Mutual Coupling Reduction in MIMO DRA through Metamaterials

Muhammad Sabir Khan; Shahid Khan; Owais Khan; Sajid Aqeel; Neelam Gohar; Mariana Dalarsson

doi:10.3390/s23187720

Mutual Coupling Reduction in MIMO DRA through Metamaterials

Sensors (Basel). 2023 Sep 7;23(18):7720. doi: 10.3390/s23187720.

Authors

Muhammad Sabir Khan¹, Shahid Khan¹, Owais Khan¹, Sajid Aqeel¹, Neelam Gohar², Mariana Dalarsson³

Affiliations

¹ Department of Electrical and Computer Engineering, COMSATS University Islamabad, Abbottabad-Campus, Abbottabad 22060, Pakistan.
² Department of Computer Science, Shaheed Benazir Bhutto Women University, Peshawar 25000, Pakistan.
³ School of Electrical Engineering and Computer Science, KTH Royal Institute of Technology, SE 100-44 Stockholm, Sweden.

Abstract

A single negative metamaterial structure with hexagonal split-ring resonators (H-SRRs) is inserted within a two-port multiple-input multiple-output (MIMO) dielectric resonator antenna (DRA) in order to achieve a reduction of mutual coupling between closed multiple antenna elements. Between closed, tightly coupled, high-profile antenna elements, the single negative magnetic inclusions (H-SRRs) are embedded. By incorporating magnetic structures within antenna elements, the mutual coupling is significantly diminished. Mutual coupling reduction is attained by inserting an array of hexagonal split-ring resonators between the inter-spacing elements. An operative approach for the reduction of the mutual coupling between two × two MIMO DRAs initially operating at 5.2-GHz band is provided. To make the simulated design replica of the fabricated prototype, an air gap is introduced between the substrate, DRs, and H-SSRs. The addition of the air gap shifts the simulated results to 5.9 GHz, which closely resembles the measured values. The mutual coupling reduction is realized by integrating a meta-surface amid the two × two MIMO DRAs, which are settled in the H-plane. The meta-surface embraces an array of hexagonal split-ring resonator (H-SRR) cells that are unified along the E-plane. The H-SRR structure is designed to offer band-stop functionality within the antenna bandwidth. The proposed design has an overall dimension of 40 × 58.3 × 4.75 mm³ (1.5λ × 1.02λ × 0.079λ). By stacking the DRA with a one × three array of H-SRR unit cells, a 30 dB reduction in the mutual coupling level is attained without compromising on the antenna performance. The corresponding mutual impedance of the MIMO DRA is better than 30 dB over 5.9-6.1 GHz operating bandwidth. The proposed design has a DG of 10 db, ECC < 0.02, CCL < 0.02 bits/s/Hz, and an MEG of 0 dB. The overall design has a promising performance, which shows its suitability for the target wireless application.

Keywords: MIMO; dielectric resonator antenna; metamaterial; mutual coupling; split-ring resonator.

Grants and funding

This research received no external funding.