Simulation and Analysis of a Reconfigurable Electrically Small Antenna System for Compact Wearable Devices

This work analyses a reconfigurable electrically small antenna (ESA) system operating in a limited design space at multiple 5G-NR bands (901–933 MHz and 1.635-2.1 GHz) in a switchable form under an area constraint of 63.2x25 mm 2 (0.19xO.07 λ 2). First, the area constraints and operating frequencies are analysed using the Chu-Harrington limit, followed by a study of the surface currents of the ESA and chassis using characteristic mode analysis. Then, a matching circuit is designed and integrated to enable both aperture tuning and input matching of the antenna. Simulations results indicated a single band operation at 901-923MHz (2.4BW%) in configuration 1, and a dual band operation at 914-933MHz (2BW%) and at 1.635-2.1 GHz (12.4 BW %) in configuration 2. Finally, specific absorption rate is of the ESA is studied, indicating levels of 0.2-0.4 W /kg (averaged over 1 g of tissue).