Compact, Wearable Antennas for Battery-Less Systems Exploiting Fabrics and Magneto-Dielectric Materials

In this paper we describe some promising solutions to the modern need for wearable, energy-aware, miniaturized wireless systems whose typical envisaged application could be a Body Area Network (BAN). To reach this goal novel materials are adopted, such as fabrics, in place of standard substrates and metallizations, which require a systematic procedure for their electromagnetic characterization. Indeed the design of such sub-systems represents a big issue, since approximate approaches could result in strong deviations from the actual system performance. To face this problem, we demonstrate our design procedure, which is based on the concurrent use of electromagnetic software tools and nonlinear circuit-level techniques, able to simultaneously predict the actual system behavior of an antenna system, consisting of the radiating and of the nonlinear blocks, at the component level. This approach is demonstrated for the design of a fully wearable tri-band rectifying antenna (rectenna) and of a button-shaped electrically-small antenna deploying a novel magneto-dielectric substrate. Simulations are supported by measurements both in terms of antennas port parameters and far-field results.