Contents I. Introduction
Wearable devices have witnessed a surge in popularity in recent years, becoming integral components of our daily lives. Smartwatches [1] [2], rings [3], eyeglasses [4], and other wearable technologies are designed to seamlessly integrate into various aspects of our routine, offering functionalities ranging from health monitoring to communication, entertainment, and more. One notable frontier in wearable technology is the Internet of Medical Things (IoMT), where these devices play a pivotal role in revolutionizing healthcare services. The IoMT facilitates the connection of medical devices and applications, enabling remote monitoring of many vital signs such as heart rate, blood pressure, real-time data collection, and improved patient care [5]. Among the innovations in IoMT, wrist worn antennas stand out as a noteworthy development due to their popularity, convenience, and ease of integration in with daily activities [6]. Nevertheless, designing an effective wristband antenna poses a host of challenges. One of the primary considerations is the integration of the antenna within the limited physical space available on a wristband. Furthermore, the mechanical properties of the antenna's substrate material play a crucial role in ensuring flexibility and conformability to the curved shape and the movement of the wrist, ensuring a comfortable fit for the user and optimal antenna performance. Flexible materials, including silicone, plastic, and polyimide, have been widely employed in designing wristband antennas for wearables [7] [8]. Opting for textile materials like leather offers various advantages, such as higher flexibility, conformability, and seamless integration into clothing and accessories, promoting discreet and fashionable antenna placement. Additionally, it is essential that the antenna exhibits a robust performance against the body loading together with a low SAR (Specific Absorption Rate) to secure the safety of the wearer [9]. The communication of smart devices in IoMT is possible through such frequency bands as Wi-Fi/ BT, ISM, and GPS. Most of the studied wristband antenna are single band antenna [10] [11]. Proposing an antenna, which is capable to operate simultaneously at multiple frequency bands is of significance and preferable over single band. Hence, in this work, we propose a flexible dual-band wristband antenna designed to operate properly across both 5G and Wi-Fi frequency bands. The paper is organized as follows: Section 2 details the antenna design methodology. Section 3 outlines the results and discussions regarding the proposed antenna's performance in free space and on the human hand, along with a comparative table referencing prior works. Finally, Section 4 provides the concluding remarks.
