Field Decorrelation and Isolation Improvement in an MIMO Antenna Using an All-Dielectric Device Based on Transformation Electromagnetics

Usman Qureshi; Muhammad Umar Khan; Mohammad S Sharawi; Shah Nawaz Burokur; Raj Mittra

doi:10.3390/s21227577

Field Decorrelation and Isolation Improvement in an MIMO Antenna Using an All-Dielectric Device Based on Transformation Electromagnetics

Sensors (Basel). 2021 Nov 15;21(22):7577. doi: 10.3390/s21227577.

Authors

Usman Qureshi¹, Muhammad Umar Khan¹, Mohammad S Sharawi², Shah Nawaz Burokur³, Raj Mittra⁴

Affiliations

¹ Research Institute for Microwave and Millimeter-Wave Studies, National University of Sciences and Technology, Islamabad 44000, Pakistan.
² Department of Electrical Engineering, Polytechnique Montréal, Montréal, QC H3T 1J4, Canada.
³ LEME, UPL, Univ Paris Nanterre, F92410 Ville d'Avray, France.
⁴ Department of Electrical and Computer Engineering, University of Central Florida, Orlando, FL 32816, USA.

Abstract

This work presents a new technique for enhancing the performance of a multiple-input multiple-output (MIMO) antenna by improving its correlation coefficient ρ. A broadband dielectric structure is designed using the transformation electromagnetics (TE) concept to decorrelate the fields of closely placed radiating elements of an MIMO antenna, thereby decreasing ρ and mutual coupling. The desired properties of the broadband dielectric wave tilting structure (DWTS) are determined by using quasi-conformal transformation electromagnetics (QCTE). Next, the permittivity profile of the DWTS is realized by employing air-hole technology, which is based on the effective medium theory, and the DWTS is fabricated using the additive manufacturing (3D printing) technique. The effectiveness of the proposed technique is verified by designing two-element patch-based MIMO antenna prototypes operating at 3 GHz, 5 GHz, and 7 GHz, respectively. The proposed technique helped to reduce the correlation coefficient ρ in the range of 37% to 99% in the respective operating bandwidth of each MIMO antenna, thereby, in each case, improving the isolation between antenna elements by better than 3 dB, which is an excellent performance.

Keywords: 3D printing; additive manufacturing; correlation coefficient; multiple-input multiple-output (MIMO) antenna; transformation electromagnetics.