Multilayer, Multiband Compact Wearable Endfire Antenna for On-Body Communication

This paper investigates a compact, multilayered, multiband end-fire Yagi-Uda antenna through simulation in free space and on phantom. The antenna's design utilizes alternating layers of denim and latex substrates to achieve the desired end-fire radiation pattern. The proposed structure with phantom demonstrates three distinct end-fire radiations at resonant frequencies of 4.82 GHz, 5.22 GHz, and 5.65 GHz, with beam directions at angles of 22°, 40°, and 9°, and corresponding main beam directivities of 8.56 dBi, 9.25 dBi, and 3.60 dBi, respectively. To enhance beam performance near the human body and ensure compliance with Specific Absorption Rate (SAR) requirements, a 0.1 mm thick aluminum layer is added to the antenna's rear side. SAR analyses for 1 g and 10 g of tissue yielded values of 1.42 W/kg and 0.54 W/kg, respectively, meeting international safety standards.