Broadband extremely close-spaced 5G MIMO antenna with mutual coupling reduction using metamaterial-inspired...

Area of Science:

• Electromagnetics
• Materials Science
• Antenna Engineering

Background:

• Mutual coupling in Multiple-Input Multiple-Output (MIMO) antenna systems is a significant challenge, especially with closely spaced elements.
• This coupling degrades antenna performance, limiting data throughput and overall system efficiency.
• Metamaterials offer unique electromagnetic properties that can be exploited for antenna performance enhancement.

Purpose of the Study:

• To propose and validate a metamaterial-inspired superstrate structure for reducing mutual coupling in a two-element MIMO antenna system.
• To investigate the decoupling mechanism and performance improvements offered by the metamaterial superstrate.
• To demonstrate the effectiveness of the proposed structure for 5G frequency bands.

Main Methods:

• Design and simulation of a metamaterial structure with positive and negative permeability.
• Integration of the metamaterial structure as a superstrate for a closely spaced MIMO antenna system.
• Verification through full-wave electromagnetic simulations and experimental measurements.

Main Results:

• The metamaterial superstrate achieved high isolation (S21 < -15 dB) over a wide 22.3% bandwidth (4.2-5.25 GHz), covering the 5G band.
• A maximum isolation of 29 dB was measured, representing a significant improvement of 23 dB compared to the uncoupled case.
• The superstrate also enhanced antenna gain by over 0.5 dB across the matching band, with a peak improvement of 3.2 dB.
• Excellent agreement was observed between simulated and measured results.

Conclusions:

• The proposed metamaterial superstrate is highly effective in mitigating mutual coupling for compact MIMO antenna systems.
• The structure enables high-performance MIMO operation in close proximity, suitable for 5G and future wireless communication systems.
• The validated design offers a practical solution for improving antenna isolation and gain simultaneously.