Hexagonal Shaped 4-Port MIMO Filtering Antenna with High Gain & Low Mutual Coupling for Multiuser Applications

Abstract

This research presents an advanced 4-port multiple-input multiple-output (MIMO) antenna designed to address the rigorous requirements of 5G/6G, ultra-wideband (UWB), and Internet of Things (IoT) applications. The antenna features four hexagonal-shaped radiating elements interfaced with 50 Ω microstrip feed lines, arranged rotationally to achieve orthogonal polarization, effectively minimizing mutual coupling and enhancing MIMO diversity for superior system performance. Fabricated on a compact 60 x 60 mm² FR4 substrate, the design incorporates a filtenna architecture, integrating antenna and filter functionalities to eliminate switching components like PIN diodes, which often disrupt radiation patterns due to biasing circuits. A defected ground structure (DGS) further improves inter-element isolation and frequency selectivity, ensuring high performance within a minimal footprint. Designed and simulated using Ansys HFSS, the antenna was validated through fabrication and testing with an Agilent N5247A Vector Network Analyzer, with electromagnetic characterization conducted in an anechoic chamber across 1-20 GHz. It delivers a wideband impedance bandwidth of 6.7 GHz (17.50-24.20 GHz) with a return loss (S11) better than -20 dB, alongside inter-element isolation exceeding -20 dB. Performance metrics include a peak gain of 7 dBi, omnidirectional radiation patterns, low Total Active Reflection Coefficient (TARC), minimal Envelope Correlation Coefficient (ECC), high Diversity Gain (DG), and negligible Channel Capacity Loss (CCL). Time-domain analysis confirms its suitability for UWB applications, showcasing low distortion and robust signal fidelity. The antenna’s applications are profound for mm-Wave 5G/6G networks, enabling high-data-rate, low-latency communications in dense urban environments through MIMO’s channel hardening and favorable propagation properties. For UWB, it supports precision ranging and high-bandwidth IoT networks, such as smart cities and industrial automation. Its compact design is ideal for handheld devices, base stations, and embedded systems, addressing miniaturization challenges. The research’s significance lies in overcoming mutual coupling and spectral interference through innovative filtenna and DGS integration, enhancing spectral efficiency and scalability for next-generation networks. By providing a compact, high-performance solution validated through rigorous simulation and experimental protocols, this work sets a benchmark for MIMO antenna designs, driving advancements in massive MIMO and beyond-5G systems.