A multi-resonant MIMO antenna with dual-layer L-shaped grounding on FR4 for LTE, Sub-6 GHz and Wi-Fi 6E/7 portable devices

Abstract A compact and low-cost multiple-input multiple-output (MIMO) antenna system is proposed to meet the demands of modern portable wireless communication devices. The antenna is manufactured on an FR4 substrate measuring 10 × 60 × 0.8 mm 3 and operates efficiently in the LTE, Sub-6 GHz, and Wi-Fi 6E/7 bands. In particular, the system achieves a high peak gain of 9.32 dBi and a maximum radiation efficiency of 84%, covering operational frequency bands of 920–1040, 1810–2450, 3480–3780, and 5370–9000 MHz. The antenna structure does not rely on any passive matching components, yet it demonstrates excellent impedance matching, wide bandwidth, and strong inter-element isolation. To ensure the stable generation of multiple resonances, L-shaped grounding elements are integrated on both the top and bottom surfaces of the substrate. These grounding structures not only support the formation of multi-resonant modes but also contribute significantly to the suppression of mutual coupling, thereby enhancing MIMO performance reliability. To validate practical usability, the antenna system is integrated into two common platforms: a laptop and a smartphone. Both simulation and experimental results confirm that the proposed system offers robust wireless performance while satisfying the requirements for human-exposure-compliant design, making it a promising solution for high-band portable applications.