Miniaturized Dual-Band MIMO Implantable Antenna for IoMT-Enabled WCE and Deep Tissue Applications

Abstract

Implantable devices play a vital role in IoT-based healthcare, creating the need for compact, multi-band antennas that support high data rates for biotelemetry. This study presents a miniaturized dual-band, dual-port MIMO implantable antenna designed for wireless capsule endoscopy (WCE) and deep tissue applications. The antenna is integrated within a capsule-type device and has compact dimensions of 11.5 × 6 × 0.6mm3. It operates in the Industrial, Scientific, and Medical (ISM) bands of 433.1–434.8 MHz and 902–928 MHz. The proposed antenna supports the transmission of high-quality images and video over a considerable distance. Miniaturization and high isolation are achieved using carefully designed meandered lines. This design avoids the use of shorting vias or ground-plane slots, which simplifies the structure and reduces back radiation. As a result, it eliminates the need for a complex decoupling network to enhance isolation. This antenna is the first reported MIMO implantable design to operate in the lower ISM bands while maintaining an ultra-compact size. Following a detailed simulation-based analysis, a prototype was fabricated. The measured results showed excellent agreement with simulations. The antenna provides impedance bandwidths of 61 MHz (466–405 MHz) and 112 MHz (846–958 MHz), and measured gains of –40.2 dBi and –35 dBi at 433 and 915 MHz, respectively. Specific absorption rate (SAR) analysis was conducted to ensure compliance with IEEE safety standards. A link margin study was also performed, demonstrating reliable communication for high data rates of 1, 78, and 120 Mbps, with a minimum coverage distance of 10 meters based on SAR constraints. To assess diversity performance, envelope correlation coefficient (ECC) and diversity gain (DG) were evaluated and found within acceptable limits. The antenna also exhibits pattern diversity at both operational bands. The proposed design offers a reliable and compact solution for high-data-rate, SAR-compliant biotelemetry in modern IoT-based healthcare systems.