Compact Solution for a Wearable Multi-Band Rectenna

In this paper we introduce a multi-source RF harvesting system designed by a combination of CAD tools integrating nonlinear techniques with electromagnetic (EM) characterization of the passive portion of the system. The approach is first applied to a triple-band slotted ring wearable rectenna, designed to harvest RF energy from GSM 900, GSM 1800 and WiFi sources available in the ambient. Particular attention is devoted to the engineered solution in order to be compatible with technology garments. The same choices are then adopted for a tetra-band rectenna on traditional substrates, covering the UMTS band too, whose topology is obtained by exploiting a Genetic Algorithm (GA) optimization tool. In all cases the concurrent use of harmonic-balance (HB) technique and EM simulation allows the RF stationary design of the systems. The further use of a time-domain tool to include the base-band design of a dynamic converter allows to dynamically keep the system at its optimum loading condition