided in [34]- [37]. Equation 11is used to calculate the envelope correlation coefficient for antenna elements placed across and side-by-side configuration.…”

Closely‐coupled wideband MIMO antenna with isolation improvement using decoupling circuit and hexagonal split‐ring resonators

“…A group of these methods is hosted an arbitrary structure between the MIMO antenna elements. Such as slots and meandering line, 2 orthogonal feeding, 3 metamaterial absorber, 4 diversity techniques, 5 EBG structure, 6 bandstop filter, 7 and split ring resonator 8 . However, many works of the literature employ either antenna configuration properties to improve isolation, which requires a good understanding of the design structures.…”

“…Such as slots and meandering line, 2 orthogonal feeding, 3 metamaterial absorber, 4 diversity techniques, 5 EBG structure, 6 bandstop filter, 7 and split ring resonator. 8 However, many works of the literature employ either antenna configuration properties to improve isolation, which requires a good understanding of the design structures. Moreover, some of them using a specifically designed structure in between MIMO antenna to achieve isolation.…”

Split-Ring Resonator-Loaded Baffles for Decoupling of Dual-Polarized Base Station Array

“…However, it inevitably increased the profile of the array. The second type changed the coupling mode to orthogonal polarization [8], [9] or transformed the propagation coupling waves into evanescent waves by using a single negative permeability metasurface [10], [11]. However, these methods were not suitable for dual-polarized BS arrays.…”