Isolation enhancement in H-plane coupled 5G MIMO antenna with tight spacing using miniaturized epsilon negative (ENG) metamaterial

Abstract

A novel miniaturized epsilon negative metamaterial is proposed vide this article to address coupling in a tightly spaced H-plane configured two-element multiple input multiple output (MIMO) antenna operating at the globally popular 5G NR (new radio) band of 3.5 GHz frequency. Wave evanescence exhibited by the devised metamaterial unit element (MTM UE) (4.2 × 4.2 sq.mm) at 3.5 GHz resonance is verified by interposing the MTM UE array (5 × 1) in an MIMO antenna with an edge-to-edge spacing of 5 mm. Each radiator constituting the MIMO array (37 × 80.6 sq.mm) is a modified rectangular patch antenna with dimensions 27 × 33.4 sq.mm that are excited by the cost-effective microstrip transmission line. After the insertion of the proposed MTM unit element, the port isolation reported is <—20>9.8 dB) and Envelope Correlation Coefficient (<0.04) values from the radiation pattern, which adhered to the acceptance rate. Proposed MTM UE even rendered improved radiation gain with negligible impact on the efficiency. To verify the evanescence mechanism in real-time, the prototype covering the two-element MIMO with the proposed miniaturized MTM UE is fabricated and tested, which presents a perfect agreement. All these features make the proposed design viable for Wi-Max (IEEE 802.16e) (3.4–3.5 GHz) technology dedicated to space-constrained modern wireless applications. In addition, this article also presents the RLC equivalence derived for the proposed MTM UE and the two-element MIMO antenna.