High isolation metamaterial based MIMO antenna with modified ground for 5G millimeter-wave applications

Abstract In this paper, a metamaterial-based Multiple-Input Multiple-Output (MIMO) antenna structure with high isolation at the N257 Band (from 26.5 to 29.5 GHz), of the 5G millimeter-wave applications is presented. A resonator structure based on a metamaterial (MTM) cell exhibiting low values of constitutive parameters and achieving a Near-Zero-Index (NZI) at the targeted frequency band is investigated by leveraging the Epsilon-Near-Zero (ENZ) principles. This MTM cell serves as the radiating element of our proposed antenna, placed at the end of a 50 microstrip feed line. A 50 dB isolation between a two elements antenna array is achieved through an isolation technique that combines the characteristics of the MTM cell with a modified ground plane. Furthermore, our antenna exhibits desirable performance metrics, including lower Envelope Correlation Coefficient (ECC < 0.0007) values, high diversity gain (DG > 9.99 dB) and lower Channel Capacity Loss (CCL < 0.4 bits/s/Hz), making it a promising candidate for 5G MIMO applications in the millimeter-wave range.