Design and Optimization of Metamaterial-Based Dual-Band 28/38 GHz 5G MIMO Antenna With Modified Ground for Isolation and Bandwidth Improvement

Abstract

This letter presents a high-isolation dual-band multiple-input multiple-output (MIMO) antenna based on the ground plane modification and optimized metamaterials (MMs) for 5G millimeter-wave applications. The antenna is a monopole providing a dual-band response at 5G 28/38 bands with a small physical size (4.8 × 2.9 × 0.762 mm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sup> , excluding the feeding line). The MIMO consists of two symmetric radiating elements arranged adjacently with the mutual coupling of −19 dB and −17 dB at 28 and 38 GHz, respectively. Reducing the ground length enhances the isolation to 34.6 dB at 28 GHz, whereas embedding the MMs diminishes the coupling to −47 dB at 38 GHz. The trust-region gradient-based search algorithm is employed to optimize the MM structure dimensions and to enhance the isolation at 38 GHz. The MMs also contribute to the enhancement of bandwidth from 1.6 GHz to 1.7 GHz at 28 GHz (27.1–28.8 GHz) and from 2.75 GHz to 3.7 GHz at 38 GHz (35.2–38.9 GHz). The proposed system is capable of covering both 28/38 bands with low profile structure, high isolation, low envelope correlation coefficient (ECC) ( <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$\lt 0.2 \cdot 10^{-4}$</tex-math></inline-formula> ), and high diversity gain (DG) (>9.99 dB). These properties demonstrate the system applicability for 5G millimeter-wave cellular communications.