Wearable Dual-Layer Planar Magnetoinductive Waveguide for Wireless Body Area Networks

We have previously reported wearable magnetoinductive waveguides (MIWs) for wireless body area networks (WBANs) that significantly outperform the state-of-the-art in terms of path loss, data rate, interference, security, and more. MIWs placed in a planar way upon the human body are most promising but suffer from a large deterioration in performance under mechanical failures and clothing transitions (e.g., from 10.34 dB to 27.31 dB minimum loss and from 20% to 2.32% fractional bandwidth). In this work, we overcome both limitations via a novel dual-layer planar MIW design that uses two layers of resonant loops stacked upon each other. Concurrently, this design maintains all benefits of MIW-based WBANs and improves the link budget by >5 dB versus our previous single-layer MIWs and by >60-70 dB versus state-of-the-art WBANs. We herewith report a theoretical model of dual-layer MIWs that relies on the dispersion relation and validate it both numerically and experimentally. We also discuss the improvements versus our previously reported MIW designs and address design considerations, including electromagnetic safety. This work cements MIWs as a future technology to be used in low-loss WBANs for full-body applications.