Wireless power transfer (WPT) is the transmission of electrical power from a power source to a consuming device without using discrete manmade conductors. Researchers have developed several techniques for moving electricity over long distance without wires.
Some exist only as theories or prototypes but others are already in use. This paper provides the techniques used for wireless power transmission. It is a generic term that refers to a number of different power transmission technologies that use time varying electromagnetic fields. Wirelesstransmission is useful to power electrical devices in case where interconnecting wires are inconvenient, hazardous, or are not possible.
For example the life of WSN is its node which consist of several device controllers, memory, sensors, actuators, transceivers and battery and battery. The transceiver can operate in four states, i.e 1) Transmit 2) Receive 3) Idle and 4) Sleep.
The major energy problem of a transmitter of a node is its receiving in idle state, as in this state it is always being ready to receive, consuming great amount of power. However, the batter has a very short lifetime and moreover in some developments owing to both practically and economically infeasible or may involve significant resists to human life. That is why energy harvesting for WSN in replacement of battery is the only and unique solution. In wireless power transfer, a transmitter device source, such as the mains power line, transmits power by electromagnetic fields across an intervening space to one or more receiver devices, where it is converted back to electric power and utilized.
In communication the goal is the transmission of information, so the amount of power reaching the receiver is unimportant as long as it is enough that signal to noise ratio is high enough that the information can be received intelligibly. In wireless communication technologies, generally, only tiny amounts of power reach the receiver. By contrast, in wireless power, the amount of power received is the important thing, so the efficiency (fraction of transmitted power that is received) is the more significant parameter. undefined undefined undefined undefined undefined undefinedundefined undefined undefined undefined undefined