Investigation of a Compact and Flexible UWB Antenna With Low SAR for Wearable IoT Health Monitoring Applications

This research introduces a compact, flexible, and lightweight ultra‐wideband (CFL UWB) wearable antenna for IoT‐based health monitoring systems with low SAR, where the antenna serves as a key component. This design emphasizes broad bandwidth performance of 4.80–19.20 GHz, covering the 5.8‐GHz ISM band commonly used for Wi‐Fi, as well as the 10.40‐GHz band, which falls within the X‐band (8–12 GHz) used for high‐resolution microwave imaging, remote sensing, satellite communication, and high‐speed data links. The antenna features a rectangular patch with strategically introduced notches, a defective ground structure (DGS), L‐shaped slots at the ground plane edges, and a central vertical slot in the DGS to enhance impedance performance via optimized current distribution. Fabricated on a jeans substrate, it achieves a compact size of 17.5 × 15 × 1.7 mm 3 and an impedance bandwidth of 120%. The design delivers a peak simulated gain of 5.11 dBi at 20 GHz and maintains 99.9% radiation efficiency at 5.8 GHz under bending conditions. SAR values remain within safe limits, measured at 0.693 and 0.817 W/kg for 1‐g tissue, and 0.693 and 0.701 W/kg for 10 g tissue, respectively. These results demonstrate the compatibility of the antenna for efficient, safe, and high‐data‐rate wearable IoT‐based health monitoring applications.