A Novel Water-Substrate-Based Dual-UWB Conformal Antenna with Radiation Stability for Diverse IIoMT Applications

Abstract

This work presents a water-substrate-based conformal implantable antenna (WSCIA) designed for Industrial Internet of Medical Things (IIoMT) applications. The antenna exhibits ultra-wideband (UWB) characteristics across the Industrial, Scientific, and Medical bands at 915 MHz and 2400 MHz, enabling efficient wireless power transfer and high-data-rate biotelemetry. It achieves a bandwidth of 510 MHz (0.71–1.23 GHz) in the 915 MHz band and 1.30 GHz (1.80–3.10 GHz) in the 2400 MHz band. The antenna exhibits strong radiation stability in varying tissue environments, ensuring reliable performance under realistic implantation conditions. Measured peak realized gains are –24.87 dBi at 915 MHz and –22.03 dBi at 2400 MHz, with corresponding radiation efficiencies of 0.76% and 0.80%. The specific absorption rate (SAR) analysis using an anatomically realistic human model confirms compliance with safety guidelines. Link margin and received power analyses confirm reliable telemetric communication at distances beyond 10 m for 915 MHz and 5 m for 2400 MHz, supporting high data rates of up to 120 Mb/s. Owing to the dielectric similarity between water and human tissue, the proposed WSCIA enables efficient electromagnetic (EM) energy transfer and, through 3D printing, offers a lightweight and cost-effective alternative to traditional substrate-based antenna designs. Collectively, the dual-UWB performance, radiation stability, low SAR, compact design, and frequency tunability make the proposed WSCIA a promising solution for next-generation IIoMT-based implants. Furthermore, its structural flexibility and stable EM performance in diverse environments make it suitable for anatomically constrained regions, particularly the scalp, heart, and gastrointestinal tract, where reliable wireless communication and safe long-term implantation are critical