Fig. 2: Electromagnetic characterizations of the body area network (BAN).
From: A robust near-field body area network based on coaxially-shielded textile metamaterial
a Inter-unit cell coupling coefficient k as a function of the inter-unit cell overlap α. b Measured transmission coefficient S21 of BANs with different α and numbers of unit cells N. The NFC load modulation requires an NFC passband that can be used to leverage an optimal α value. c Measured transmission coefficient and the simulated magnetic field strength along a 12-unit inline array. d Simulated magnetic field \(\left|H\right|\) at 13.56 MHz along two arrays, showing robust signal transmission. The 12-unit inline array demonstrates spectral stability after machine washing, being drenched, or entirely immersed in DI water when configured straight (e), with multiple bends (f), and 720° winded (g). Insets: Pictures of the textile metamaterial array being deformed while powering three battery-free LED nodes. h The BAN is insensitive to loss induced by conductive matter, covering the NFC passband when submerged in saline solutions. Inset: Measured transmission coefficient at 13.56 MHz with increasing salt concentration.
