| Popis: |
Chapter 6 is dedicated to remote RF powering of autonomous sensors and in particular to RF energy harvesters. The RF energy transducer (antenna), matching networks, and ensuing rectifiers are presented. Based on circuits proposed in the literature, extensive simulations for several incoming power levels at the antenna (from −10 dBm to 10 dBm) were performed. We determine that circuit efficiency slightly depends on the number of stages used for the voltage rectifier multiplier, but varies widely with the received power (ranging, when using a shunt-inductor matching network, from 10% at −10 dBm to 80% at 10 dBm). Additionally, as the power level increases, so does the output voltage corresponding to maximum efficiency. For low power levels, LC matching networks provided higher efficiencies than shunt-inductor networks, at the cost of greater sensitivity to output voltage variations and to the value of the inductor. Experimental tests were performed with a folded dipole antenna (about 300 Ω), shunt inductor matching, a three-stage rectifier, and a storage unit composed of two series connected NiMH batteries. |
