Over the last few years, the interests on wireless power transmission and ambient RF energy harvesting have increased exponentially. This new technology is being developed to eliminate the need for battery replacement or charging of the small micro-power wireless devices, allowing them to operate completely autonomously. This book, therefore, provides some up-to-date research results in several cutting-edge technologies for wireless power transmission, including diode modeling, efficient collection of low-input RF power, rectenna for ambient RF power harvesting, expansion of rectifier's operating input power range, and so forth. The book content should help shed some light on this new and promising technology, and should be especially useful to professionals in antennas and rectifiers, or anyone else who may be considering the application of this new technology in commercial products.