Isolation Enhancement for MIMO Patch Antennas Using Near-Field Resonators as Coupling-Mode Transducers

An embeddable decoupling structure is proposed for massive multiple-input-multiple-output (M-MIMO) antennas in this paper. The embeddable decoupling structure is made up of an end-folded metal strip and a pair of C-shaped metal strips. By introducing the embeddable decoupling structure near two closely spaced dipole antennas, additional coupling can be generated to counterbalance the original mutual coupling between the dipole antennas. The decoupling structure is firstly designed for a 1×2 MIMO antenna, which can provide a reduction of about 5 dB for the mutual coupling. Then, an evolutional decoupling structure is designed, which is composed of a pair of inverted U-shaped metal strips and two parallel reversed C-shaped metal strips. The evolutional decoupling structure is employed in a 3×3 MIMO antenna operating in 5G bands to demonstrate its capability of decoupling. An average reduction of about 10 dB on mutual coupling is obtained over 3.3-4.5 GHz (30.8%). Moreover, it is found that the deteriorated radiation patterns due to the mutual coupling are improved. The decoupling structure can be totally embedded in a M-MIMO antenna, which has no increase in the antenna volume. The proposed decoupling structure exhibits advantages of radiation pattern distortion alleviation, wideband, embeddable, and dual-polarized capabilities for M-MIMO applications.

Section: Introductionmentioning

confidence: 99%

Embeddable Structure for Reducing Mutual Coupling in Massive MIMO Antennas

Qin

Cui

2020

“…Even the proposed neutralization line decoupling technology can be used for three-frequencies decoupled antennas [9] and UWB high isolation MIMO antennas [10]. In addition, near-field resonators (NFR) as a novel decoupling technique for closely packed patch elements in MIMO antennas is proposed [11]. The decoupling network (DN) [12,13] as an efficient approach for decoupling arrays.…”

Section: Introductionmentioning

confidence: 99%

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

Wang

et al. 2020

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.

“…After utilizing EBG to hinder the propagation of surface wave, the mutual coupling has been tremendously alleviated. Another decoupling concept of metastructure has been proposed in [15], the metasurface superstrate is utilized as a polarization converter for surface wave coupling mode. When surface wave coupling mode is orthogonal with antenna element resonant mode, the low correlation of antenna elements can be attained.…”

Section: Introductionmentioning

confidence: 99%

Enhancing MIMO Antenna Isolation Characteristic by Manipulating the Propagation of Surface Wave

Yang

Xiao

2020

Multiple-input multiple-output (MIMO) antennas have been a mainstream technology in fifth generation (5G) communications. However, strong mutual coupling between both adjacent and nonadjacent elements is inevitable, especially among highly integrated devices. In this paper, a slit embedded mushroom electromagnetic bandgap structure (EBG) is primarily proposed to suppress the propagation of surface wave between antenna elements. Subsequently, complementary split-ring resonators (CSRRs) are periodically arranged in two sides of the ground to steer the surface wave. By effectively utilizing the unusual electromagnetic property of EBG and CSRR to manipulate the propagation of surface wave, the mutual coupling between antenna elements has immensely alleviated. Finally, an H-shape defected ground structure (DGS) is introduced to reinforce decoupling effect. In order to validate the feasibility of the design principle, a prototype of the proposed antenna has been fabricated and measured. Measured results demonstrate that the decoupling concept in this paper is reasonable and approximately 12 dB reduction of mutual coupling is realized. INDEX TERMS Multiple-input multiple-output (MIMO), mutual coupling, slit embedded electromagnetic bandgap structure (EBG), complementary split-ring resonator (CSRR).