Performance enhancement of the compact defected ground structure Multi-port MIMO antenna with modified FSS structure for 5G NR mm wave applications

Abstract

A Compact millimeter-wave Multiple-Input Multiple-Output (MIMO) antenna is presented for next-generation 5G wireless communication. The antenna is designed on a Rogers RT/Duroid 5870 substrate having a thickness of 0.79 mm with a relative permittivity of about 2.33 and a low dielectric loss of nearly 0.0012 to obtain high efficiency at high frequencies. The presented design structure exhibits circular patch geometry having decoupling slots and stubs and Defected Ground Structure (DGS), to achieve a better operating bandwidth and higher inter-element decoupling properties. Furthermore, the inclusion of a two-layered Frequency Selective Surface (FSS) beneath the antenna enhances its gain significantly. The two-layered FSS array has been modified by removing the unit cells from the central area to enhance its performance. Additionally, the radii of circular unit cells in the upper and lower FSS layers are intentionally modified to target different frequency regions, so that enhanced gain can be made stable in the entire frequency range. The presented design also exhibits a very compact size of 13.4 mm x 13.4 mm × 8.89 mm that enables it to integrate into space-constrained systems. The antenna is characterized by a high efficiency in a broad frequency spectrum extending from 24 to 35 GHz, including mm-wave frequency bands. The maximum gain of the MIMO-FSS structure is 8 dB, and the inter-element decoupling is lower than -20 dB. The design also exhibits enhanced performance metrics of diversity, which ensures a high data rate. Experimental results closely match with simulation outcome, which confirms the validity and feasibility of the presented antenna in high-frequency wireless devices for the next generation.