ABSTRACT
This chapter discusses the general description of RF-DC conversion circuits, particularly those designed for low input power levels. The general concepts and design techniques, as well as the most common circuit topologies, are presented. The RF-DC conversion efficiency of a rectenna is influenced not only by the amount of power loss in the diodes, by the impedance match between the antenna, the rectifier and between the rectifier and the load, but also by the antenna efficiency. The use of a single-Rectenna device for such a wireless energy transfer system would not be ideal because of the high uncertainty on the incident RF power level. Adifferent Rectenna structure was designed and optimized for each of the four regions, ensuring that it will have maximum RF-DC conversion efficiency within that region. The series-mounted diode rectenna is considered for very low input power level, while the bridge configuration addresses large input power range and the shunt-connected diode rectenna is suitable in the mid-range.
