Rim-Integrated Bluetooth Antenna for Smartwatches with Full-Metallic Structure

The integration of smart technology into wearable devices has been rapidly evolving, leading to the proliferation of smartwatches, fitness trackers, smart jewelry, and other connected accessories that blend functionality with everyday use. As these devices become increasingly compact, efficient, and sophisticated, the design of internal components, such as antennas, plays a critical role in optimizing performance. This paper explores the design, manufacturing, and prototype measurements of a Bluetooth antenna integrated into the metallic rim of a smartwatch. By embedding the antenna within the structural elements of the device, we address challenges related to space constraints, complicated metallic structure inside the smartwatch influencing the antenna pattern, and overall device aesthetics. The measured prototype showed a -10 dB impedance bandwidth over the 2.38-2.65 GHz frequency range, which encompasses 2.4-2.5 GHz range of interest, when measured on a human tissue phantom, with a total efficiency of 30%.