Metamaterial Absorber-Integrated CP MIMO DRA for EMI Reduction and High Isolation

Abstract

This letter outlines a systematic approach for the design of a quad-port circularly polarized (CP) multiple-input–multiple-output (MIMO) ring dielectric resonator antenna (DRA) characterized by low mutual electromagnetic interference. A hexagonal stub placed in cross-ring shape, working as a metamaterial absorber, is employed to minimize coupling in a compact antenna system. A ring DRA, operating at 5.3 GHz, acts as a radiating element, excited by an unbalanced aperture and microstrip line. The unbalanced aperture, together with conformal arc strips loaded on the DRA, enables the circular polarization characteristics, generating left-hand CP (LHCP) radiation. The proposed absorber exhibits an absorption rate over 93%, with reflection approaching zero at the specified frequency. A $1\times 2$ array of vertical absorbers is incorporated in a vertical arrangement between the antenna elements to reduce the coupling. Material characterization and equivalent circuit model (ECM) analysis are performed to improve understanding of the fundamentals of operation. The antenna is fabricated and validated. The proposed MIMO antenna is a promising candidate for wirless local-area network and Wi-Fi networks.