Wireless Power Transfer (WPT) enables power to be transferred from a grid or storage unit to a device without the need for cable connections. This can be performed by inductive coupling of magnetic fields as well as by direct radiative transfer via beams of electromagnetic waves, commonly radiowaves, microwaves or lasers. Inductive coupling is the most widely used wireless technology with applications including charging handheld devices, RFID tags, chargers for implantable medical devices, and proposed systems for charging electric vehicles. Applications of radiative power transfer include solar power satellites and wireless powered drone aircraft. This book covers the very latest in theory and technology of both coupling and radiative wireless power transfer. Topics covered include the basic theory of inductive coupling and resonance coupling WPT; multi-hop WPT; circuit theory for wireless couplers; inverter/ rectifier technologies for WPT systems; basic theory of WPT via radio waves; technologies of antenna and phased array for WPT via radio waves; transmitter/rectifier technologies for WPT via radio waves; applications of coupling WPT for electric vehicle charging; applications of long-distance WPT; and biological interactions of electromagnetic fields and waves.